Publications by authors named "Partha Nandy"

36 Publications

Pharmacometrics-based dose selection of levofloxacin as a treatment for postexposure inhalational anthrax in children.

Antimicrob Agents Chemother 2010 Jan 26;54(1):375-9. Epub 2009 Oct 26.

Division of Pharmacometrics, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, Maryland, USA.

Levofloxacin was recently (May 2008) approved by the U.S. Food and Drug Administration as a treatment for children following inhalational exposure to anthrax. Given that no clinical trials to assess the efficacy of a chosen dose was conducted, the basis for the dose recommendation was based upon pharmacometric analyses. The objective of this paper is to describe the basis of the chosen pediatric dose recommended for the label. Pharmacokinetic (PK) data from 90 pediatric patients receiving 7 mg/kg of body weight levofloxacin and two studies of 47 healthy adults receiving 500 and 750 mg/kg levofloxacin were used for the pharmacometric analyses. Body weight was found to be a significant covariate for levofloxacin clearance and the volume of distribution. Consistently with developmental physiology, clearance also was found to be reduced in pediatric patients under 2 years of age due to immature renal function. Different dosing regimens were simulated to match adult exposure (area under the concentration-time curve from 0 to 24 h at steady state, maximum concentration of drug in serum at steady state, and minimum concentration of drug in serum at steady state) following the approved adult dose of 500 mg once a day. The recommended dose of 8 mg/kg twice a day was found to match the exposure of the dose approved for adults in a manner that permitted confidence that this dose in children would achieve efficacy comparable to that of adults.
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http://dx.doi.org/10.1128/AAC.00667-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2798547PMC
January 2010

Pharmacodynamic profiling of ceftobiprole for treatment of complicated skin and skin structure infections.

Antimicrob Agents Chemother 2009 Aug 15;53(8):3371-4. Epub 2009 Jun 15.

Johnson & Johnson Pharmaceutical Research & Development, LLC, 920 Route 202 South, Raritan, NJ 08869, USA.

Ceftobiprole, a broad-spectrum cephalosporin with activity against methicillin (meticillin)-resistant staphylococci, was statistically noninferior to a combination of vancomycin plus ceftazidime in patients with complicated skin and skin structure infections (cSSSI). This analysis used data from this clinical trial to determine the relationship between therapeutic outcome and the percentage of time that the unbound ceftobiprole concentration exceeds the MIC (percent T>MIC). From the trial of ceftobiprole (500 mg every 8 h, 2-h infusion) for cSSSI due to gram-positive and/or gram-negative bacteria, data from 309 patients in the microbiological intent-to-treat analysis set with measured ceftobiprole concentrations and baseline MICs were used to assess the relationship between percent T>MIC and therapeutic outcome. Individual pharmacokinetic (PK) profiles were obtained from a three-compartment population PK model. The relationship between percent T>MIC and a clinical cure was determined. For the clinical trial dosing regimen, individual percent T>MICs were used to calculate fractional target attainment rates (TARs) for >or=30 and >or=50% T>MIC targets at various MICs. There was a statistically significant relationship between achieving a >or=30 or >or=50% T>MIC and a clinical cure (P = 0.003 and P = 0.007, respectively; Pearson's chi(2) test). The fractional TAR was greater than 90% at a MIC of MIC and a clinical cure with ceftobiprole was demonstrated. A ceftobiprole regimen of 500 mg every 8 h as a 2-h infusion has a high probability of achieving a target of >or=30 or >or=50% T>MIC for patients with cSSSI due to gram-positive and gram-negative pathogens.
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http://dx.doi.org/10.1128/AAC.01653-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2715635PMC
August 2009

Model-based approach to characterize efavirenz autoinduction and concurrent enzyme induction with carbamazepine.

Antimicrob Agents Chemother 2009 Jun 17;53(6):2346-53. Epub 2009 Feb 17.

Research and Development, Bristol-Myers Squibb, P.O. Box 4000, Princeton, NJ 08543-4000, USA.

Characterization of the time course and magnitude of enzyme induction due to multiple inducers is important for interpretation of clinical data from drug-drug interaction studies. A population interaction model was developed to quantify efavirenz autoinduction and further induction with concurrent carbamazepine coadministration. Efavirenz concentration data in the absence and presence of carbamazepine following single- and multiple-dose oral administrations in healthy subjects were used for model development. The proposed model was able to describe the time-dependent efavirenz autoinduction and the further induction with carbamazepine when the agents were combined. The estimated population averages of efavirenz oral clearance were 5.5, 9.4, 14.4, and 16.7 liters/h on days 1, 14, and 35 and at steady state for the interaction, respectively, for efavirenz monotherapy for 2 weeks followed by the coadministration of carbamazepine for 3 weeks. The estimated times to 50% of the steady state for efavirenz autoinduction and for the induction resulting from the concurrent administration of efavirenz and carbamazepine were similar (around 10 to 12 days). With this model-based analysis, efavirenz exposures can be projected prior to and at the steady state of induction, allowing a better understanding of the time course and magnitude of enzyme induction.
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http://dx.doi.org/10.1128/AAC.01120-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2687212PMC
June 2009

Population pharmacokinetic analysis of ceftobiprole for treatment of complicated skin and skin structure infections.

Antimicrob Agents Chemother 2009 Mar 15;53(3):1228-30. Epub 2008 Dec 15.

Johnson & Johnson Pharmaceutical Research & Development, LLC, South Raritan, NJ 08869, USA.

Population pharmacokinetic analysis demonstrated that renal function, as assessed by creatinine clearance (CL(CR)), was the patient characteristic that had a clinically relevant impact on ceftobiprole pharmacodynamics. Dosing adjustments based on CL(CR) for subjects with renal impairment should provide ceftobiprole exposure similar to that in patients with normal renal function.
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http://dx.doi.org/10.1128/AAC.00632-08DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2650522PMC
March 2009

A model to evaluate the pharmacokinetic and pharmacodynamic variables of extended-release products using in vivo tissue microdialysis in humans: bupivacaine-loaded microcapsules.

Anesth Analg 2003 Jul;97(1):124-31, table of contents

Department of Anesthesiology, Virginia Mason Clinic, Seattle, Washington 98111, USA.

Unlabelled: Biodegradable microcapsules produce an ultra-long duration of local anesthesia. We hypothesized that this duration is caused by the sustained-release of bupivacaine from the microcapsules into the surrounding tissue. Previous studies investigated the pharmacokinetics (PKs) of bupivacaine after release from microcapsules and absorption into the systemic circulation. Microdialysis sampling can determine the PKs of any drug at its site of injection. This study was performed to characterize the PKs of bupivacaine and dexamethasone released from microcapsules at a subcutaneous injection site over a 96-h period in volunteers. Bupivacaine concentrations were compared with clinical variables of local anesthetic blockade. This study demonstrates that bupivacaine is released in a sustained manner from microcapsules, that bupivacaine concentrations increase for 24-34 h after microcapsule injection, and that analgesia parallels the tissue bupivacaine concentration obtained by microdialysis. Analgesia was equally rapid in onset with aqueous and microcapsule bupivacaine (P = 0.23). Analgesia was still present at 78% of microcapsule-injected sites after 96 h, significantly longer than for aqueous bupivacaine (P < 0.001). Mild pruritus was the most common side effect, occurring with 56% of the microcapsule injections. Dexamethasone-containing bupivacaine microcapsules are well tolerated and produce a prolonged duration of skin analgesia. Systemic absorption of bupivacaine produces higher peak plasma levels after aqueous injection than after microcapsule injection, despite the injection of a threefold larger load of bupivacaine in the latter.

Implications: Microcapsules loaded with bupivacaine and dexamethasone and administered by subcutaneous injection produce prolonged cutaneous anesthesia and analgesia. Determination of local tissue pharmacokinetic variables of bupivacaine by microdialysis confirms that the prolonged duration of anesthesia is caused by the extended release characteristics of the microcapsules.
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http://dx.doi.org/10.1213/01.ane.0000067531.49000.c1DOI Listing
July 2003

The dose response and effects of dexamethasone on bupivacaine microcapsules for intercostal blockade (T9 to T11) in healthy volunteers.

Anesth Analg 2003 Feb;96(2):576-82, table of contents

Department of Anesthesiology, Virginia Mason Clinic, Seattle, Washington, 98111 USA.

Biodegradable microcapsules containing bupivacaine/dexamethasone produce an anesthetic duration of 7-11 days in animal models. In this investigation, we explored the effect of increasing doses (Part 1) and the effect of including dexamethasone (Part 2) on the onset, density, and duration of analgesia and anesthesia produced by bupivacaine microcapsules. Concentrations ranging from 0.3125% to 5.0% in microcapsules were compared with 0.25% aqueous bupivacaine (bilateral injection, three intercostal nerves, 2 mL per nerve) (Part 1). Part 2 compared 2.5% microcapsules with or without the inclusion of dexamethasone by unilateral blockade. Sensory block was assessed by pinprick, temperature sensation, and subjective numbness (0, not numb; 10, totally numb). Pharmacodynamic assessments and plasma drug concentrations of bupivacaine and dexamethasone were measured for 96 h. The onset time was reduced and the duration of analgesia increased over the 0.3125%-5.0% dose range (P < 0.02). Onset with 2.5% microcapsules approximated that of 0.25% aqueous bupivacaine. Microcapsule block duration increased to at least 96 h and was significantly longer than aqueous bupivacaine (P < 0.001). Inclusion of dexamethasone increased the duration of pinprick anesthesia in 2.5% microcapsules (P = 0.03). We conclude that bupivacaine/dexamethasone microcapsules are well tolerated and demonstrate a dose-related effect in onset and duration of intercostal blockade. Inclusion of dexamethasone increases intercostal block anesthesia.
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http://dx.doi.org/10.1097/00000539-200302000-00050DOI Listing
February 2003
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