Publications by authors named "Leena Laitinen"

17 Publications

  • Page 1 of 1

Quantitative Prediction of CYP3A4 Induction: Impact of Measured, Free, and Intracellular Perpetrator Concentrations from Human Hepatocyte Induction Studies on Drug-Drug Interaction Predictions.

Drug Metab Dispos 2017 06 23;45(6):692-705. Epub 2017 Mar 23.

Drug Metabolism and Pharmacokinetics, Vertex Pharmaceuticals Inc., Boston, Massachusetts

Typically, concentration-response curves are based upon nominal inducer concentrations for in-vitro-to-in-vivo extrapolation of CYP3A4 induction. The limitation of this practice is that it assumes the hepatocyte culture model is a static system. We assessed whether correcting for: 1) changes in perpetrator concentration in the induction medium during the incubation period, 2) perpetrator binding to proteins in the induction medium, and 3) nonspecific binding of perpetrator can improve the accuracy of CYP3A4 induction predictions. Of the seven compounds used in this evaluation, significant parent loss and nonspecific binding were observed for rifampicin (29.3-38.3%), pioglitazone (64.3-78.6%), and rosiglitazone (57.1-75.5%). As a result, the free measured EC values (EC) of pioglitazone, rosiglitazone, and rifampicin were significantly lower than the nominal EC values. In general, the accuracy of the induction predictions, using multiple static models, improved when corrections were made for measured medium concentrations, medium protein binding, and nonspecific binding of the perpetrator, as evidenced by 18-29% reductions in the root mean square error. The relative induction score model performed better than the basic static and mechanistic static models, resulting in lower prediction error and no false-positive or false-negative predictions. However, even when the EC value was used, the induction prediction for bosentan, which is a substrate of organic anion transporter proteins, was overpredicted by approximately 2-fold. Accounting for the ratio of unbound intracellular concentrations to unbound medium concentrations (K) (0.5-7.5) and the predicted multiple-dose K (0.6) for bosentan resulted in induction predictions within 35% of the observed interaction.
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http://dx.doi.org/10.1124/dmd.117.075481DOI Listing
June 2017

VX-509 (Decernotinib)-Mediated CYP3A Time-Dependent Inhibition: An Aldehyde Oxidase Metabolite as a Perpetrator of Drug-Drug Interactions.

Drug Metab Dispos 2016 08 13;44(8):1286-95. Epub 2016 Jun 13.

Drug Metabolism and Pharmacokinetics (C.Z., L.L., S.L., H.T., A.C., N.H.) and Department of Chemistry (F.M.), Vertex Pharmaceuticals Inc., Boston, Massachusetts

(R)-2-((2-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyrimidin-4-yl)amino)-2-methyl-N-(2,2,2-trifluoroethyl)butanamide (VX-509, decernotinib) is an oral Janus kinase 3 inhibitor that has been studied in patients with rheumatoid arthritis. Patients with rheumatoid arthritis often receive multiple medications, such as statins and steroids, to manage the signs and symptoms of comorbidities, which increases the chances of drug-drug interactions (DDIs). Mechanism-based inhibition is a subset of time-dependent inhibition (TDI) and occurs when a molecule forms a reactive metabolite which irreversibly binds and inactivates drug-metabolizing enzymes, potentially increasing the systemic load to toxic concentrations. Traditionally, perpetrating compounds are screened using human liver microsomes (HLMs); however, this system may be inadequate when the precipitant is activated by a non-cytochrome P450 (P450)-mediated pathway. Even though studies assessing competitive inhibition and TDI using HLM suggested a low risk for CYP3A4-mediated DDI in the clinic, VX-509 increased the area under the curve of midazolam, atorvastatin, and methyl-prednisolone by approximately 12.0-, 2.7-, and 4.3-fold, respectively. Metabolite identification studies using human liver cytosol indicated that VX-509 is converted to an oxidative metabolite, which is the perpetrator of the DDIs observed in the clinic. As opposed to HLM, hepatocytes contain the full complement of drug-metabolizing enzymes and transporters and can be used to assess TDI arising from non-P450-mediated metabolic pathways. In the current study, we highlight the role of aldehyde oxidase in the formation of the hydroxyl-metabolite of VX-509, which is involved in clinically significant TDI-based DDIs and represents an additional example in which a system-dependent prediction of TDI would be evident.
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http://dx.doi.org/10.1124/dmd.116.071100DOI Listing
August 2016

[Heterotopic pregnancy during the second trimester is a severe complication of pregnancy].

Duodecim 2016 ;132(8):730-3

Heterotopic pregnancy is a rare form of ectopic pregnancy in which one gestational sac is found in the uterus and another one in an extrauterine location. The spontaneous heterotopic pregnancy of our patient continued until the second trimester. In the 19th week of pregnancy, undiagnosed ectopic pregnancy in the left fallopian tube ruptured into the abdominal cavity, leading to a massive intra-abdominal hemorrhage. Left-side uterine appendages were excised in open surgery, but intrauterine pregnancy continued in vital form. Histologic examination revealed the excised tumor to be an ectopic pregnancy. The hypotension experienced by the patient led, however, to severe brain damage of the intrauterine fetus and induced abortion.
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June 2016

Prolonged low-molecular-weight heparin use during pregnancy and subsequent bone mineral density.

Thromb Res 2016 Jul 19;143:122-6. Epub 2016 May 19.

University of Turku and Turku University Central Hospital, Kiinamyllynkatu 4-8, 20520 Turku, Finland. Electronic address:

Introduction: In contrast to unfractionated heparin (UFH), use of low-molecular weight heparin (LMWH) during pregnancy has not been reported to be associated with a significant decrease in bone mineral density (BMD). The aim of this study was to investigate whether long-term use of LMWH during pregnancy is associated with subsequent decrease in BMD or with increased number of osteoporotic fractures.

Materials And Methods: In this observational cohort study BMD was measured by dual energy X-ray absorptiometry (DEXA) 4-7years after the last delivery in 152 women. Ninety-two women had prolonged LMWH-exposure during pregnancy - 75 as prophylaxis and 17 as treatment for venous thromboembolic event (VTE). Dalteparin and enoxaparin were the LMWH-preparations used. Sixty women without LMWH-exposure served as controls. A questionnaire about lifestyle factors and medical history was filled out by the subjects.

Results: Lumbar spine BMD in the LMWH users was lower than that in the controls both in the prophylactic group (1.22g/cm(2) vs. 1.27g/cm(2); p=0.03), and in the treatment group (1.20g/cm(2) vs. 1.27g/cm(2); p=0.07). BMD in femoral neck did not differ between the LMWH-users and controls. However, after adjusting for potential confounding factors, LMWH-exposure did not remain associated with decreased BMD in lumbar spine. Use of contraceptive pills was positively associated with BMD in lumbar spine. Incidence of osteopenia was 13% in the LMWH-group and 8% in the control-group, (p=0.4). No osteoporosis or osteoporotic fractures were found.

Conclusions: Prolonged use of LMWH during pregnancy was not associated with subsequent decrease in BMD, osteopenia, osteoporosis, or osteoporotic fractures.
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http://dx.doi.org/10.1016/j.thromres.2016.05.016DOI Listing
July 2016

Discovery of VX-509 (Decernotinib): A Potent and Selective Janus Kinase 3 Inhibitor for the Treatment of Autoimmune Diseases.

J Med Chem 2015 Sep 10;58(18):7195-216. Epub 2015 Sep 10.

Vertex Pharmaceuticals Inc. , 50 Northern Avenue, Boston, Massachusetts 02210, United States.

While several therapeutic options exist, the need for more effective, safe, and convenient treatment for a variety of autoimmune diseases persists. Targeting the Janus tyrosine kinases (JAKs), which play essential roles in cell signaling responses and can contribute to aberrant immune function associated with disease, has emerged as a novel and attractive approach for the development of new autoimmune disease therapies. We screened our compound library against JAK3, a key signaling kinase in immune cells, and identified multiple scaffolds showing good inhibitory activity for this kinase. A particular scaffold of interest, the 1H-pyrrolo[2,3-b]pyridine series (7-azaindoles), was selected for further optimization in part on the basis of binding affinity (Ki) as well as on the basis of cellular potency. Optimization of this chemical series led to the identification of VX-509 (decernotinib), a novel, potent, and selective JAK3 inhibitor, which demonstrates good efficacy in vivo in the rat host versus graft model (HvG). On the basis of these findings, it appears that VX-509 offers potential for the treatment of a variety of autoimmune diseases.
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http://dx.doi.org/10.1021/acs.jmedchem.5b00301DOI Listing
September 2015

In vitro and in vivo isotope effects with hepatitis C protease inhibitors: enhanced plasma exposure of deuterated telaprevir versus telaprevir in rats.

J Med Chem 2009 Dec;52(24):7993-8001

Vertex Pharmaceuticals Incorporated, Cambridge, Massachusetts 02139, USA.

Telaprevir 2 (VX-950), an inhibitor of the hepatitis C virus (HCV(a)) NS3-4A protease, is in phase 3 clinical trials. One of the major metabolites of 2 is its P1-(R)-diastereoisomer, 3 (VRT-394), containing an inversion at the chiral center next to the alpha-ketoamide on exchange of a proton with solvent. Compound 3 is approximately 30-fold less active against HCV protease. In an attempt to suppress the epimerization of 2 without losing activity against the HCV protease, the proton at that chiral site was replaced with deuterium (d). The compound 1 (d-telaprevir) is as efficacious as 2 in in vitro inhibition of protease activity and viral replication (replicon) assays. The kinetics of in vitro stability of 1 and 2 in buffered pH solutions and plasma samples, including human plasma, suggest that 1 is significantly more stable than 2. Oral administration (10 mg/kg) in rats resulted in a approximately 13% increase of AUC for 1.
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http://dx.doi.org/10.1021/jm901023fDOI Listing
December 2009

Effect of cell differentiation and passage number on the expression of efflux proteins in wild type and vinblastine-induced Caco-2 cell lines.

Eur J Pharm Biopharm 2007 Sep 28;67(2):548-54. Epub 2007 Mar 28.

Division of Pharmaceutical Technology, University of Helsinki, Helsinki, Finland.

The mRNA level expression of MDR1, MRP1-6, BCRP and CYP3A4 was determined by quantitative PCR in wild type (Caco-2WT) and vinblastine-treated (Caco-2VBL) Caco-2 cells at different passage levels (32-53). Differentiation increased the mRNA levels of MDR1, BCRP and all the MRPs except MRP4. Corresponding mRNA levels were observed in Caco-2WT and Caco-2VBL, except that the expression of MRD1 was higher in Caco-2VBL than in Caco-2WT cells. CYP3A4 was barely detected in either cell line. MDR1 functionality was studied using rhodamine123 and verapamil as a substrate-inhibitor pair. Corresponding to the observed differences in mRNA levels, MDR1 activity was higher in the Caco-2VBL cells. In Caco-2WT, MDR1 functionality was elevated at low passage numbers (32-35) compared to higher ones (49-53). Verapamil inhibited MDR1 efflux except at higher passage Caco-2WT cells, where no MDR1 activity could be observed. The results support the use of Caco-2VBL cells in MDR1 screening. The functional expression is higher than in Caco-2WT and remains consistent across the studied passages without major differences in mRNA levels of other efflux proteins. As both the passage number and the level of cell differentiation affect the expression profile of efflux proteins, short-term cell growth protocols should be evaluated accordingly.
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http://dx.doi.org/10.1016/j.ejpb.2007.03.017DOI Listing
September 2007

Enhanced in vitro permeation of furosemide loaded into thermally carbonized mesoporous silicon (TCPSi) microparticles.

Eur J Pharm Biopharm 2007 Jun 1;66(3):348-56. Epub 2006 Dec 1.

Drug Discovery and Development Technology Center, University of Helsinki, Finland.

The combined release and permeation behavior of furosemide loaded into thermally carbonized mesoporous silicon (TCPSi) microparticles was studied in order to evaluate the potential of TCPSi-loading to improve permeation of furosemide, a BCS class IV compound. Permeation was studied across Caco-2 monolayers at pH 5.5, 6.8 and 7.4 from drug solutions and TCPSi particles. TCPSi-loaded furosemide (39% w/w) exhibited improved dissolution from the microparticles with greatly diminished pH dependence. At pH 5.5, where furosemide solubility restricted the amount that could be dissolved in the control solution to less than 30% of the dose contained in the TCPSi particles, the flux of TCPSi-loaded furosemide across Caco-2 monolayers was over fivefold compared to pre-dissolved furosemide. The improved permeation could be confirmed also from dose-corrected (% dose-permeated) results. At pH 6.8 and pH 7.4, where corresponding doses could be used in control solutions, more than fourfold permeability values were obtained with TCPSi-loaded furosemide. Effects on transepithelial electrical resistance (TEER) and mannitol permeability were monitored and suggest that monolayer integrity was not compromised by the drug-loaded TCPSi microparticles. The improved permeation observed from furosemide-loaded TCPSi particles suggests that the high local concentrations provided by the enhanced dissolution properties of TCPSi-loaded furosemide could prove beneficial for absorption.
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http://dx.doi.org/10.1016/j.ejpb.2006.11.021DOI Listing
June 2007

In-vitro mutagenic potential and effect on permeability of co-administered drugs across Caco-2 cell monolayers of Rubus idaeus and its fortified fractions.

J Pharm Pharmacol 2006 Nov;58(11):1545-52

Drug Discovery and Development Technology Center, Faculty of Pharmacy, University of Helsinki, Finland.

This study investigated the mutagenic, anti-mutagenic and cytotoxic effects of acetone extract of raspberry, Rubus idaeus L. (v. Ottawa) Rosaceae, and the isolated and characterized ellagitannin and anthocyanin fractions thereof, suitable for food applications. The studied raspberry extract and fractions did not show any mutagenic effects determined in the miniaturized Ames test and were not cytotoxic to Caco-2 cells at the used concentrations. However, the anti-mutagenic properties were changed (i.e. decreased mutagenicity of 2-nitrofluorene in strain TA98, and slightly increased mutagenicity of 2-aminoanthracene in strain TA100) with metabolic activation. Further, their influence on the permeability of co-administered common drugs (ketoprofen, paracetamol, metoprolol and verapamil) across Caco-2 monolayers was evaluated. The apical-to-basolateral permeability of highly permeable verapamil was mostly affected (decreased) during co-administration of the raspberry extract or the ellagitannin fraction. Ketoprofen permeability was decreased by the ellagitannin fraction. Consumption of food rich in phytochemicals, as demonstrated here with chemically characterized raspberry extract and fractions, with well-absorbing drugs would seem to affect the permeability of some of these drugs depending on the components. Thus their effects on the absorption of drugs in-vivo cannot be excluded.
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http://dx.doi.org/10.1211/jpp.58.11.0016DOI Listing
November 2006

Anthranoid laxatives influence the absorption of poorly permeable drugs in human intestinal cell culture model (Caco-2).

Eur J Pharm Biopharm 2007 Apr 28;66(1):135-45. Epub 2006 Sep 28.

Drug Discovery and Development Technology Center (DDTC), Faculty of Pharmacy, University of Helsinki, Finland.

Interactions between widely used anthranoid laxatives and other simultaneously administered drugs are not known. In this paper, the influence of rhein, danthron, sennidins A/B, sennosides A/B, and senna leaf infusion was investigated on the permeability of furosemide, ketoprofen, paracetamol, propranolol, verapamil, digoxin, and Rhodamine 123 across Caco-2 monolayers. The effects on monolayer integrity ([(14)C]mannitol permeability, TEER) were also determined. The in vitro absorption of highly permeable drugs was not strongly affected during co-administration of the laxatives. Furosemide permeability was enhanced by rhein and danthron (3.6 and 3.0-fold), which may partly be due to opening of the paracellular spaces and/or effects on active efflux. However, the secretory permeability of digoxin and Rho 123 was not strongly affected by rhein and danthron, suggesting that inhibition of MDR1 was not responsible for the increased permeation of furosemide. The absorptive permeability of digoxin was decreased by rhein and danthron, offering evidence for effects on apical membranes. The effects on monolayer integrity were detectable, but reversible. According to presented experiments, daily use of laxatives with well-absorbing drugs would seem unlikely to affect drug permeability, but the effects on the absorption of poorly permeable drugs cannot be excluded.
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http://dx.doi.org/10.1016/j.ejpb.2006.09.006DOI Listing
April 2007

Evaluation of cocktail approach to standardise Caco-2 permeability experiments.

Eur J Pharm Biopharm 2006 Nov 30;64(3):379-87. Epub 2006 Jun 30.

Drug Discovery and Development Technology Center (DDTC), Faculty of Pharmacy, University of Helsinki, Finland.

The purpose of this study was to investigate the suitability and reliability of n-in-one approach using FDA suggested compounds for standardising Caco-2 permeability experiments. Special attention was paid to the evaluation of rank order correlation and mechanistic insights of compound permeability. Transport studies with antipyrine, metoprolol, ketoprofen, verapamil, hydrochlorothiazide, ranitidine, mannitol and fluorescein were performed in 12- and 24-well formats, as single compounds and in cocktails under iso-pH 7.4 and pH-gradient (pH 5.5 vs. 7.4) conditions. Compounds were quantified using n-in-one LC/MS/MS analysis. The cocktail-dosing proved to be a feasible method to determine the permeability of the Caco-2 cell line and to introduce external standards for permeability tests. Even though sink conditions were lost in cocktail experiments for highly permeable compounds, the rank order of compound permeability and the classification to low and high permeability compounds remained unchanged between single and cocktail studies and permeability values of 12- and 24-well formats were directly comparable. Under pH-gradient conditions the margin between high and low permeability compounds was narrower due to the lower permeability (higher fraction of ionisation) of basic molecules. Of the compounds studied, antipyrine, metoprolol, hydrochlorothiazide and mannitol are suitable for evaluation and standardisation purposes of passive permeability, while fluorescein would function as paracellular marker under iso-pH 7.4. As efflux activity may vary between cell batches, verapamil is a useful marker for P-glycoprotein.
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http://dx.doi.org/10.1016/j.ejpb.2006.06.006DOI Listing
November 2006

Preclinical evaluation of rapeseed, raspberry, and pine bark phenolics for health related effects.

J Agric Food Chem 2005 Jul;53(15):5922-31

Department of Applied Chemistry and Microbiology, Division of Food Chemistry, University of Helsinki, P.O. Box 27 (Latokartanonkaari 11), 00014 University of Helsinki, Finland.

Rapeseed, raspberry, and pine bark are promising bioactive sources of plant phenolics selected from among ca. 100 previously screened plant materials for in vitro preclinical evaluation of health related effects. Phenolic extracts and isolated fractions of the selected materials were investigated for antioxidant, antimicrobial, antiinflammatory, and antimutagenic properties as well as for cell permeability. It was shown that rapeseed and pine bark phenolics and raspberry anthocyanins were good or excellent antioxidants toward oxidation of phosphatidylcholine membrane (liposomes), rapeseed oil (crude) phenolics were effective radical scavengers (DPPH test), and both raspberry and pine bark phenolics inhibited LDL oxidation. Rapeseed oil phenolics, principally vinylsyringol, raspberry anthocyanins, and pinoresinol and matairesinol, the principal components of pine bark phenolic isolate, were effective against formation of the proinflammatory mediator, prostaglandin E(2). Raspberry ellagitannins inhibited the growth of Proteus mirabilis and Klebsiella oxytoca. Pine bark and rapeseed had minor effects on the permeability of model drugs in Caco-2 experiments. None of the tested extracts were mutagenic nor toxic to Caco-2 cells or macrophages. Thus, phenolic isolates from rapeseed, raspberry, and pine bark and are safe and bioactive for possible food applications including functional foods intended for health benefit.
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http://dx.doi.org/10.1021/jf050554rDOI Listing
July 2005

Effects of extracts of commonly consumed food supplements and food fractions on the permeability of drugs across Caco-2 cell monolayers.

Pharm Res 2004 Oct;21(10):1904-16

Viikki Drug Discovery Technology Center (DDTC), Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland.

Purpose: Extracts made from berries, herbs, and various plant materials, which might possess a range of activities, are used as health promoting products. Because little is known about their effects on the absorption of co-administered drugs, the effects of some food supplements, Finnish berries, and herbs were studied on the permeability of some commonly used drugs.

Methods: The permeabilities of verapamil, metoprolol, ketoprofen, paracetamol, and furosemide were studied across Caco-2 cell monolayers with contemporaneously administered extracts from flax seed, purple loosestrife, and Scots pine bark; bilberries, cowberries, and raspberries; oregano, rosemary, and sage. Toxicological tests were conducted to determine cellular damage.

Results: The effects of extracts on drug permeabilities were generally minor. Flax seed decreased the permeability of all drugs except verapamil. Purple loosestrife and pine decreased verapamil and metoprolol permeability. Changes caused by berries were mainly pH-related. Rosemary and oregano enhanced furosemide permeability.

Conclusions: Ingestion of extracts of herbs and berries studied are not expected to markedly change the permeabilities of highly permeable drugs. Harmful effects at sites of or during absorption are unlikely. However, if high doses of extracts are administered with low permeable drugs in vitro, effects on drug permeabilities could not be excluded. Use of such extracts should therefore be evaluated during continuous medication.
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http://dx.doi.org/10.1023/b:pham.0000045246.94064.abDOI Listing
October 2004

Permeability characteristics and membrane affinity of flavonoids and alkyl gallates in Caco-2 cells and in phospholipid vesicles.

Arch Biochem Biophys 2004 May;425(2):193-9

Viikki Drug Discovery Technology Center, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FIN-00014, Helsinki, Finland.

Biomembrane interactions of flavonoids and alkyl gallates were investigated using transport studies on Caco-2 cells and membrane affinity experiments in phospholipid vesicles. Flavone was rapidly absorbed across the cell monolayer (P(app),380 x 10(-6) cm/s), whereas efficient uptake but no apical to basolateral transport was observed with the flavonoids with higher degree of hydroxylation (e.g., quercetin and luteolin). The transport of alkyl gallates was governed by the length of the alkyl chain, i.e., methyl and propyl gallate were absorbed while octyl gallate showed cellular uptake but no transport. Flavonoids with several hydroxyl groups exhibited highest affinity for vesicle membranes, partition coefficients being 7.1 and 7.5 microM for luteolin and quercetin, respectively. In conclusion, the degree of hydroxylation, molecular configuration, and length of the side chain of flavonoids and alkyl gallates seem to have a highly important impact on their membrane affinity as well as on their permeability characteristics in Caco-2 cells.
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http://dx.doi.org/10.1016/j.abb.2004.03.023DOI Listing
May 2004

Development of LC/MS/MS methods for cocktail dosed Caco-2 samples using atmospheric pressure photoionization and electrospray ionization.

Anal Chem 2003 Nov;75(21):5969-77

Viikki Drug Discovery Technology Center (DDTC), University of Helsinki, Helsinki, Finland.

Good reliability of Caco-2 permeability studies requires competent sampling and analytical methods to ensure the comparability of day-to-day experiments. In this work, two n-in-one LC/MS/MS methods based on two different ionization techniques were developed and validated for a group of reference compounds; eight of them are recommended by the Food and Drug Administration (FDA) for the evaluation of oral drug permeability. The performance of a new ionization technique, atmospheric pressure photoionization (APPI), as an interface for quantitative LC/MS analysis was evaluated in comparison to the electrospray ionization (ESI). Generally, the validation parameters, including sensitivity, accuracy, and repeatability, were comparable for the APPI and ESI methods. The main difference was that the linear quantitative range of APPI was 3-4 orders of magnitude (r(2) >/= 0.998) whereas in ESI it was typically 2-3 orders of magnitude (r(2) >/= 0.990). By the APPI and ESI methods, the simultaneous analysis of nine highly heterogeneous compounds was achieved within 5.5-7 min, which leads to significant savings in time and cost of the analyses. The successful validation data indicate the usefulness of both the methods for the rapid and sensitive (LOD values typically
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http://dx.doi.org/10.1021/ac034679bDOI Listing
November 2003

N-in-one permeability studies of heterogeneous sets of compounds across Caco-2 cell monolayers.

Pharm Res 2003 Feb;20(2):187-97

Viikki Drug Discovery Technology Center (DDTC), Department of Pharmacy, University of Helsinki, P.O. Box 56, Fin-00014 University of Helsinki, Finland.

Purpose: The purpose of the study was to evaluate several n-in-one cocktails of heterogeneous compounds to increase the throughput of permeability studies across Caco-2 monolayers, to investigate the reliability and applicability of the method, and to develop fast and sensitive analysis for the compounds. Compounds with potential interactions in efflux and/or active transport were chosen.

Methods: Permeability experiments with verapamil, propranolol, midazolam, hydroxyzine, timolol, buspirone, procaine, naproxen, ketoprofen, and antipyrine as single compounds and in cocktails of 5-10 compounds were performed at 50 microM concentration both in the apical-to-basolateral and basolateral-to-apical direction. The compounds were quantified by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI/MS/MS). Toxicity tests were performed to determine cellular damage.

Results: The analytical method was sensitive, accurate, and rapid. The individual permeabilities of compounds in cocktails correlated well with permeabilities as single compounds. No significant interactions between the compounds within the mixtures were observed, except for acidic compounds. The studied mixtures did not show any toxicity.

Conclusions: The use of n-in-one cocktails is a suitable method to improve the capacity in routine permeability experiments and higher throughput screening of drug candidates, although potential interactions should always be borne in mind. The use of LC-ESI/MS/MS technology provides an excellent tool in fast and accurate analysis of small amounts of heterogeneous compounds.
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http://dx.doi.org/10.1023/a:1022262818573DOI Listing
February 2003

Permeability profiles of M-alkoxysubstituted pyrrolidinoethylesters of phenylcarbamic acid across caco-2 monolayers and human skin.

Pharm Res 2002 Feb;19(2):162-8

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University, Bratislava, Slovakia.

Purpose: The purpose of the present research was to study 10 m-alkoxysubstituted pyrrolidinoethylesters of phenylcarbamic acid-potential local anesthetics. The relationships between the structure of the molecule, its physicochemical parameters (log D(oct), log k, R(M), solubility) were correlated to the permeability data obtained from permeation experiments in Caco-2 monolayers and excised human skin in vitro.

Methods: The extent and mechanism(s) of permeability of the series were studied through a Caco-2 monolayer in the apical-to-basolateral (a-b) and basolateral-to-apical (b-a) directions. The MTT test was performed to determine cellular damage. In vitro transdermal permeability data were obtained from permeation experiments on excised human skin by using side-by-side chambers. Passive diffusion and iontophoretically enhanced permeability were measured.

Results: In Caco-2 monolayers, similar results in the shape of the permeability curves were obtained for the two directions. In the b-a direction, the values of P(app) were approximately 2-6 times greater than in the a-b direction. A plot of drug permeability vs. the number of carbons in the alkoxychain plateaued first, after which the permeability decreased by the increasing lipophilicity of the drug. If the log D(oct) of the ester was > or = 3.4 and the MW > 385 Da, no measurable Caco-2 permeability was found. Cell damage was also higher by the more lipophilic compounds. In excised human skin, the relationship between the passive diffusion of the drugs and the number of carbons in the alkoxychain was parabolic (r2 = 0.95). Introducing low-level electrical current (iontophoresis), transdermal permeability of the more hydrophilic phenylcarbamic acid esters increased clearly.

Conclusions: Lipophilicity and solubility of a compound have crucial roles in the permeation process. A very high lipophilicity has, however, a negative influence on the permeability, both intestinally and transdermally. Iontophoresis significantly increases the diffusion of small and less lipophilic compounds.
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http://dx.doi.org/10.1023/a:1014208515545DOI Listing
February 2002