Publications by authors named "Fredrik Tiberg"

43 Publications

Patient-Reported Outcomes of Treatment of Opioid Dependence With Weekly and Monthly Subcutaneous Depot vs Daily Sublingual Buprenorphine: A Randomized Clinical Trial.

JAMA Netw Open 2021 May 3;4(5):e219041. Epub 2021 May 3.

Camurus, Lund, Sweden.

Importance: Patient-reported outcomes in the treatment of opioid dependence may differ between subcutaneously administered depot buprenorphine and daily sublingual buprenorphine.

Objective: To compare patient satisfaction between depot buprenorphine and sublingual buprenorphine in adult outpatients with opioid dependence.

Design, Setting, And Participants: This open-label, randomized clinical trial was conducted among adult patients with opioid dependence at 6 outpatient clinical sites in Australia from October 2018 to September 2019. Data analysis was conducted from October 2019 to May 2020.

Interventions: Participants were randomized to receive treatment with weekly or monthly depot buprenorphine or daily sublingual buprenorphine over 24 weeks.

Main Outcomes And Measures: The primary end point was the difference in global treatment satisfaction, assessed by the Treatment Satisfaction Questionnaire for Medication (TSQM) version 1.4 (range, 0-100; higher score indicates greater satisfaction) at week 24. Secondary end points included other patient-reported outcomes, including quality of life, treatment burden, and health-related outcomes, as well as measures of opioid use, retention in treatment, and safety.

Results: A total of 119 participants (70 [58.8%] men; mean [SD] age, 44.4 [10.5] years) were enrolled, randomized to, and received either depot buprenorphine (60 participants [50.4%]) or sublingual buprenorphine (59 participants [49.6%]). From the initial sample of 120, a participant (0.8%) in the sublingual buprenorphine group withdrew consent and did not receive study treatment. All participants were receiving sublingual buprenorphine when enrolled. The mean TSQM global satisfaction score was significantly higher for the depot group compared with the sublingual group at week 24 (mean [SE] score, 82.5 [2.3] vs 74.3 [2.3]; difference, 8.2; 95% CI, 1.7 to 14.6; P = .01). Improved outcomes were also observed for several secondary end points after treatment with depot buprenorphine (eg, mean [SE] treatment burden assessed by the Treatment Burden Questionnaire global score, on which lower scores indicate lower burden: 13.2 [2.6] vs 28.6 [2.5]; difference, -15.4; 95% CI, -22.6 to -8.2; P < .001). Thirty-nine participants (65.0%) in the depot buprenorphine group experienced 117 adverse drug reactions, mainly injection site reactions of mild intensity following subcutaneous administration, and 12 participants (20.3%) in the sublingual buprenorphine group experienced 21 adverse drug reactions. No participants withdrew from the trial medication or the trial due to adverse events.

Conclusions And Relevance: In this study, participants receiving depot buprenorphine reported improved treatment satisfaction compared with those receiving sublingual buprenorphine. The results highlight the application of patient-reported outcomes as alternative end points to traditional markers of substance use in addiction treatment outcome studies.

Trial Registration: anzctr.org.au Identifier: ANZCTR12618001759280.
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http://dx.doi.org/10.1001/jamanetworkopen.2021.9041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111483PMC
May 2021

Optimal dose of buprenorphine in opioid use disorder treatment: a review of pharmacodynamic and efficacy data.

Drug Dev Ind Pharm 2020 Jan 8;46(1):1-7. Epub 2020 Jan 8.

Camurus AB, Lund, Sweden.

There is currently no consensus regarding optimal dose or dose-range of buprenorphine (BUP) for treatment of opioid use disorder (OUD). To elucidate the relationship between BUP dose and opioid receptor blockade, retention in treatment and illicit opioid drug use. Systematic review of the scientific literature through searches in the databases MEDLINE and PubMed. The review of the opioid receptor blockade studies did not find evidence that a daily sublingual (SL) BUP tablet dose higher than 16 mg confers added blockade benefit, while doses under 8 mg are insufficient to produce opioid receptor blockade. The data are inconclusive regarding the relative effectiveness of an 8 mg SL BUP tablet dose versus a 16 mg SL BUP tablet dose in terms of opioid receptor blockade. The review did not establish any clear relationship between BUP dose and treatment retention or illicit opioid use. The BUP dose in treatment of OUD should be individualized based on a continuous clinical benefit-risk assessment. Further research is needed to better understand the relationship between dose and efficacy over time in patients with this complex disorder.
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http://dx.doi.org/10.1080/03639045.2019.1706552DOI Listing
January 2020

Long-term safety of a weekly and monthly subcutaneous buprenorphine depot (CAM2038) in the treatment of adult out-patients with opioid use disorder.

Addiction 2019 08 3;114(8):1416-1426. Epub 2019 Jun 3.

Camurus AB, Lund, Sweden.

Aims: To assess the long-term safety of subcutaneous buprenorphine (CAM2038) weekly and monthly depots.

Design: Phase 3, open-label, observational, multi-centre 48-week trial (ClinicalTrials.gov NCT02672111).

Setting: Twenty-six out-patient sites (United States, United Kingdom, Hungary, Denmark, Sweden, Germany, Australia) between 14 December 2015 and 12 April 2017.

Participants: Two hundred and twenty-eight adults with opioid use disorder; 227 received CAM2038 (37 initiated onto CAM2038 and 190 converted from sublingual buprenorphine).

Interventions: CAM2038 weekly (8, 16, 24 or 32 mg) or monthly (64, 96, 128 or 160 mg) with flexible dosing and individualized titration utilizing multiple CAM2038 weekly and monthly doses.

Measurements: Safety variables, urine toxicology samples and self-reported illicit opioid use were collected at each visit. Participants were administered a patient satisfaction survey at months 6 and 12, completed by 162 of 227 (71.4%) participants.

Findings: The study treatment period was completed by 167 of 227 (73.6%) participants. At least one treatment-emergent adverse event (TEAE) was reported by 143 of 227 (63.0%) participants, of whom 60 of 227 (26.4%) reported as being drug-related. Most of the TEAEs, reported by 128 of 227 (56.4%) of participants, were mild or moderate in intensity. Injection-site reactions were reported by 46 of 227 (20.3%) participants, with most [45 of 46 (97.8%)] reported as mild to moderate. Five participants (2.2%) discontinued the study drug due to a TEAE, two cases (0.9%) of which were injection-site-related. No serious adverse events were attributed to the study drug. Among those remaining in the study, the percentage of opioid-negative urine tests combined with self-reports was 63.0% (17 of 27) in new-to-treatment participants and 82.8% (111 of 134) for those converted from sublingual buprenorphine. Participants reported high levels of satisfaction with CAM2038.

Conclusions: Subcutaneous buprenorphine delivered weekly or monthly (CAM2038) was well tolerated, with a systemic safety profile consistent with the known profile of sublingual buprenorphine. CAM2038 weekly and monthly was associated with high retention rates and low levels of illicit opioid use throughout this study.
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http://dx.doi.org/10.1111/add.14636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6771955PMC
August 2019

Octreotide SC depot in patients with acromegaly and functioning neuroendocrine tumors: a phase 2, multicenter study.

Cancer Chemother Pharmacol 2019 02 8;83(2):375-385. Epub 2018 Dec 8.

Endocrinology, DiMI and CEBR, University of Genoa, Genoa, Italy.

Purpose: Octreotide SC depot is a novel, ready-to-use formulation administered via a thin needle. In a phase 1 study in healthy volunteers, this formulation provided higher bioavailability of octreotide with faster onset and stronger suppression of IGF-1 in healthy volunteers versus long-acting intramuscular (IM) octreotide. This phase 2 study evaluated the pharmacokinetics, efficacy, and safety of octreotide SC depot in patients with acromegaly and functioning NETs, previously treated with octreotide IM.

Methods: Adult patients with acromegaly or functioning NETs treated for ≥ 2 months with octreotide IM [10/20/30 mg every 4 weeks (q4w)] received the last dose of octreotide IM treatment in study period 0 and were randomized 28 days later to receive octreotide SC depot 10 mg q2w, or 20 mg q4w for 3 months (period 1). The primary objective was to characterize the PK profile of octreotide SC depot after each injection vs PK for octreotide IM (period 0).

Results: Twelve patients were randomized to receive octreotide SC depot 10 mg q2w (acromegaly n = 3; NET n = 1) or 20 mg q4w (acromegaly n = 4; NET n = 4). Plasma levels of octreotide were higher with octreotide SC depot as compared to octreotide IM. Adverse events were reported in 6 and 8 patients during period 0 and period 1, respectively; most common in period 1 were gastrointestinal disorders.

Conclusion: Octreotide SC depot provided higher exposure (AUC) than octreotide IM, maintained biochemical control in patients with acromegaly and symptom control in patients with functioning NETs, and was well tolerated with a safety profile consistent with octreotide IM. CLINICALTRIALS.

Gov Identifier: NCT02299089.
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http://dx.doi.org/10.1007/s00280-018-3734-1DOI Listing
February 2019

Weekly and Monthly Subcutaneous Buprenorphine Depot Formulations vs Daily Sublingual Buprenorphine With Naloxone for Treatment of Opioid Use Disorder: A Randomized Clinical Trial.

JAMA Intern Med 2018 06;178(6):764-773

Braeburn Pharmaceuticals, Inc, Princeton, New Jersey.

Importance: Buprenorphine treatment for opioid use disorder may be improved by sustained-release formulations.

Objective: To determine whether treatment involving novel weekly and monthly subcutaneous (SC) buprenorphine depot formulations is noninferior to a daily sublingual (SL) combination of buprenorphine hydrochloride and naloxone hydrochloride in the treatment of opioid use disorder.

Design, Setting, And Participants: This outpatient, double-blind, double-dummy randomized clinical trial was conducted at 35 sites in the United States from December 29, 2015, through October 19, 2016. Participants were treatment-seeking adults with moderate-to-severe opioid use disorder.

Interventions: Randomization to daily SL placebo and weekly (first 12 weeks; phase 1) and monthly (last 12 weeks; phase 2) SC buprenorphine (SC-BPN group) or to daily SL buprenorphine with naloxone (24 weeks) with matched weekly and monthly SC placebo injections (SL-BPN/NX group).

Main Outcomes And Measures: Primary end points tested for noninferiority were response rate (10% margin) and the mean proportion of opioid-negative urine samples for 24 weeks (11% margin). Responder status was defined as having no evidence of illicit opioid use for at least 8 of 10 prespecified points during weeks 9 to 24, with 2 of these at week 12 and during month 6 (weeks 21-24). The mean proportion of samples with no evidence of illicit opioid use (weeks 4-24) evaluated by a cumulative distribution function (CDF) was an a priori secondary outcome with planned superiority testing if the response rate demonstrated noninferiority.

Results: A total of 428 participants (263 men [61.4%] and 165 women [38.6%]; mean [SD] age, 38.4 [11.0] years) were randomized to the SL-BPN/NX group (n = 215) or the SC-BPN group (n = 213). The response rates were 31 of 215 (14.4%) for the SL-BPN/NX group and 37 of 213 (17.4%) for the SC-BPN group, a 3.0% difference (95% CI, -4.0% to 9.9%; P < .001). The proportion of opioid-negative urine samples was 1099 of 3870 (28.4%) for the SL-BPN/NX group and 1347 of 3834 (35.1%) for the SC-BPN group, a 6.7% difference (95% CI, -0.1% to 13.6%; P < .001). The CDF for the SC-BPN group (26.7%) was statistically superior to the CDF for the SL-BPN/NX group (0; P = .004). Injection site adverse events (none severe) occurred in 48 participants (22.3%) in the SL-BPN/NX group and 40 (18.8%) in the SC-BPN group.

Conclusions And Relevance: Compared with SL buprenorphine, depot buprenorphine did not result in an inferior likelihood of being a responder or having urine test results negative for opioids and produced superior results on the CDF of no illicit opioid use. These data suggest that depot buprenorphine is efficacious and may have advantages.

Trial Registration: ClinicalTrials.gov Identifier: NCT02651584.
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http://dx.doi.org/10.1001/jamainternmed.2018.1052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145749PMC
June 2018

The lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and glycerol dioleate by phospholipase A and triacylglycerol lipase.

Chem Phys Lipids 2018 03 11;211:86-92. Epub 2017 Nov 11.

Physical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100, Lund, Sweden. Electronic address:

The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/glycerol dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A (PLA) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylglycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase.
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http://dx.doi.org/10.1016/j.chemphyslip.2017.11.011DOI Listing
March 2018

Effect of Buprenorphine Weekly Depot (CAM2038) and Hydromorphone Blockade in Individuals With Opioid Use Disorder: A Randomized Clinical Trial.

JAMA Psychiatry 2017 09;74(9):894-902

Braeburn Pharmaceuticals, Princeton, New Jersey.

Importance: Buprenorphine is an efficacious, widely used treatment for opioid use disorder (OUD). Daily oral transmucosal formulations can be associated with misuse, diversion, and nonadherence; these limitations may be obviated by a sustained release formulation.

Objective: To evaluate the ability of a novel, weekly, subcutaneous buprenorphine depot formulation, CAM2038, to block euphorigenic opioid effects and suppress opioid withdrawal in non-treatment-seeking individuals with OUD.

Design, Setting, And Participants: This multisite, double-blind, randomized within-patient study was conducted at 3 controlled inpatient research facilities. It involved 47 adults with DSM-V moderate-to-severe OUD. The study was conducted from October 12, 2015 (first patient enrolled), to April 21, 2016 (last patient visit).

Interventions: A total of five 3-day test sessions evaluated the response to hydromorphone (0, 6, and 18 mg intramuscular in random order; 1 dose/session/day). After the first 3-day session (ie, qualification phase), participants were randomized to either CAM2038 weekly at 24 mg (n = 22) or 32 mg (n = 25); the assigned CAM2038 dose was given twice, 1 week apart (day 0 and 7). Four sets of sessions were conducted after randomization (days 1-3, 4-6, 8-10, and 11-13).

Main Outcomes And Measures: The primary end point was maximum rating on the visual analog scale for drug liking. Secondary end points included other visual analog scale (eg, high and desire to use), opioid withdrawal scales, and physiological and pharmacokinetic outcomes.

Results: A total of 46 of 47 randomized participants (mean [SD] age, 35.5 [9] years; 76% male [n = 35]) completed the study. Both weekly CAM2038 doses produced immediate and sustained blockade of hydromorphone effects (liking maximum effect, CAM2038, 24 mg: effect size, 0.813; P < .001, and CAM2038, 32 mg: effect size, 0.753; P < .001) and suppression of withdrawal (Clinical Opiate Withdrawal Scale, CAM2038, 24 mg: effect size, 0.617; P < .001, and CAM2038, 32 mg: effect size, 0.751; P < .001). CAM2038 produces a rapid initial rise of buprenorphine in plasma with maximum concentration around 24 hours, with an apparent half-life of 4 to 5 days and approximately 50% accumulation of trough concentration from first to second dose (trough concentration = 0.822 and 1.23 ng/mL for weeks 1 and 2, respectively, with 24 mg; trough concentration = 0.993 and 1.47 ng/mL for weeks 1 and 2, respectively, with 32 mg).

Conclusions And Relevance: CAM2038 weekly, 24 and 32 mg, was safely tolerated and produced immediate and sustained opioid blockade and withdrawal suppression. The results support the use of this depot formulation for treatment initiation and stabilization of patients with OUD, with the further benefit of obviating the risk for misuse and diversion of daily buprenorphine while retaining its therapeutic benefits.

Trial Registration: Clinicaltrials.gov Identifier: NCT02611752.
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http://dx.doi.org/10.1001/jamapsychiatry.2017.1874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5710238PMC
September 2017

Pharmacokinetics and pharmacodynamics of a buprenorphine subcutaneous depot formulation (CAM2038) for once-weekly dosing in patients with opioid use disorder.

J Subst Abuse Treat 2017 07 14;78:22-29. Epub 2017 Apr 14.

Camurus AB, Ideon Science Park, Gamma Building, Sölvegatan 41, 223 70 Lund, Sweden. Electronic address:

Introduction: Sublingual buprenorphine is effective for opioid dependence treatment but associated with misuse, abuse, and diversion. The present Phase I/II study evaluated a novel buprenorphine subcutaneous depot formulation for once-weekly dosing (CAM2038 q1w) in patients receiving maintenance treatment for opioid use disorder with daily sublingual buprenorphine.

Methods: After discontinuation of buprenorphine for 48h, patients received a single CAM2038 q1w dose based on their pre-study daily sublingual maintenance dose. CAM2038 q1w doses of 7.5, 15, 22.5, and 30mg were administered in a sequential dose-escalating design. The following assessments were performed: pharmacokinetics of buprenorphine and norbuprenorphine, pharmacodynamics (evaluated using the Subjective and Clinical Opiate Withdrawal Scales), and time to intake of rescue sublingual buprenorphine medication.

Results: Single doses of CAM2038 q1w indicated dose-proportional buprenorphine pharmacokinetics (C and AUC), with time to C ~20h and an apparent terminal half-life of 3-5days, supporting once-weekly dosing. On average, patients showed a rapid and extended decrease in opiate-withdrawal symptoms from baseline, with zero or very low SOWS and COWS values measured at least up to 7days after dosing of CAM2038 q1w. The median time to first use of rescue buprenorphine was 10days. No dose dependence was seen in the pharmacodynamics, attributable to the selection of CAM2038 q1w doses based on patients' pre-study maintenance doses. CAM2038 q1w was safe and generally well tolerated.

Conclusions: Pharmacokinetics and pharmacodynamics of a novel buprenorphine subcutaneous depot formulation for once-weekly dosing was evaluated, suggesting utility in maintenance treatment of patients with opioid use disorder.
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http://dx.doi.org/10.1016/j.jsat.2017.04.008DOI Listing
July 2017

Pharmacokinetic Evaluation of Once-Weekly and Once-Monthly Buprenorphine Subcutaneous Injection Depots (CAM2038) Versus Intravenous and Sublingual Buprenorphine in Healthy Volunteers Under Naltrexone Blockade: An Open-Label Phase 1 Study.

Adv Ther 2017 02 9;34(2):560-575. Epub 2017 Jan 9.

Camurus AB, Ideon Science Park, 223 70, Lund, Sweden.

Introduction: CAM2038 q1w (once weekly) and q4w (once monthly) are investigational buprenorphine subcutaneous (SC) formulations based on FluidCrystal injection depot technology. These two drug products are being developed for opioid dependence treatment, with a target for once-weekly and once-monthly SC dosing. The rationale for developing two products with different dosing frequencies is that treatment strategies/routines, and hence different treatment preferences, can vary between patients, different stages of opioid maintenance treatment, and countries. This study evaluated the pharmacokinetics and safety of buprenorphine and norbuprenorphine following administration of CAM2038 q1w or q4w versus active controls.

Methods: Healthy volunteers were randomized to five treatment groups. All received a single intravenous dose of buprenorphine 600 µg, followed post-washout by a single dose of CAM2038 q4w 96 mg, a single dose of CAM2038 q4w 192 mg, or sublingual buprenorphine 8, 16, or 24 mg daily for 7 days, followed post-washout by a single dose of CAM2038 q4w 64 or 128 mg or four repeated weekly doses of CAM2038 q1w 16 mg. All subjects received daily naltrexone.

Results: Eighty-seven subjects were randomized. Median buprenorphine t after CAM2038 q4w was 4-10 h (24 h for CAM2038 q1w); mean terminal half-life was 19-25 days (5 days for CAM2038 q1w). CAM2038 q4w showed dose-proportional buprenorphine release, with similar exposure to repeat-dose CAM2038 q1w at comparable monthly dose level. Both CAM2038 formulations showed complete absolute bioavailability of buprenorphine and 5.7- to 7.7-fold greater buprenorphine bioavailability versus sublingual buprenorphine. CAM2038 q1w and q4w were well tolerated; subjects' acceptance was higher for CAM2038 than for sublingual buprenorphine 1 h post-dose.

Conclusions: The pharmacokinetic profiles of CAM2038 q1w and q4w versus sublingual buprenorphine support expected treatment efficacy with once-weekly and once-monthly dosing, respectively. CAM2038 formulations were safe and showed good local tolerability.

Trial Registration: ISRCTN24987553.

Funding: Camurus AB.
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http://dx.doi.org/10.1007/s12325-016-0472-9DOI Listing
February 2017

Interfacial properties of POPC/GDO liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces.

Phys Chem Chem Phys 2016 Sep;18(38):26630-26642

Physical Chemistry, Department of Chemistry, Lund University, P. O. Box 124, SE-221 Lund, Sweden.

Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and glycerol dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer.
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http://dx.doi.org/10.1039/c6cp04506eDOI Listing
September 2016

Octreotide s.c. depot provides sustained octreotide bioavailability and similar IGF-1 suppression to octreotide LAR in healthy volunteers.

Br J Clin Pharmacol 2015 Sep 6;80(3):460-72. Epub 2015 Aug 6.

Camurus AB, Lund.

Aims: The aim was to assess the pharmacokinetics, pharmacodynamics, safety and tolerability of octreotide subcutaneous (s.c.) depot, a novel octreotide formulation.

Methods: This was a phase I, randomized, open label study. After a single dose of octreotide immediate release (IR) 200 µg, subjects were randomized to one of eight groups to receive three monthly injections of octreotide s.c. depot A 10, 20 or 30 mg, B 30 mg, C 10, 20 or 30 mg or long acting octreotide (octreotide LAR) 30 mg.

Results: One hundred and twenty-two subjects were randomized. For all depot variants, onset of octreotide release was rapid and sustained for up to 4 weeks. The relative octreotide bioavailability of depot variants vs. octreotide IR ranged from 0.68 (90% confidence interval [CI] 0.61, 0.76) to 0.91 (90% CI 0.81, 1.02) and, vs. octreotide LAR, was approximately four- to five-fold greater: 3.97 (90% CI 3.35, 4.71) to 5.27 ng ml(-1) h (90% CI 4.43, 6.27). All depot variants showed relatively rapid initial reductions of insulin-like growth factor 1 (IGF-1) compared with octreotide LAR. A trend of octreotide dose dependence was also indicated from the plasma concentrations and suppression of IGF-1. Maximum inhibition of IGF-1 at steady-state was highest for depot B and C. All depot treatments were well tolerated. The most frequent adverse events were gastrointestinal related.

Conclusions: Octreotide s.c. depot provides greater octreotide bioavailability with a more rapid onset and stronger suppression of IGF-1 than octreotide LAR in healthy volunteers.
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http://dx.doi.org/10.1111/bcp.12698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4574831PMC
September 2015

Structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and glycerol dioleate.

Soft Matter 2015 Feb;11(6):1140-50

Physical Chemistry, Department of Chemistry, Lund University, P.O. Box 124, SE-22100, Lund, Sweden.

Well-defined, stable and highly structured I2 (Fd3̅m) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/glycerol dioleate (GDO), can be formed by using a low fraction (5-10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fd3̅m structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.
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http://dx.doi.org/10.1039/c4sm02296cDOI Listing
February 2015

Non-lamellar lipid liquid crystalline structures at interfaces.

Adv Colloid Interface Sci 2015 Aug 15;222:135-47. Epub 2014 Nov 15.

Physical Chemistry, Department of Chemistry, Lund University, POB 124, 221 00 Lund, Sweden; The Nanometer Structure Consortium (nmC@LU), Lund University, P.O. Box 118, SE-22100 Lund, Sweden. Electronic address:

The self-assembly of lipids leads to the formation of a rich variety of nano-structures, not only restricted to lipid bilayers, but also encompassing non-lamellar liquid crystalline structures, such as cubic, hexagonal, and sponge phases. These non-lamellar phases have been increasingly recognized as important for living systems, both in terms of providing compartmentalization and as regulators of biological activity. Consequently, they are of great interest for their potential as delivery systems in pharmaceutical, food and cosmetic applications. The compartmentalizing nature of these phases features mono- or bicontinuous networks of both hydrophilic and hydrophobic domains. To utilize these non-lamellar liquid crystalline structures in biomedical devices for analyses and drug delivery, it is crucial to understand how they interact with and respond to different types of interfaces. Such non-lamellar interfacial layers can be used to entrap functional biomolecules that respond to lipid curvature as well as the confinement. It is also important to understand the structural changes of deposited lipid in relation to the corresponding bulk dispersions. They can be controlled by changing the lipid composition or by introducing components that can alter the curvature or by deposition on nano-structured surface, e.g. vertical nano-wire arrays. Progress in the area of liquid crystalline lipid based nanoparticles opens up new possibilities for the preparation of well-defined surface films with well-defined nano-structures. This review will focus on recent progress in the formation of non-lamellar dispersions and their interfacial properties at the solid/liquid and biologically relevant interfaces.
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http://dx.doi.org/10.1016/j.cis.2014.11.003DOI Listing
August 2015

Formation of highly structured cubic micellar lipid nanoparticles of soy phosphatidylcholine and glycerol dioleate and their degradation by triacylglycerol lipase.

ACS Appl Mater Interfaces 2014 May 7;6(10):7063-9. Epub 2014 May 7.

Department of Physical Chemistry, Lund University , P.O. Box 124, SE-22100 Lund, Sweden.

Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/glycerol dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5-10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narrow size distribution and exhibit good long-term stability. In pharmaceutical applications, biodegradation pathways of the drug delivery vehicles and their components are important considerations. In the second part of the study we show how the structure of the particles evolves during exposure to a triacylglycerol lipase (TGL) under physiological-like temperature and pH. TGL catalyzes the lipolytic degradation of acylglycerides, such as GDO, to monoglycerides, glycerol, and free fatty acids. During the degradation, the interior phase of the particles is shown to undergo continuous phase transitions from the reversed I2 structure to structures of less negative curvature (2D hexagonal, bicontinuous cubic, and sponge), ultimately resulting in the formation of multilamellar vesicles.
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http://dx.doi.org/10.1021/am501489eDOI Listing
May 2014

Treatment of oral mucositis pain following radiation therapy for head-and-neck cancer using a bioadhesive barrier-forming lipid solution.

Support Care Cancer 2014 Jun 18;22(6):1557-62. Epub 2014 Jan 18.

Department of Radiotherapy, Medical University, Sofia, Bulgaria.

Purpose: CAM2028, a vehicle that forms a bioadhesive lipid barrier when applied to the oral mucosa, was developed as a carrier system for local delivery of benzydamine, an NSAID used for pain relief in oral mucositis. This trial compared the analgesic effect of CAM2028 plus benzydamine (CAM2028-benzydamine) with unmedicated CAM2028 (CAM2028-control) for the treatment of oral mucositis in patients with head-and-neck cancer.

Methods: Thirty-eight study participants were enrolled during their 3rd to 4th week of radiation therapy. Participants were required to have symptomatic oral mucositis (WHO Grade 2 or above) at screening and pain scores of at least 6 on an 11-point Likert scale at screening and on each day before treatment with study medication. After undergoing radiation, patients were administered a single dose of CAM2028-control or CAM2028-benzydamine 2 days apart, in a randomized crossover fashion. Pain was assessed over the following 8 h.

Results: With both treatments, patients experienced a mean 40 % decrease in pain intensity at 6 h (the primary study endpoint). Both treatments resulted in significant pain relief within 5 min of application that was evident during the entire 8-h assessment period. There was no difference in pain relief between the two interventions at any time point. Both treatments were safe and well tolerated.

Conclusions: CAM2028-benzydamine and CAM2028-control were both efficacious in reducing pain in patients with oral mucositis related to radiation therapy for head-and-neck cancer. Analgesic effects of both medications were immediate, clinically significant, and persistent for up to 8 h.
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http://dx.doi.org/10.1007/s00520-014-2117-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008777PMC
June 2014

Bioadhesive lipid compositions: self-assembly structures, functionality, and medical applications.

Mol Pharm 2014 Mar 27;11(3):895-903. Epub 2014 Jan 27.

Biomedical Science, Faculty of Health and Society, Malmö University , SE-20506 Malmö, Sweden.

Lipid-based liquid crystalline compositions of phospholipids and diglycerides have unique bioadhesive properties with several medical applications, as exemplified by a lipid-based medical device indicated for management and relief of intraoral pain. The present paper describes the relation between self-assembly properties of phosphatidyl choline (PC) and glycerol dioleate (GDO) mixtures in the presence of aqueous fluids and functional attributes of the system, including: film formation and bioadhesion, intraoral coverage, acceptance by patients, and potential as a drug delivery system. The phase behavior of PC/GDO was characterized using synchrotron small-angle X-ray scattering. Functional properties, including the presence of study formulations at intraoral surfaces, ease of attachment, taste, and degree of and intraoral pain, were assessed in a crossover clinical pilot study in head and neck cancer patients. An optimum in functional properties was indicated for formulations with a PC/GDO weight ratio of about 35/65, where the lipids form a reversed cubic liquid crystalline micellar phase structure (Fd3m space group) over the relevant temperature range (25-40 °C).
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http://dx.doi.org/10.1021/mp400552uDOI Listing
March 2014

Adsorption of lipid liquid crystalline nanoparticles: effects of particle composition, internal structure, and phase behavior.

Langmuir 2012 Jul 11;28(29):10688-96. Epub 2012 Jul 11.

Physical Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.

Controlling the interfacial behavior and properties of lipid liquid crystalline nanoparticles (LCNPs) at surfaces is essential for their application for preparing functional surface coatings as well as understanding some aspects of their properties as drug delivery vehicles. Here we have studied a LCNP system formed by mixing soy phosphatidylcholine (SPC), forming liquid crystalline lamellar structures in excess water, and glycerol dioleate (GDO), forming reversed structures, dispersed into nanoparticle with the surfactant polysorbate 80 (P80) as stabilizer. LCNP particle properties were controlled by using different ratios of the lipid building blocks as well as different concentrations of the surfactant P80. The LCNP size, internal structure, morphology, and charge were characterized by dynamic light scattering (DLS), synchrotron small-ange X-ray scattering (SAXS), cryo-transmission electron microscopy (cryo-TEM), and zeta potential measurements, respectively. With increasing SPC to GDO ratio in the interval from 35:65 to 60:40, the bulk lipid phase structure goes from reversed cubic micellar phase with Fd3m space group to reversed hexagonal phase. Adding P80 results in a successive shift toward more disorganized lamellar type of structures. This is also seen from cryo-TEM images for the LCNPs, where higher P80 ratios results in more extended lamellar layers surrounding the inner, more dense, lipid-rich particle core with nonlamellar structure. When put in contact with a solid silica surface, the LCNPs adsorb to form multilayer structures with a surface excess and thickness values that increase strongly with the content of P80 and decreases with increasing SPC:GDO ratio. This is reflected in both the adsorption rate and steady-state values, indicating that the driving force for adsorption is largely governed by attractive interactions between poly(ethylene oxide) (PEO) units of the P80 stabilizer and the silica surface. On cationic surface, i.e., silica modified with 3-aminopropltriethoxysilane (APTES), the slightly negatively charged LCNPs give rise to a very significant adsorption, which is relatively independent of LCNP composition. Finally, the dynamic thickness measurements indicate that direct adsorption of intact particles occurred on the cationic surface, while a slow buildup of the layer thickness with time is seen for the weakly interacting systems.
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http://dx.doi.org/10.1021/la301579gDOI Listing
July 2012

Adsorption of lipid liquid crystalline nanoparticles on cationic, hydrophilic, and hydrophobic surfaces.

ACS Appl Mater Interfaces 2012 May 3;4(5):2643-51. Epub 2012 May 3.

Department of Physical Chemistry, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.

Investigation of nonlamellar nanoparticles formed by dispersion of self-assembled lipid liquid crystalline phases is stimulated by their many potential applications in science and technology; resulting from their unique solubilizing, encapsulating, and space-dividing nature. Understanding the interfacial behavior of lipid liquid crystalline nanoparticles (LCNPs) at surfaces can facilitate the exploitation of such systems for a number of potentially interesting uses, including preparation of functional surface coatings and uses as carriers of biologically active substances. We have studied the adsorption of LCNP, based on phosphatidylcholine/glycerol dioleate and Polysorbate 80 as stabilizers, at different model surfaces by use of in situ ellipsometry. The technique allows time-resolved monitoring of the layer thickness and the amount adsorbed, thereby providing insights into the restructuring of the lipid nanoparticle upon adsorption. The effects of solvent condition, electrolyte concentration, particle size, and surface chemistry on adsorbed layer properties were investigated. Furthermore, the internal structures of the particles were investigated by cryo-transmission electron microscopy and small angle X-ray diffraction on the corresponding liquid crystalline phases in excess water. LCNPs are shown to form well-defined layers at the solid-liquid interface with a structure and coverage that are determined by the interplay between the self-assembly properties of the lipids and lipid surface interactions, respectively. At the hydrophobic surface, hydrophobic interaction results in a structural transition from the original LCNP morphology to a monolayer structure at the interface. In contrast, at cationic and hydrophilic surfaces, relaxation is a relatively slow process, resulting in much thicker adsorbed layers, with thickness and adsorption behavior that to a greater extent reflect the original bulk LCNP properties.
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http://dx.doi.org/10.1021/am300301bDOI Listing
May 2012

Properties and effects of a novel liquid crystal nanoparticle formulation of docetaxel in a prostate cancer mouse model.

Eur J Pharm Sci 2010 Oct 13;41(2):369-75. Epub 2010 Jul 13.

Camurus, Ideon Science Park, Sölvegatan 41, Lund, Sweden.

Treatment with docetaxel is the standard of care as first line chemotherapy in castration resistant prostate cancer. Due to serious side effects from the commercially available Taxotere formulation, we aimed to develop a safe and effective nanoparticle formulation of docetaxel. Liquid crystal nanoparticles (LCNPs), based on phosphatidyl choline, glycerol dioleate and polysorbate 80 dispersed in excess aqueous solution, were produced by simple procedures as carriers of docetaxel. Their effect on tumor growth in male SCID mice inoculated with PC-3 cells was compared to the effect of Taxotere and empty LCNP vehicle. Immunohistochemistry was performed to evaluate cell proliferation, angiogenesis and apoptosis in tumor tissue. Docetaxel and lipid excipients were dispersed into well-defined LCNP, stable during long-term storage. Mice subjected to LCNP/docetaxel formulation showed a better tumor regression than mice treated with Taxotere, with an indication of better tolerability. Immunohistochemical staining showed a decreased expression of Ki-67 in tumors from LCNP/docetaxel treated animals, especially in the cores of the tumors, suggesting better penetration/absorption compared to Taxotere. A new lipid-based nanoparticle formulation has been developed as carrier for docetaxel. Treatment effects in SCID mice indicate that this may be an interesting alternative to the current marketed formulation product.
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http://dx.doi.org/10.1016/j.ejps.2010.07.003DOI Listing
October 2010

Interactions of lipid-based liquid crystalline nanoparticles with model and cell membranes.

Int J Pharm 2010 May 7;391(1-2):284-91. Epub 2010 Mar 7.

Institute of Biochemistry, Mokslininku 12, LT-086 62 Vilnius, Lithuania.

Lipid-based liquid crystalline nanoparticles (LCNPs) are interesting candidates for drug delivery applications, for instance as solubilizing or encapsulating carriers for intravenous (i.v.) drugs. Here it is important that the carriers are safe and tolerable and do not have, e.g. hemolytic activity. In the present study we have studied LCNP particles of different compositions with respect to their mixing behavior and membrane destabilizing effects in model and cell membrane systems. Different types of non-lamellar LCNPs were studied including cubic phase nanoparticles (Cubosome) based on glycerol monooleate (GMO), hexagonal phase nanoparticles (Hexosome) based on diglycerol monooleate (DGMO) and glycerol dioleate (GDO), sponge phase nanoparticles based on DGMO/GDO/polysorbate 80 (P80) and non-lamellar nanoparticles based on soy phosphatidylcholine (SPC)/GDO. Importantly, the LCNPs based on the long-chain monoacyl lipid, GMO, were shown to display a very fast and complete lipid mixing with model membranes composed of multilamellar SPC liposomes as assessed by a fluorescence energy transfer (FRET) assay. The result correlated well with pronounced hemolytic properties observed when the GMO-based LCNPs were mixed with rat whole blood. In sharp contrast, LCNPs based on mixtures of the long-chain diacyl lipids, SPC and GDO, were found to be practically inert towards both hemolysis in rat whole blood as well as lipid mixing with SPC model membranes. The LCNP dispersions based on a mixture of long-chain monoacyl and diacyl lipids, DGMO/GDO, displayed an intermediate behavior compared to the GMO and SPC/GDO-based systems with respect to both hemolysis and lipid mixing. It is concluded that GMO-based LCNPs are unsuitable for parenteral drug delivery applications (e.g. i.v. administration) while the SPC/GDO-based LCNPs exhibit good properties with limited lipid mixing and hemolytic activity. The correlation between results from lipid mixing or FRET experiments and the in vitro hemolysis data indicates that FRET assays can be one useful screening tool for parenteral drug delivery systems. It is argued that the hemolytic potential is correlated with chemical activity of the monomers in the mixtures.
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http://dx.doi.org/10.1016/j.ijpharm.2010.03.016DOI Listing
May 2010

Interaction between lamellar (vesicles) and nonlamellar lipid liquid-crystalline nanoparticles as studied by time-resolved small-angle X-ray diffraction.

Langmuir 2009 Apr;25(7):3999-4008

Center for Chemistry and Chemical Engineering, Physical Chemistry 1, Lund University, P.O. Box 124, SE-22100 Lund, Sweden.

The kinetics of structure change when dispersions of two different types of lipid-based liquid-crystalline phases, one lamellar and one reversed, are mixed has been investigated using synchrotron small-angle X-ray diffraction and ellipsometry. The systems studied were (i) cubic-phase nanoparticles (CPNPs) based on glycerol monooleate (GMO) stabilized with a nonionic block copolymer, Pluronic F-127; (ii) CPNPs based on phytantriol (PtOH) stabilized with D-alpha-Tocopheryl polyethylene glycol 1000 succinate (Vitamin E TPGS); and (iii) hexagonal-phase nanoparticles (HPNPs) based on a lipid mixture of diglycerol monooleate/glycerol dioleate, stabilized by Pluronic F-127. Time-resolved small-angle X-ray diffraction was used to track structural changes within nonlamellar nanoparticles when they interact with uni- and multilamellar vesicles of dioleoylphosphatidylcholine and dipalmitoylphatidylcholine. The results are very dependent on the type of nanoparticles under investigation. For GMO-based CPNPs, a strong interaction is observed on mixing with vesicular dispersions that leads to large changes in unit size dimensions as well as a later transition from cubic to lamellar structure. These results are in good agreement with previous studies on the interaction of GMO-based CPNPs with planar bilayers using neutron reflectivity, where the diffraction peak shifted with time upon mixing. The structural changes are much less prominent for the PtOH-based CPNPs and the HPNPs upon mixing with phospholipid vesicles. These results are correlated with those from measurement studying interactions between the liquid-crystalline nanoparticles and supported phospholipid bilayers by ellipsometry. Also, here the GMO-based CPNPs show more pronounced and rapid adsorption and interaction with the supported bilayer surface than do the other types of nonlamellar nanoparticles. The interaction also depends on the bilayer properties, where significantly slower lipid mixing is observed for a bilayer in the gel state compared to a bilayer in the liquid-crystalline phase. This study is not only relevant for drug-delivery applications but also shows the potential of synchrotron small-angle X-ray diffraction in studying time-dependent structural changes as a consequence of the interaction between different lipid self-assembled aggregates in complex systems.
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http://dx.doi.org/10.1021/la802768qDOI Listing
April 2009

A combined in vitro and in vivo study on the interactions between somatostatin and lipid-based liquid crystalline drug carriers and bilayers.

Eur J Pharm Sci 2009 Mar 8;36(4-5):377-85. Epub 2008 Nov 8.

Camurus, Ideon Science Park, Sölvegatan 41, SE-223 70 Lund, Sweden.

Somatostatin (SST) is a peptide hormone active in the regulation of the endocrine system via different somatostatin receptors subtypes. It inhibits the release of multiple secondary peptide hormones, affecting neurotransmission and cell proliferation. SST has a high therapeutic potential in the treatment of disease, such as acromegali, acute pancreatitis and gastroenteropathic endocrine tumors. However, its practical use is hampered by a short in vivo half-life of only a few minutes in man. For this reason more long-lived SST analogues, including octreotide and lanreotide, have been developed. Here we have used native SST as a model compound for a different approach of extending plasma half-lives of in vivo labile biomolecules. Through association of the peptide hormone with lipid-based liquid crystalline nanoparticle (LCNP) carriers, the terminal half-life of SST injected intravenously in rats is shown to be significantly extended from less than 10min to more than 1h. The effect on the in vivo circulation behavior depends on the mode of peptide association to the lipid particles and related physicochemical properties are discussed on the basis of in vitro light scattering, z-potential and adsorption measurements. It is concluded that application of the LCNP delivery system represents an interesting alternative to chemical modifications of in vivo sensitive therapeutically interesting peptides.
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http://dx.doi.org/10.1016/j.ejps.2008.11.001DOI Listing
March 2009

Structure of lyotropic self-assembled lipid nonlamellar liquid crystals and their nanoparticles in mixtures of phosphatidyl choline and alpha-tocopherol (vitamin E).

Phys Chem Chem Phys 2008 Nov 29;10(43):6483-5. Epub 2008 Sep 29.

Institute of Biochemistry, Mokslininku 12, Vilnius, LT-08662, Lithuania.

The structural/phase behaviour of self-assembled lyotropic liquid crystals formed in mixtures of a phospholipid and alpha-tocopherol (vitamin E) is presented.
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http://dx.doi.org/10.1039/b811251gDOI Listing
November 2008

Distribution of reaction products in phospholipase A2 hydrolysis.

Biochim Biophys Acta 2007 May 10;1768(5):1036-49. Epub 2006 Nov 10.

Oxford University, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, UK.

We have monitored the composition of supported phospholipid bilayers during phospholipase A(2) hydrolysis using specular neutron reflection and ellipsometry. Porcine pancreatic PLA(2) shows a long lag phase of several hours during which the enzyme binds to the bilayer surface, but only 5+/-3% of the lipids react before the onset of rapid hydrolysis. The amount of PLA(2), which resides in a 21+/-1 A thick layer at the water-bilayer interface, as well as its depth of penetration into the membrane, increase during the lag phase, the length of which is also proportional to the enzyme concentration. Hydrolysis of a single-chain deuterium labelled d(31)-POPC reveals for the first time that there is a significant asymmetry in the distribution of the reaction products between the membrane and the aqueous environment. The lyso-lipid leaves the membrane while the number of PLA(2) molecules bound to the interface increases with increasing fatty acid content. These results constitute the first direct measurement of the membrane structure and composition, including the location and amount of the enzyme during hydrolysis. These are discussed in terms of a model of fatty-acid mediated activation of PLA(2).
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http://dx.doi.org/10.1016/j.bbamem.2006.10.020DOI Listing
May 2007

Liquid crystalline phases and their dispersions in aqueous mixtures of glycerol monooleate and glyceryl monooleyl ether.

Langmuir 2007 Jan;23(2):496-503

Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, Lund, Sweden.

The aqueous phase behavior of mixtures of 1-glycerol monooleate (GMO) and its ether analogue, 1-glyceryl monooleyl ether (GME) has been investigated by a combination of polarized microscopy, X-ray diffraction, and NMR techniques. Three phase diagrams of the ternary GMO/GME/water system have been constructed at 25, 40, and 55 degrees C. The results demonstrate that the increasing amount of GME favors the formation of the reversed phases, evidenced by the transformation of the lamellar and bicontinuous cubic liquid crystalline phases of the binary GMO/water system into reversed micellar or reversed hexagonal phases. For a particular liquid crystalline phase, increasing the GME content has no effect on the structural characteristics and hydration properties, thus suggesting ideal mixing with GMO. Investigations of dispersed nanoparticle samples using shear and a polymeric stabilizer, Pluronic F127, show the possibility of forming two different kinds of bicontinuous cubic phase nanoparticles by simply changing the GMO/GME ratio. Also NMR self-diffusion measurements confirm that the block copolymer, Pluronic F127, used to facilitate dispersion formation, is associated with nanoparticles and provides steric stabilization.
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http://dx.doi.org/10.1021/la062344uDOI Listing
January 2007

Boundary lubrication under water.

Nature 2006 Nov;444(7116):191-4

Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.

Boundary lubrication, in which the rubbing surfaces are coated with molecular monolayers, has been studied extensively for over half a century. Such monolayers generally consist of amphiphilic surfactants anchored by their polar headgroups; sliding occurs at the interface between the layers, greatly reducing friction and especially wear of the underlying substrates. This process, widespread in engineering applications, is also predicted to occur in biological lubrication via phospholipid films, though few systematic studies on friction between surfactant layers in aqueous environments have been carried out. Here we show that the frictional stress between two sliding surfaces bearing surfactant monolayers may decrease, when immersed in water, to as little as one per cent or less of its value in air (or oil). We attribute this to the shift of the slip plane from between the surfactant layers, to the surfactant/substrate interface. The low friction would then be due to the fluid hydration layers surrounding the polar head groups attached to the substrate. These results may have implications for future technological and biomedical applications.
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http://dx.doi.org/10.1038/nature05196DOI Listing
November 2006

Physicochemical and drug delivery aspects of lipid-based liquid crystalline nanoparticles: a case study of intravenously administered propofol.

J Nanosci Nanotechnol 2006 Sep-Oct;6(9-10):3017-24

Physical Chemistry 1, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.

Liquid crystalline nanoparticles (LCNP) formed through lipid self-assembly have a range of attractive properties as in vivo drug delivery carriers. In particular they offer: a wide solubilization spectrum, and consequently high drug payloads; effective encapsulation; stabilization and protection of sensitive drug substances. Here we present basic physicochemical features of non-lamellar LCNP systems with a focus on intravenous drug applications. This is exemplified by the formulation properties and in vivo behavior using the drug substance propofol; a well-known anesthetic agent currently used in clinical practice in the form of a stable emulsion. In order to appraise the drug delivery features of the LCNP system the current study was carried out with a marketed propofol emulsion product as reference. In this comparison the propofol-LCNP formulation shows several useful features including: higher drug-loading capacity, lower fat-load, excellent stability, modified pharmacokinetics, and an indication of increased effect duration.
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http://dx.doi.org/10.1166/jnn.2006.402DOI Listing
December 2006

Interfacial behavior of cubic liquid crystalline nanoparticles at hydrophilic and hydrophobic surfaces.

Langmuir 2006 Oct;22(22):9169-74

Physical Chemistry 1, Center for Chemistry and Chemical Engineering, University of Lund, P.O. Box 124, SE-22100 Lund, and Camurus AB, Ideon Science Park, SE-22370 Lund, Sweden.

The adsorption behavior of self-assembled lipid liquid crystalline nanoparticles at different model surfaces was investigated in situ by use of ellipsometry. The technique allows time-resolved monitoring of the adsorbed amount and layer thickness under transient and steady-state conditions. The system under study was cubic-phase nanoparticle (CPNP) dispersions of glycerol monooleate stabilized by a nonionic block copolymer, Pluronic F-127. Depending on the surface properties and presence of electrolytes, different adsorption scenarios were discerned: At hydrophilic silica thick surface layers of CPNPs are generated by particle adsorption from dispersions containing added electrolyte, but no adsorption is observed in pure water. Adsorption at the hydrophobic surface involves extensive structural relaxation and formation, which is not electrolyte sensitive, of a classic monolayer structure. The different observations are rationalized in terms of differences in interactions among the CPNP aggregates, their unimer constituents, and the surface and show a strong influence of interfacial interactions on structure formation. Surface self-assembly structures with properties similar to those of the corresponding bulk aggregates appear exclusively in the weak interaction limit. This observation is in agreement with observations for surfactant self-assembly systems, and our findings indicate that this behavior is applicable also to complex self-assembly structures such as the CPNP structures discussed herein.
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http://dx.doi.org/10.1021/la061224jDOI Listing
October 2006

"Sponge" nanoparticle dispersions in aqueous mixtures of diglycerol monooleate, glycerol dioleate, and polysorbate 80.

Langmuir 2006 Jul;22(14):6328-34

Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.

Lipid nanoparticles of nonlamellar lyotropic phases have a wide solubilizing and encapsulating spectrum for a range of substances thanks to their nanostructured interior featuring both lipophilic and hydrophilic domains. As a consequence, these systems have emerged as promising drug delivery systems in various pharmaceutical and diagnostic applications. Here we present the phase behavior and dispersion properties of a novel three-component lipid system composed of diglycerol monooleate (DGMO), glycerol dioleate (GDO), and polysorbate 80 (P80) which shows several advantageous features relating to drug delivery applications including: spontaneous dispersion formation with a narrow size distribution and tunable particle phase-structure. The obtained phase diagram shows the presence of lamellar (L(alpha)), hexagonal (H(2)), and reverse bicontinuous cubic (V(2)) liquid crystalline phases and an inverse micellar (L(2)) solution. A particularly interesting observation is the presence of a phase region where two liquid phases coexist, most likely the L(2) and L(3) ("sponge phase"). These two phase structures appear also to coexist in the submicron particles formed in the dilute water region, where the L(3) element appears to stabilize nanoparticles with inner L(2) structure. Increasing the fraction of the dispersing P80 component results in the growth of the more water rich L(3) "surface phase" at the expense of the size of the inner L(2) core.
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http://dx.doi.org/10.1021/la060295fDOI Listing
July 2006

Self-assembled lipid superstructures: beyond vesicles and liposomes.

Nano Lett 2005 Aug;5(8):1615-9

Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P. O. Box 124, SE-221 00 Lund, Sweden.

A unique set of nanoparticle dispersions of self-assembled lipid mesophases with distinctive reversed cubic, hexagonal, and sponge phase structures has been prepared by use of original lipid combinations and a simple, generally applicable and scalable method. All key properties, particle size distributions, shape, phase structure, and stability, are controlled predictably and reproducibly. The results suggest the cross-disciplinary use of nonlamellar particle structures in science and technology as, for instance, biomimetics, in vivo drug delivery vehicles for diagnostic and therapeutic agents, protein crystallization matrices, and soft nanoporous materials.
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http://dx.doi.org/10.1021/nl050678iDOI Listing
August 2005