Concentration-QTc modeling of sitravatinib in patients with advanced solid malignancies.

Sitravatinib (MGCD516) is an orally available, small molecule, tyrosine kinase inhibitor that has been evaluated in patients with advanced solid tumors. Concentration-corrected QT interval (QTc; C-QTc) modeling was undertaken, using 767 matched concentration-ECG observations from 187 patients across two clinical studies in patients with advanced solid malignancies, across a dose range of 10-200 mg, via a linear mixed-effects (LME) model. The effect on heart rate (HR)-corrected QT interval via Fridericia's correction method (QTcF) at the steady-state maximum concentration (Cmax,ss) for the sitravatinib proposed therapeutic dosing regimen (100 mg malate once daily [q.d.]) without and with relevant intrinsic and extrinsic factors were predicted. No significant changes in HR from baseline were observed. Hysteresis between sitravatinib plasma concentration and change in QTcF from baseline (ΔQTcF) was not observed. There was no significant relationship between sitravatinib plasma concentration and ΔQTcF. The final C-QTc model predicted a mean (90% confidence interval [CI]) ΔQTcF of 3.92 (1.95-5.89) ms and 2.94 (0.23-6.10) ms at the proposed therapeutic dosing regimen in patients with normal organ function (best case scenario) and patients with hepatic impairment (worst-case scenario), respectively. The upper bounds of the 90% CIs were below the regulatory threshold of concern of 10 ms. The results of the described C-QTc analysis, along with corroborating results from nonclinical safety pharmacology studies, indicate that sitravatinib has a low risk of QTc interval prolongation at the proposed therapeutic dose of 100 mg malate q.d.

A randomized, double-blind, placebo-controlled, pharmacokinetic and pharmacodynamic study of a fixed-dose combination of phentermine/topiramate in adolescents with obesity.

AIMS: To assess the pharmacokinetic (PK) and pharmacodynamic characteristics of VI-0521, a fixed-dose combination of immediate-release phentermine (PHEN) and extended-release topiramate (TPM) in adolescents aged 12 to 17 years with obesity, and to report weight loss and adverse events using this drug combination. MATERIALS AND METHODS: This was a multicentre, randomized, double-blind, parallel-design, placebo-controlled study in adolescents with obesity. A total of 42 adolescents were randomly assigned in a 1:1:1 ratio to placebo, or to a mid-dose (PHEN/TPM 7.5 mg/46 mg), or a top-dose (PHEN/TPM 15 mg/92 mg) of VI-0521. A total of 26 adolescents were included in the PK analysis (14 from the mid-dose group and 12 from the top-dose group). RESULTS: On day 56, arithmetic means of terminal elimination half-life, apparent clearance (CL/F) and apparent central volume of distribution (Vc/F) were consistent across dose levels for both PHEN and TPM. Arithmetic means of CL/F and Vc/F for PHEN and TPM administered as a combination in adolescents with obesity were within 10% to 30% of those previously assessed in adults with obesity enrolled in phase II and III studies. A higher proportion of adolescents in both the mid- and top-dose groups (13.3% and 50.0%, respectively) compared with placebo (0.0%) reached ≥5% weight loss at day 56. The least squares (LS) mean change in systolic blood pressure from baseline to day 56 was -5.2 mmHg for the placebo group, -2.5 mmHg for the mid-dose group, and - 5.5 mmHg for the top-dose group. The LS mean change in diastolic blood pressure from baseline to day 56 was -2.4 mmHg for the placebo group, +3.8 mmHg for the mid-dose group, and + 2.0 mmHg for the top-dose group. Participants in the top-dose group had increases in heart rate from baseline of 4.1 bpm, while participants in the mid-dose group experienced a mean decrease in heart rate of 4.5 bpm at day 56. Both PHEN/TPM dose combinations were safe and well tolerated. CONCLUSIONS: Treatment of adolescents with obesity using a fixed-dose combination of PHEN/TPM for 8 weeks resulted in exposure to PHEN and TPM that was comparable to that observed in adults, statistically significant weight loss, and a tolerable safety profile. These data indicate that both mid- and top-dose levels are appropriate for longer-term safety and efficacy studies in adolescents.

Population Pharmacokinetics and Exposure-Response Analyses for CPX-351 in Patients With Hematologic Malignancies.

CPX-351, a dual-drug liposomal encapsulation of cytarabine and daunorubicin at a synergistic ratio, is approved in the United States for adults with newly diagnosed therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. Population pharmacokinetics analyses were performed using nonlinear mixed-effect modeling on pooled data from 3 clinical studies, and the impact of CPX-351 exposures on efficacy and safety was assessed. The pharmacokinetics of cytarabine and daunorubicin were described using 2-compartment models with linear elimination. None of the evaluated covariates had a clinically significant impact on plasma exposure to total cytarabine or daunorubicin, while bilirubin and formulation showed statistically significant effects on pharmacokinetic parameters of cytarabine and daunorubicin, respectively. In patients with mild/moderate renal impairment or serum bilirubin ≤3 mg/dL, plasma exposures to cytarabine and daunorubicin following CPX-351 were within the variability range for patients with normal kidney function or serum bilirubin levels. Exposure-response analysis demonstrated that better efficacy outcomes were associated with higher CPX-351 exposure quartiles. Early mortality rates in all CPX-351 exposure quartiles were lower vs the 7 + 3 control group, and lower mortality rates were associated with higher exposure quartiles. A trend toward greater frequency of grade 3 treatment-emergent adverse events (but not grade 4/5 events) was observed at higher CPX-351 exposure quartiles. Overall, the population pharmacokinetic analyses indicate no adjustments to the recommended dose and schedule of CPX-351 are warranted for patients with mild/moderate renal impairment or serum bilirubin ≤3 mg/dL. Results from the exposure-response analyses suggest the current CPX-351 regimen provides a favorable risk-benefit profile.

A randomized, open-label, multicenter, phase II study evaluating the efficacy and safety of BTH1677 (1,3-1,6 beta glucan; Imprime PGG) in combination with cetuximab and chemotherapy in patients with advanced non-small cell lung cancer.

Introduction BTH1677, a 1,3-1,6 beta-glucan immunomodulator, stimulates a coordinated anti-cancer immune response in combination with anti-tumor antibody therapies. This phase II study explored the efficacy, pharmacokinetics (PK), and safety of BTH1677 combined with cetuximab/carboplatin/paclitaxel in untreated stage IIIB/IV non-small cell lung cancer (NSCLC) patients. Methods Patients were randomized 2:1 to the BTH1677 arm (N=60; BTH1677, 4 mg/kg, weekly; cetuximab, initial dose 400 mg/m2 and subsequent doses 250 mg/m2, weekly; carboplatin, 6 mg/mL/min AUC (area-under-the-curve) by Calvert formula, once each 3-week cycle [Q3W]); and paclitaxel, 200 mg/m2, Q3W) or Control arm (N=30; cetuximab/carboplatin/paclitaxel as above). Carboplatin/paclitaxel was discontinued after 4-6 cycles; patients who responded or remained stable received maintenance therapy with BTH1677/cetuximab (BTH1677 arm) or cetuximab (Control arm). Investigator and blinded central radiology reviews were conducted. Efficacy assessments included objective response rate (ORR; primary endpoint), disease control rate, duration of objective response, time-to-progression and overall survival (OS); safety was assessed by adverse events (AEs). Potential biomarker analysis for BTH1677 response was also conducted. Results Compared to control treatment, the addition of BTH1677 numerically increased ORR by both investigator (47.8% vs 23.1%; p=0.0468) and central (36.6% vs 23.1%; p=0.2895) reviews. No other endpoints differed between arms. PK was consistent with previous studies. BTH1677 was well tolerated, with AEs expected of the backbone therapy predominating. Biomarker-positive patients displayed better ORR and OS than negative patients. Conclusions BTH1677 combined with cetuximab/carboplatin/paclitaxel was well tolerated and improved ORR as first-line treatment in patients with advanced NSCLC. Future patient selection by biomarker status may further improve efficacy ClinicalTrials.gov Identifier: NCT00874848.

Modeling and Experimental Studies of Obeticholic Acid Exposure and the Impact of Cirrhosis Stage.

Obeticholic acid (OCA), a semisynthetic bile acid, is a selective and potent farnesoid X receptor (FXR) agonist in development for the treatment of chronic nonviral liver diseases. Physiologic pharmacokinetic models have been previously used to describe the absorption, distribution, metabolism, and excretion (ADME) of bile acids. OCA plasma levels were measured in healthy volunteers and cirrhotic subjects. A physiologic pharmacokinetic model was developed to quantitatively describe the ADME of OCA in patients with and without hepatic impairment. There was good agreement between predicted and observed increases in systemic OCA exposure in subjects with mild, moderate, and severe hepatic impairment, which were 1.4-, 8-, and 13-fold relative to healthy volunteers. Predicted liver exposure for subjects with mild, moderate, and severe hepatic impairment were increased only 1.1-, 1.5-, and 1.7-fold. In subjects with cirrhosis, OCA exposure in the liver, the primary site of pharmacological activity along with the intestine, is increased marginally (∼2-fold).

Population pharmacokinetic and pharmacodynamic analyses from a 4-month intradose escalation and its subsequent 12-month dose titration studies for a human monoclonal anti-FGF23 antibody (KRN23) in adults with X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is an inherited metabolic bone disease with abnormally elevated serum FGF23 resulting in low renal maximum threshold for phosphate reabsorption, low serum phosphate (Pi) and 1,25-dihydroxyvitamin D levels with subsequent development of short stature and skeletal deformities. KRN23 is a novel human anti-FGF23 antibody for the treatment of XLH. The pharmacokinetics (PK) and pharmacodynamics (PD) models of KRN23 were assessed following subcutaneous dosing every 28 days over an initial 4-month dose escalation (0.05-0.6 mg/kg) and a subsequent 12-month titration period (0.1-1.0 mg/kg) in XLH adults. The PK of KRN23 was described by a 1-compartmental model with first-order absorption and elimination at doses ≥0.1 mg/kg. The elimination half-life was 17.8 days. Covariates did not affect KRN23 PK. Mean peak serum Pi was attained 7-10 days after dosing and progressively increased following each of the initial 4 doses with comparable peak values attained following the sixth through tenth doses with a slight decrease thereafter. A PK-PD model with a maximum effect (Emax ) and a time-varying effective concentration to reach 50% of Emax (EC50,t ) described data adequately. Typical Emax was 1.5 mg/dL. Typical EC50,t was 1780 ng/mL and 5999 ng/mL after first and last dose, respectively.

The effect of plasmapheresis on blood pressure in voluntary plasma donors.

BACKGROUND AND OBJECTIVES: Donor plasmapheresis involves the removal of a weight-adjusted volume of plasma and the return of cellular components to the donor. Although plasma volume generally returns to normal, some residual effect on vital signs may be possible. This analysis was performed to determine the possible effects of plasmapheresis on blood pressure. MATERIALS AND METHODS: A 16-week study was conducted to evaluate the effects of plasma donations on cholesterol levels in healthy donors. From this study, the vital signs obtained prior to donation were analysed using statistical and dynamic analytical predictive models. RESULTS: Preliminary analyses revealed a change in systolic and diastolic blood pressure from the corresponding baseline values (Pearson Coefficient -0.44 and -0.47, respectively). Statistical models predicted a marked decrease in systolic and diastolic blood pressure following multiple donations in donors with baseline pressure in the Stage 2 hypertension range with less pronounced decreases predicted in Stage 1 donors. Little or no change in blood pressure was predicted in donors with baseline normal blood pressure or prehypertension. Dynamic models including time between donations supported these results and predicted a recovery period of about 14 days without donation in donors with Stage 2 baseline levels. CONCLUSIONS: Results suggest that systolic and diastolic blood pressure may be decreased following plasmapheresis used for plasma donations at intervals of <14 days in donors with high baseline blood pressure levels.

Modeling and simulation for medical product development and evaluation: highlights from the FDA-C-Path-ISOP 2013 workshop.

Medical-product development has become increasingly challenging and resource-intensive. In 2004, the Food and Drug Administration (FDA) described critical challenges facing medical-product development by establishing the critical path initiative [1]. Priorities identified included the need for improved modeling and simulation tools, further emphasized in FDA's 2011 Strategic Plan for Regulatory Science [Appendix]. In an effort to support and advance model-informed medical-product development (MIMPD), the Critical Path Institute (C-Path) [www.c-path.org], FDA, and International Society of Pharmacometrics [www.go-isop.org] co-sponsored a workshop in Washington, D.C. on September 26, 2013, to examine integrated approaches to developing and applying model- MIMPD. The workshop brought together an international group of scientists from industry, academia, FDA, and the European Medicines Agency to discuss MIMPD strategies and their applications. A commentary on the proceedings of that workshop is presented here.

Pharmacokinetic and pharmacodynamic modeling to determine the dose of ST-246 to protect against smallpox in humans.

Although smallpox has been eradicated, the United States government considers it a "material threat" and has funded the discovery and development of potential therapeutic compounds. As reported here, the human efficacious dose for one of these compounds, ST-246, was determined using efficacy studies in nonhuman primates (NHPs), together with pharmacokinetic and pharmacodynamic analysis that predicted the appropriate dose and exposure levels to provide therapeutic benefit in humans. The efficacy analysis combined the data from studies conducted at three separate facilities that evaluated treatment following infection with a closely related virus, monkeypox virus (MPXV), in a total of 96 NHPs. The effect of infection on ST-246 pharmacokinetics in NHPs was applied to humans using population pharmacokinetic models. Exposure at the selected human dose of 600 mg is more than 4-fold higher than the lowest efficacious dose in NHPs and is predicted to provide protection to more than 95% of the population.

Phase I safety, pharmacokinetic and pharmacodynamic trial of BMS-599626 (AC480), an oral pan-HER receptor tyrosine kinase inhibitor, in patients with advanced solid tumors.

PURPOSE: We studied the safety, tolerability, and recommended dose of BMS-599626, an orally bioavailable inhibitor of the human epidermal growth factor receptor (HER) family of receptor tyrosine kinases. PATIENTS AND METHODS: Patients with advanced solid tumors that expressed epidermal growth factor receptor (EGFR) and/or HER-2 were recruited and enrolled in a phase I, open-label, dose escalation trial of oral BMS-599626 starting at 100 mg/day given once daily for at least 28 days. RESULTS: Forty-five patients received BMS-599626 (100-660 mg/day). Dose-limiting toxic effects were reported at 660 mg/day (grade 3 elevation of hepatic transaminases [two patients] and QTc interval prolongation [one patient]), therefore the recommended maximum tolerated dose was 600 mg/day. The most frequent drug-related toxic effects were diarrhea (30% of patients), anorexia (13%), asthenia (30%), and cutaneous toxic effects, including skin rash (30%). Pharmacokinetic analysis demonstrated C(max) and exposure to BMS-599626 in patients increased with dose. Eleven patients had stable disease and received BMS-599626 for ≥ 4 months. Serial skin and tumor biopsies taken before and after treatment revealed expected changes in pharmacodynamic biomarkers, indicating that the EGFR and HER-2 pathways were affected. Positron emission tomography imaging showed a metabolic response in 2 of 10 patients evaluated. CONCLUSION: BMS-599626 was generally well tolerated, with disease stabilization across a range of tumor types and doses.

Ammonia control in children with urea cycle disorders (UCDs); phase 2 comparison of sodium phenylbutyrate and glycerol phenylbutyrate.

UNLABELLED: Twenty four hour ammonia profiles and correlates of drug effect were examined in a phase 2 comparison of sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB or HPN-100), an investigational drug being developed for urea cycle disorders (UCDs). STUDY DESIGN: Protocol HPN-100-005 involved open label fixed-sequence switch-over from the prescribed NaPBA dose to a PBA-equimolar GPB dose with controlled diet. After 7 days on NaPBA or GPB, subjects underwent 24-hour blood sampling for ammonia and drug metabolite levels as well as measurement of 24-hour urinary phenyacetylglutamine (PAGN). Adverse events (AEs), safety labs and triplicate ECGs were monitored. RESULTS: Eleven subjects (9 OTC, 1 ASS, 1 ASL) enrolled and completed the switch-over from NaPBA (mean dose=12.4 g/d or 322 mg/kg/d; range=198-476 mg/kg/d) to GPB (mean dose=10.8 mL or 0.284 mL/kg/d or 313 mg/kg/d; range=192-449 mg/kg/d). Possibly-related AEs were reported in 2 subjects on NaPBA and 4 subjects on GPB. All were mild, except for one moderate AE of vomiting on GPB related to an intercurrent illness. No clinically significant laboratory or ECG changes were observed. Ammonia was lowest after overnight fast, peaked postprandially in the afternoon to early evening and varied widely over 24h with occasional values >100 µmol/L without symptoms. Ammonia values were ~25% lower on GPB vs. NaPBA (p≥0.1 for ITT and p<0.05 for per protocol population). The upper 95% confidence interval for the difference between ammonia on GPB vs. NaPBA in the ITT population (95% CI 0.575, 1.061; p=0.102) was less than the predefined non-inferiority margin of 1.25 and less than 1.0 in the pre-defined per-protocol population (95% CI 0.516, 0.958; p<0.05). No statistically significant differences were observed in plasma phenylacetic acid and PAGN exposure during dosing with GPB vs. NaPBA, and the percentage of orally administered PBA excreted as PAGN (66% for GPB vs. 69% for NaPBA) was very similar. GPB and NaPBA dose correlated best with urinary-PAGN. CONCLUSIONS: These findings suggest that GPB is at least equivalent to NaPBA in terms of ammonia control, has potential utility in pediatric UCD patients and that U-PAGN is a clinically useful biomarker for dose selection and monitoring.

Phase 2 comparison of a novel ammonia scavenging agent with sodium phenylbutyrate in patients with urea cycle disorders: safety, pharmacokinetics and ammonia control.

UNLABELLED: Glycerol phenylbutyrate (glyceryl tri (4-phenylbutyrate)) (GPB) is being studied as an alternative to sodium phenylbutyrate (NaPBA) for the treatment of urea cycle disorders (UCDs). This phase 2 study explored the hypothesis that GPB offers similar safety and ammonia control as NaPBA, which is currently approved as adjunctive therapy in the chronic management of UCDs, and examined correlates of 24-h blood ammonia. METHODS: An open-label, fixed sequence switch-over study was conducted in adult UCD patients taking maintenance NaPBA. Blood ammonia and blood and urine metabolites were compared after 7 days (steady state) of TID dosing on either drug, both dosed to deliver the same amount of phenylbutyric acid (PBA). RESULTS: Ten subjects completed the study. Adverse events were comparable for the two drugs; 2 subjects experienced hyperammonemic events on NaPBA while none occurred on GPB. Ammonia values on GPB were approximately 30% lower than on NaPBA (time-normalized AUC=26.2 vs. 38.4 micromol/L; Cmax=56.3 vs. 79.1 micromol/L; not statistically significant), and GPB achieved non-inferiority to NaPBA with respect to ammonia (time-normalized AUC) by post hoc analysis. Systemic exposure (AUC(0-24)) to PBA on GPB was 27% lower than on NaPBA (540 vs. 739 microgh/mL), whereas exposure to phenylacetic acid (PAA) (575 vs. 596 microg h/mL) and phenylacetylglutamine (PAGN) (1098 vs. 1133 microg h/mL) were similar. Urinary PAGN excretion accounted for approximately 54% of PBA administered for both NaPBA and GPB; other metabolites accounted for <1%. Intact GPB was generally undetectable in blood and urine. Blood ammonia correlated strongly and inversely with urinary PAGN (r=-0.82; p<0.0001) but weakly or not at all with blood metabolite levels. CONCLUSIONS: Safety and ammonia control with GPB appear at least equal to NaPBA. Urinary PAGN, which is stoichiometrically related to nitrogen scavenging, may be a useful biomarker for both dose selection and adjustment for optimal control of venous ammonia.

Clinical trial simulations in pediatric patients using realistic covariates: application to teduglutide, a glucagon-like peptide-2 analog in neonates and infants with short-bowel syndrome.

Teduglutide, a synthetic glucagon-like peptide-2 (GLP-2) analog with activity relating to the regeneration, maintenance, and repair of the intestinal epithelium, is currently being evaluated for the treatment of short-bowel syndrome (SBS), Crohn's disease, and other gastrointestinal disorders. On the basis of promising results from teduglutide studies in adults with SBS and from studies in neonatal and juvenile animal models, a pediatric multiple-dose phase I clinical study was designed to determine the safety, efficacy, and pharmacokinetics of teduglutide in pediatric patients with SBS who have undergone resection for necrotizing enterocolitis, malrotation, or intestinal atresia. This report details the application of clinical trial simulations coupled with a novel approach using generalized additive modeling for location, scale, and shape (GAMLSS) that facilitates the simulation of demographic covariates specific to the targeted patient populations. The goal was to optimize phase I dosing strategies and the likelihood of achieving target exposure and therapeutic effect.

Pharmacodynamic equivalence of two orlistat capsule formulations in healthy volunteers under fed conditions.

OBJECTIVE: Orlistat is a reversible lipase inhibitor for obesity management. Orlistat exerts its pharmacological activity in the lumen of the stomach and small intestine by binding with the active site of gastric and pancreatic lipases, with the consequent inhibition of the systemic absorption of dietary fat. The undigested triglycerides are not absorbed, resulting in caloric deficit and positive effect in weight control. The objective of this study was to assess, using fat excreted in feces, the pharmacodynamic equivalence of orlistat when administered as generic and innovator capsule formulations. MATERIALS AND METHODS: A total of 18 healthy volunteers (12 males and 6 females) followed a 5-day run-in diet period in order to become accustomed to a high fat diet. Subjects were then randomized to receive under fed conditions oral doses of orlistat (120 mg) 3 times daily for 10 consecutive days as the generic (Ranbaxy Laboratories) or innovator (Xenical, Roche Laboratories, Nutley, NJ, USA) capsule formulations. Subjects followed a standardized diet (2,500 kcal/day, 30% as fat) for the entire study. Feces were collected over the last 2 days of the run-in period (baseline) and over the last 5 days of the 2 treatment periods. The amount of fat in meals and feces was assayed with a limit of detection of 0.1 and 0.2%, respectively. Fecal fat excretion over 24 hours (FFE(24), calculated as the percentage of amount of fat excreted in feces relative to the amount of fat ingested) was used as a pharmacodynamic endpoint to assess the therapeutic equivalence between the 2 orlistat formulations. An analysis of variance (ANOVA) was performed on FFE(24) parameters. RESULTS: Mean FFE(24) values at baseline and after repeated oral administrations of the generic and innovator formulations of orlistat were 6.48, 20.0 and 19.6%, respectively. The ratio of least-squares means (LSM) of FFE(24) of the generic to the innovator formulation was 99.1%, with 90% confidence intervals of 83.8 -114.5%. Adverse events for the generic and innovator products were similar in nature and frequency. CONCLUSION: Mean FFE(24) values were used as pharmacodynamic endpoints to assess equivalence between 2 formulations of orlistat. Results from this study suggest that pharmacodynamics of the generic capsule formulation of orlistat were similar to the marketed capsule formulation based on FFE(24) values.

Pharmacokinetics of lamivudine, zidovudine, and nevirapine administered as a fixed-dose combination formulation versus coadministration of the individual products.

The pharmacokinetics of 150 mg lamivudine, 300 mg zidovudine, and 200 mg nevirapine were assessed following single oral administration of a fixed-dose combination tablet and coadministration of the separate innovator products in healthy male subjects (n = 64) under fasting conditions in an open-label, randomized, 2-way crossover study. Multiple blood samples were collected up to 72 hours and plasma concentrations of antiretrovirals were assayed using liquid chromatography/tandem mass spectrometry methods. Pharmacokinetic parameters were calculated using noncompartmental methods, and bioequivalence was assessed using an analysis of variance model. The ratio of the least squares mean (fixed-dose combination to individual products) and 90% confidence intervals of AUC(0-t), AUC(0-infinity), and C(max) for lamivudine, zidovudine, and nevirapine were all within 80.0% to 125.0%, suggesting a similar rate and extent of antiretroviral exposure in the bloodstream. Mean oral clearance (CL/F) values of lamivudine, zidovudine, and nevirapine for the fixed-dose combination were 23.7, 127, and 1.65 L/h, respectively. The fixed-dose combination and individual products were equally safe and well tolerated, with only a few subjects experiencing drug-related adverse events. The current fixed-dose combination of lamivudine, zidovudine, and nevirapine is expected to provide a similar efficacy/safety profile as coadministration of the individual products, a better adherence to treatment, and considerable cost savings in the treatment of HIV.

Pharmacokinetics and anesthetic activity of eugenol in male Sprague-Dawley rats.

Eugenol, the principle chemical constituent of clove oil, has recently been evaluated for its anesthetic and analgesic properties in fish and amphibians. The objective of this study was to determine the pharmacokinetic (PK) and anesthetic activity of eugenol in rats. Male Sprague-Dawley rats received single i.v. doses of eugenol (0, 5, 10, 20, 40 and 60 mg/kg) and anesthetic level was evaluated with the withdrawal reflex. For the 20 mg/kg dose level, blood and urinary samples were collected over 1 h for the PK assessment. Plasma and blood concentrations of eugenol, as well as metabolite identification in urine, were determined using a novel dansyl chloride derivatization method with liquid chromatography mass spectrometry (LC/MS/MS). PK parameters were calculated using noncompartmental methods. Eugenol-induced loss of consciousness in a dose-dependent manner, with mean (+/-SEM) recovery in reflex time of 167 +/- 42 sec observed at the highest dose level. Mean systemic clearance (Cl) in plasma and blood were 157 and 204 mL/min/kg, respectively. Glucuronide and sulfate conjugates were identified in urine. Overall, eugenol produced a reversible, dose-dependent anesthesia in male Sprague-Dawley rats.

Bioequivalence of abacavir generic and innovator formulations under fasting and fed conditions.

OBJECTIVE: Abacavir sulfate is a synthetic carbocyclic nucleoside analogue indicated for the treatment of HIV-1 infection in combination with other antiretroviral agents. The objective of the current study was to determine the bioequivalence between a generic formulation of abacavir and the innovator product. MATERIAL AND METHODS: A total of 80 subjects were randomly assigned to receive a single 300 mg oral dose of abacavir sulfate as the generic (Ranbaxy-Abacavir, Ranbaxy Laboratories Ltd., equivalent to 300 mg of abacavir) and innovator (Ziagen, GlaxoSmithKline) tablet formulations in 2-way crossover studies performed under fasting (n=40) and fed (n=40) conditions. Multiple blood samples were collected over 14 hours and plasma concentrations of abacavir were assayed using an LC/MS/MS method with a limit of quantitation of 25.0 ng/ml. Pharmacokinetic (PK) parameters were calculated using noncompartmental methods. RESULTS: Under fasting conditions, geometric mean area under the curve from time 0 to the last measurable concentration (AUC(0-t)), area under the curve extrapolated to infinity (AUC(0-infinity) and maximum plasma concentrations (Cmax) of abacavir for the generic (5565 ng x h/ml, 5668 ng x h/ml and 2526 ng/ml, respectively) and innovator (5675 ng x h/ml, 5770 ng x h/ml and 2528 ng/ml, respectively) products were very similar. Under fed conditions, mean values of AUC(0-t) AUC(0-infinity) and Cmax for the generic (4487 ng x h/ml, 4571 ng x h/ml and 1841 ng/ml, respectively) and innovator (4574 ng x h/ml, 4654 ng x h/ml and 1781 ng/ml, respectively) formulations were also very similar. Ratios of LSM and 90% confidence intervals of PK parameters between the 2 formulations were within 80.0 - 125.0% under fasting and fed conditions, suggesting that the 2 tablet formulations resulted in similar rate and extent of bioavailability. Adverse events for the generic and innovator products were similar in nature and frequency in the fasting and fed studies. CONCLUSIONS Based on the above results, the generic tablet formulation of abacavir developed by Ranbaxy should be equally effective as the innovator product.

Comparative bioavailability study of zidovudine administered as two different tablet formulations in healthy adult subjects.

AIM: Zidovudine is a synthetic nucleoside analogue of thymidine with activity against the human immunodeficiency virus type 1 (HIV-1). In patients with HIV infections or the acquired immunodeficiency syndrome (AIDS), zidovudine is a first-line therapy that was shown to reduce morbidity, mortality, and hospitalization. A generic formulation of zidovudine offers the possibility of considerable savings to HIV/AIDS patients in developed and Third World countries. The objective of the current study was to characterize the pharmacokinetic and safety profiles of zidovudine administered as a generic tablet formulation relative to the innovator product. VOLUNTEERS AND METHODS: A total of 68 healthy adult volunteers received a 300 mg oral dose of zidovudine as the generic formulation (AVIRO-Z 300 mg tablet, Ranbaxy Laboratories Limited) and as the innovator product (Retrovir tablet, GlaxoSmithKline) in a randomized, 2-way crossover study. Multiple blood samples were collected over 12 hours and plasma concentrations of zidovudine were assayed using an LC/MS/MS method with an analytical range of 5.00 to 2,000 ng/ml. Pharmacokinetic parameters were calculated using non-compartmental methods. RESULTS: Mean plasma concentrations of zidovudine declined in a mono-exponential manner, with mean concentration values falling below the limit of quantitation 12 hours after administration of both formulations. Mean area under the curve from time 0 to the last measurable concentration (AUC(0-t)), mean area under the curve from time 0 to infinity (AUC(0-infinity)) and peak plasma concentrations (C(max)) of zidovudine for the generic tablet formulation (2,220.6 ng x h/ml, 2,236.0 ng x h/ml and 1,087.9 ng/ml, respectively) were very similar to those observed for the innovator product (2,139.7 ng x h/ml, 2,158.6 ng x h/ml and 1,066.5 ng/ml, respectively). Ratios of least-squares means and 90% confidence intervals of AUC(0-t) AUC(0-infinity) and C(max) between the 2 formulations were within 80-125%, suggesting that the two tablet formulations displayed similar rate and extent of bioavailability. The oral clearance (CL/F) of zidovudine for the generic and innovator formulations were 2.11 1/h/kg and 2.16 1/h/kg, respectively. For the two formulations, adverse events were similar in nature and frequency. CONCLUSION: Since the two formulations displayed similar in vivo delivery rate of zidovudine in the bloodstream, the generic tablet formulation of zidovudine developed by Ranbaxy should be equally effective as the innovator product and is expected to produce considerable cost-savings in AIDS patients worldwide.

Comparative bioavailability of a generic capsule formulation of the reverse transcriptase inhibitor efavirenz and the innovator product.

OBJECTIVE: Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that has been used successfully for more than a decade to treat human immunodeficiency virus (HIV) infection. The objective of the current study was to determine the bioequivalence between a generic capsule formulation of efavirenz and the innovator product. MATERIAL AND METHODS: A total of 41 healthy subjects (34 males and 8 females) received a single 200 mg oral dose of efavirenz as the generic (Ranbaxy-Efavirenz, Ranbaxy Laboratories Ltd.) and innovator (Sustiva, Bristol-Myers Squibb) capsule formulations under fasting conditions in a randomized, 2-way crossover study. Multiple blood samples were collected over 72 hours and plasma concentrations of efavirenz were assayed using an LC/MS/MS method. Pharmacokinetic (PK) parameters were calculated using non-compartmental methods. RESULTS: Plasma concentrations of efavirenz peaked within 2.5 hours and then declined in a multi-exponential manner for both formulations. At 72 hours post dose, all plasma concentrations of efavirenz were above the LOQ of the assay (10 ng/ml). Mean area under the curve from 0 - 72 hours (AUC0-72) and maximum plasma concentrations (Cmax) of efavirenz for the generic capsule formulation were 22,840 ng x h/ml and 1,199 ng/ml, respectively. Ratios and 90% confidence intervals of PK parameters between the two formulations were within 80.0 - 125.0%, suggesting that the two capsule formulations resulted in similar rate and extent of bioavailability under fasting conditions. Adverse events were similar in nature and frequency for the two formulations. CONCLUSIONS: Based on the above results, the generic capsule formulation of efavirenz developed by Ranbaxy should be as effective as the innovator product.