Development and validation of liquid chromatography-tandem mass spectrometric method for quantification of meropenem in rat plasma and its application in a preclinical dose proportionality study.

A simple, rapid, sensitive and selective assay based liquid chromatography-tandem mass spectrometric method was developed and validated for quantitative analysis of meropenem in rat plasma using rolipram as internal standard. Efficient chromatographic separation of analyte from matrix components was achieved by using Kromasil 100 C18 (150×4.6 mm, 5 µm) reversed phase column with mobile phase consisting of acetonitrile and 2 mM ammonium acetate buffer (80:20, v/v) delivered in isocratic mode with constant flow rate of 0.7 mL/min. Detection of meropenem and rolipram was performed in positive mode using multiple reaction monitoring (MRM). The mass transitions 384.1→141.0 and 276.2→191.1 were used to quantify meropenem and rolipram, respectively. A fast and simple solid phase extraction method was optimized for extraction of meropenem from rat plasma. The developed method was validated for selectivity, accuracy, precision, linearity, recovery, stability, matrix effect, dilution integrity as per regulatory guidelines. The developed method was selective with no interfering components at the retention time of meropenem and rolipram. The assay demonstrated acceptable linearity (R(2)>0.99) over a dynamic range of 0.19-201.40 µg/mL. The method exhibited excellent and acceptable precision and accuracy, and produced consistent recoveries. The method demonstrated excellent stability of meropenem in rat plasma under studied conditions investigated. Finally, the validated method was successfully applied to quantify meropenem levels in rat plasma of a dose escalation study.

Bioequivalence and pharmacokinetic comparison of 3 metformin extended/sustained release tablets in healthy Indian male volunteers.

This study was undertaken to compare the bioavailability and pharmacokinetic properties of 3 marketed product of metformin (CAS 1115-70-4) extended/sustained release formulation in Indian male volunteers. Study was designed as an open-label, randomized, 3-treatment, single-dose, crossover, bioavailability study comparing 3 marketed brands of 500 mg metformin extended/sustained release tablets in 18 healthy human male volunteers under fed condition. A single oral dose of 500 mg metformin sustained release products, test A (Glycomet SR), test B (Bigomet SR) and extended release reference product was administered as per computer generated randomization schedule during 3 period of the study having 7 days of washout period. A liquid Chromatography mass spectroscopy method for the determination of metformin in human plasma was developed and validated using metformin-D6 as an internal standard. A noncompartment pharmacokinetic method was employed to determine the pharmacokinetic parameters (Cmax, Tmax, AUC0-t, AUC0-∞ and t½) of metformin using WinNonlin-Node 4.0 software. Cmax, AUC0-t and AUC0-∞ were used to test for bioequivalence after log transformation of plasma data. The predetermined regulatory range of 90% CI for bioequivalence was 0.80 to 1.25. The 90% confidence intervals for log transformed data for Cmax, AUC0-t and AUC0-∞ for test A vs. reference were 82.11-98.91, 86.29-102.17 and 86.34-102.59 respectively whereas for test B vs. reference were 104.39-125.76, 94.78-112.22 and 92.85-110.33 respectively. The results of this study suggest that the test A was bioequivalent to reference product, whereas test B was not as per regulatory defined criteria.

Pharmacokinetic-pharmacodynamic equivalence of three gliclazide formulations in healthy human male subjects.

AIMS: To find out the pharmacokinetic (PK) and pharmacodynamic (PD) parameters for assessing the bioequivalence of three marketed products. To study the relationship between the pharmacokinetics of gliclazide and pharmacodynamic effect in healthy male volunteers. METHODS: This was an open label, balanced, randomized, 3-treatment, 3-sequence, 3 period, single-dose, cross-over bioavailability study in which 18 healthy adults were randomized to receive gliclazide 80 mg with 7 days wash out between treatments. The drug was administered with 240 ml of 20% glucose solution after a 10 h overnight fasting. Pharmacokinetic parameters like t(max), C(max), AUC(0-t), AUC(0-∞), AUC(0-t) / AUC(0-∞) and t(1/2) and pharmacodynamic parameters like maximum effect (minimum glucose level in the body, C(minglu)), time to minimum glucose level in the body (T(cminglu)) and partial AUC were calculated for all the products. RESULTS: The values for mean ± SD for age, height and weight of the volunteers were 28.00 ± 22.68, 165.78 ± 5.56 and 56.78 ± 13.37 respectively. There were total 4 withdrawn subjects and 1 drop out. Within batch accuracy of the method were in the range of 95.5 - 101.7%, 99.1 - 106.1% and 96.2 - 104.2% for three consecutive batches. The 90% CI for log transformed data of the PK and PD were within the acceptance range of 80.0 - 125.0%. CONCLUSIONS: This population PKPD analysis has characterized the relationship between the exposure to gliclazide and its hypoglycemic effect. The test products A & B compared to reference product R were bioequivalent on the basis of pharmacokinetic and pharmacodynamic parameters. Finally it is recommended that the more costly product R can be safely switched with less costly products i.e. A and B.

A pharmacokinetic and bioequivalence study of Contiflo ICON 400 µg tablets in healthy Indian subjects.

INTRODUCTION: Tamsulosin, an alpha1 adrenoceptor blocking agent, exhibits selectivity for alpha1 receptors in human prostate. Blockade of these adrenoceptors can cause smooth muscles in the bladder neck and prostate to relax, resulting in an improvement in urine flow rate and a reduction in symptoms of benign prostatic hypertrophy. A new formulation Contiflo ICON 400 µg has been developed by Ranbaxy Laboratories Limited, India similar to Flomaxtra XL 400 µg of Astellas Pharma Limited, United Kingdom. This product is specifically designed to achieve a more consistent plasma concentration over a period of 24-h, a lower maximum plasma concentration (Cmax) and an independence of pharmacokinetics (PKs) on food intake. METHODS: The objective of the present study was to evaluate the pharmacokinetics and bioequivalence of the new formulation Contiflo ICON 400 µg of Ranbaxy Laboratories Limited, India and Flomaxtra XL 400 µg prolonged release tablets (containing tamsulosin hydrochloride prolonged release 400 µg) of Astellas Pharma Limited, United Kingdom. Study was conducted as an open label, balanced, randomized, two-treatment, two-period, two-sequence, cross over, single-dose bioequivalence study in 32 adult male human subjects under fed conditions. The mean (range) age, weight and height of the study subjects were 27.03 years (19 - 40 years), 57.19 kg (48 - 72 kg) and 166.81 cm (154 - 181 cm) respectively. Blood samples were collected at pre-dose and at 0.5, 1, 2, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 12, 16, 20, 24, 36, 48, 72, and 96 h post dose in each period. Plasma samples were analyzed for tamsulosin by using validated liquid chromatographic mass spectrometry (LC-MS/MS) method. RESULTS: The Mean ± SD of pharmacokinetic parameters tmax, Cmax, AUC24, AUClast and AUCinf for Tamsulosin were 11.741 ± 4.7201 and 12.155 ± 6.3077 h, 10.7614 ± 4.76709 and 10.4954 ± 5.08979 ng/ml, 171.4674 ± 77.39695 and 160.6738 ± 77.98628 ng.h/ml, 262.7771 ± 150.21432 and 250.6854 ± 156.75581 ng.h/ml, 280.0702 ± 152.14253 and 273.5078 ± 156.85910 ng.h/ml for test and reference formulations respectively. The ratios of least square means and the 90% confidence interval of log transformed pharmacokinetic parameter Cmax, AUC24, AUClast and AUCinf were within 80 - 125% acceptance range. CONCLUSION: In conclusion, Contiflo ICON 400 µg tablets developed by Ranbaxy Laboratories Limited is bioequivalent to the reference formulation in healthy adult male volunteers under fed condition.

Comparative bioavailability of two risperidone orodispersible tablet products after single dose administration.

OBJECTIVES: To compare the bioavailability of two risperidone orodispersible tablet products, Risperidone 1 mg Mouth dissolving tablet, Ranbaxy (Malaysia) Sdn. Bhd., Malaysia, as a test product and Risperdal 1 mg Quicklet, Janssen Ortho LLC, Gurabo, Puerto Rico, as a reference product, in healthy male volunteers under fasting condition. MATERIALS AND METHODS: A randomized, 2-treatment, 2-period, 2-sequence, single dose, crossover with a washout period of 2 weeks, was conducted in 24 healthy Thai male volunteers. Blood samples were collected at 0, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 5, 6, 8, 10, 12, 24, 36, 48, 72 and 96 h following drug administration. Plasma concentrations of risperidone and 9-hydroxyrisperidone were determined using a validated LC-MS-MS method. The pharmacokinetic parameters of risperidone and 9-hydroxyrisperidone were determined using a non-compartmental model. RESULTS: The geometric means ratios (%) and 90% confidence interval (CI) of the test and reference products for the log-transformed pharmacokinetic parameters, Cmax, AUC0-t and AUC0-inf of risperidone were 104.49 % (92.79% - 117.66%), 100.96 % (92.15% - 110.61 %) and 97.99 % (90.72% - 105.85%). The 90% CI of geometric means ratios of the test and reference products for the log-transformed pharmacokinetic parameters, Cmax, AUC0-t and AUC0-inf of 9-hydroxyrisperidone were 97.00%, 96.97% and 97.49%. CONCLUSIONS: The 90% CI for the geometric means ratios (test/reference) of the log-trasformed Cmax, AUC0-t and AUC0-inf of risperidone and its major active metabolite were within the bioequivalence acceptance criteria of 80% - 125% of the US-FDA.

Simple, economical, and reproducible LC-MS method for the determination of amoxicillin in human plasma and its application to a pharmacokinetic study.

A simple, economical, and reproducible high-performance liquid chromatography mass spectrometric (MS) method is developed and validated for the determination of amoxicillin in human plasma. The present method has been successfully used to determine bioequivalence between a test and innovator formulation of amoxicillin 500 mg capsules. The method is validated in terms of selectivity, precision/accuracy, recovery, dilution integrity, matrix effect, effect of anti-coagulant, and stability studies. Sample preparation is carried out by solid-phase extraction (HLB Oasis cartridges). The processed sample is chromatographed on Hypersil Gold (4.6 x 50 mm); 3 microm C18 column, using 10mM ammonium formate buffer (pH 5.0) and acetonitrile, (10:90, v/v) as mobile phase. Amoxicillin is detected by MS-MS detection with turbo-ion spray in positive ion mode. The weighed (1/X2) calibration curves were linear over the range of 0.17 to 17.0 microg/mL. The intra day precision is from 1.3% to 8.8% and intra day accuracy is 94.1% to 108.5%. The inter day precision is from 1.8% to 6.2% and inter-day accuracy is 95.1% to 105.9%. Mean recovery of 66.3% is observed for amoxicillin and 71.6% for internal standard (ampicillin). The stability of amoxicillin is studied at -15 degrees C and -50 degrees C using human plasma with different anti-coagulants (citrate, monobasic sodium phosphate, dextrose, and adenine-citrate, monobasic sodium phosphate, dextrose, and adenine and ethylene diamine tetraacetic acid-ethylene diamine tetraacetic acid). No significant degradation is observed for 60 days.

Influence of grape juice and orange juice on the pharmacokinetics and pharmacodynamics of diltiazem in healthy human male subjects.

OBJECTIVE: The objective was to study the effect of grape juice and orange juice on the pharmacokinetics (PK) and pharmacodynamics (PD) of diltiazem in healthy human volunteers. METHODOLOGY: The study design was open-label, balanced, randomized, 3-period, single-dose and crossover. A group of 12 healthy, adult, male human volunteers received a single oral dose of diltiazem 180 mg extended release capsule on three different occasions: with 200 ml of water, with 200 ml of grape juice and with 200 ml of orange juice in random order. A washout period of 7 days was kept between each study period. Serial blood samples were collected up to 24 h post dose and assayed for diltiazem using a specific and validated HPLC method. Blood pressure (BP) and ECG measurements were done at 0, 1, 2, 3, 4, 6, 8, 10, 12, 16 and 24 h post dose. Analysis of variance was carried out using logarithmic transformations of AUC and Cmax as well as nontransformed tmax. RESULTS: No significant change was observed in heart rate and BP. The median tmax was identical in all three occasions. The 90% CI of the Cmax ratios for orange juice/water were 104.59 - 114.86 and for grape juice/water were 93.91 - 103.13. Similarly, the 90% CI of the AUC0-inf ratios for orange juice and grape juice vs. water were 103.68 - 119.83 and 88.56 - 104.06, respectively. Since these values fall within the bioequivalence criteria of 80 - 120% limits, our study demonstrates absence of interaction of diltiazem with grape juice or orange juice. CONCLUSIONS: There is no significant influence of grape juice or orange juice on the pharmacokinetics and pharmacodynamics of diltiazem.

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.

Comparative bioavailability of two sertraline tablet formulations after single-dose administration in healthy Thai volunteers.

OBJECTIVE: To compare the bioavailability of two sertraline tablet (50 mg) formulations (Serlift from Ranbaxy Laboratories Ltd., Gurgaon Haryana, India, as a test formulation and Zoloft from Pfizer Australia Pty Ltd., West Ryde, New South Wales, Australia, as a reference formulation) in 24 healthy Thai male volunteers under fasting condition. MATERIALS AND METHODS: A randomized, 2-treatment, 2-period, 2-sequence, single-dose, crossover study with a washout period of 3 weeks, was conducted in 24 healthy Thai male volunteers. Blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 24, 36, 48, 72, 96 and 120 hours following drug administration. Plasma concentrations of sertraline were determined using validated LC-MS/MS method. Noncompartmental pharmacokinetics and statistical analyses were performed using SAS software for Windows, release 9.1 (SAS Institute Inc., Cary, NC, USA). RESULTS: The ratio of least square means and the 90% confidence intervals (CI) of the log-transformed data were 0.9950 (0.9111-1.0866) for Cmax, 1.0153 (0.9576-1.0764) for AUC(0-t) and 1.0110 (0.9510-1.0747) for AUC(0-infinity). In addition, the median tmax values for the test and reference formulations were similar (5.00 h). The 90% CI for Cmax, AUC(0-t) and AUC(0-infinity) were within the 0.8-1.25 interval of the US-FDA. CONCLUSIONS: The test formulation (Serlift, Ranbaxy Laboratories Ltd., Gurgaon, Haryana, India) is bioequivalent to the reference formulation (Zoloft, Pfizer Australia Pty Ltd., West Ryde, New South Wales, Australia) both in terms of rate and extent of absorption after single-dose administration under fasting condition.

A bioequivalence study comparing two formulations of lopinavir/ritonavir capsules.

This investigation was carried out to evaluate the bioavailability of a new single fixed-dose combination formulation of lopinavir and ritonavir, relative to reference product, Kaletra (133.3 mg lopinavir/33.3 mg ritonavir) capsules, manufactured by Abbott Laboratories, Chicago, IL, USA. The bioavailability study was carried out on 72 healthy male and female volunteers who received a single dose of 3 capsules (133.3 mg lopinavir/33.3 mg ritonavir) of the test (T) and the reference (R) products in the fasting state, in a randomized, balanced, 2-way crossover design. After dosing, serial blood samples were collected for a period of 72 hours. Plasma harvested from blood was analyzed for lopinavir and ritonavir by a sensitive and validated simultaneous liquid-chromatographic and mass-spectrometric (LC-MS/MS) assay. Mean oral clearance (Cl/F) values of the FDC were 4.92 and 23.54 l/h for lopinavir and ritonavir, respectively, the maximum plasma concentrations (C(max)), area under the plasma concentration-time curve up to the last measurable concentration (AUC(0-t)), and to infinity (AUC(0-infinity)), were analyzed statistically under the assumption of a multiplicative model. The time to maximum concentration (t(max)) was analyzed assuming an additive model. The parametric confidence intervals (90%) were calculated by Schuirmann's two 1-sided t-test criteria. It was found that the test/reference (T/R) ratios for the pharmacokinetic parameters AUC(0-t), AUC(0-infinity) and C(max) (after initial log transformation) were well within the bioequivalence acceptance range of 80-125% as per international regulatory guidelines. Therefore, the two formulations were considered to be bioequivalent [Food and Drug Administration 2003].

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.

Comparative bioavailability/bioequivalence of two different stavudine 40 mg capsule formulations: a randomized, 2-way, crossover study in healthy volunteers under fasting condition.

PURPOSE: The aim of this study was to compare the single-dose oral bioavailability of two formulations of stavudine 40 mg capsules in healthy human subjects. METHODS: A bioequivalence study of two oral capsule formulations of 40 mg stavudine was carried out in 40 healthy volunteers following a single-dose, 2-sequence, crossover and randomized design. The two formulations were stavudine 40 mg capsules (Ranbaxy Laboratories Ltd., Haryana, India) as test and zerit 40 mg capsules (Bristol-Myers Squibb, Princeton, NJ, USA) as reference product. Test and reference capsules were administered to each subject in each period separated by a 3-day washout period. Serial blood samples were collected for a period of 10 h. Blood plasma was analyzed for stavudine using a sensitive, reproducible, accurate and validated LC-MS/MS method. Pharmacokinetic parameters, including AUC(0-t), AUC(0-inf), C(max), t(max), t(1/2) and lambda(z), were determined from plasma concentrations for both formulations. AUC(0-t), AUC(0-inf) and C(max) were tested for bioequivalence after log-transformation of data. RESULTS: The LC-MS/MS method, used to quantify stavudine in human plasma, was specific and sensitive for stavudine. Plasma concentration profiles of stavudine test and reference treatments were similar. Geometric mean ratios and 90% confidence intervals for C(max), AUC(0-t) and AUC(0-inf) for stavudine were 99.9 (93.9-106), 99.9 (98.4-101) and 99.8 (98.2-101), respectively. Untransformed results for the same parameters were consistent with the natural log-transformed data. CONCLUSION: The two stavudine 40 mg capsule formulations examined were bioequivalent and may be used interchangeably in medical practice.

The effect of four different types of diet on the bioavailability of loracarbef.

This randomized open-label single-dose crossover pharmacokinetic study was carried out to assess the effect of different diets on the bioavailability of loracarbef in 24 healthy male volunteers. A single dose of loracarbef in 200-mg tablet form was administered at 5 different times: after overnight fasting, after two vegetarian (high-fat and low-fat) diets, and following two non-vegetarian (high-fat and low-fat) diets. Serial blood samples were collected up to 10 h post-dose. Serum loracarbef concentrations were determined by a validated high performance liquid chromatographic (HPLC) method. Area under curve (AUC) values were significantly affected only by non-vegetarian diets; however the time to reach maximum serum concentration (Tmax) was prolonged and the maximum serum concentration (Cmax was decreased by all types of meals. The non-vegetarian diets affected the rate of absorption of loracarbef more than the vegetarian diets. The lowest decrease in Cmax was produced by the high-fat vegetarian diet, while the maximum was produced by the low-fat non-vegetarian diet. The results of this study indicate that while the rate of loracarbef absorption is significantly decreased by all diets, the extent of absorption is only reduced significantly by the non-vegetarian diets. The rate of elimination (k(el)) was not found to be significantly decreased by any of the diets. As compared to the high-fat non-vegetarian diet, the time beyond minimum inhibitory concentration (MIC90) concentration was significantly increased by the high-fat vegetarian diet. The implications of these findings for the large Indian vegetarian population are considerable.

Nevirapine/lamivudine/stavudine as a combined-formulation tablet: bioequivalence study compared with each component administered concurrently under fasting condition.

OBJECTIVE: The objective of the study was to compare the bioequivalence of a fixed-dose combination of a nevirapine 200 mg, lamivudine 150 mg and stavudine 30 mg combination tablet with application of the 3 medications, at the same dosage, concurrently as separate formulations, in healthy, adult subjects under fasting conditions. MATERIAL AND METHODS: An open-label, balanced, randomized, 2-treatment, 2-period, 2-sequence, single-dose, crossover bioavailability study was conducted in 40 subjects with 21-day washout period between each treatment. Blood samples were collected for 168 hours. Plasma concentrations of nevirapine, lamivudine and stavudine were determined using a validated LC-MS-MS method. Noncompartmental pharmacokinetics and statistical analyses were performed using SAS (SAS Institute Inc., Cary, NC, USA) software (SAS System under Windows, Version 8.02). RESULTS: The ratios of least-square means and the 90% confidence intervals of the log-transformed data were calculated for AUC(0-t), AUC(0-inf), and Cmax. The 90% confidence interval for least-square mean ratio between test and reference formulation for log-transformed parameters Cmax, AUC(0-t) and AUC(0-inf) were within the requirements of the 80-125% range. CONCLUSION: The test formulation (Ranbaxy Laboratories Ltd., Gurgaon, India) is bioequivalent to the reference formulations both in terms of rate and extent of absorption after single-dose administration under fasting condition.

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.

Comparative effect of different types of food on the bioavailability of cefaclor extended release tablet.

This randomized, six-treatment, six-period, six sequence, single dose, crossover pharmacokinetic study assessed the effect of different types of food on the bioavailability of 500-mg cefaclor extended release tablet in 23 healthy male volunteers. A single dose of cefaclor extended release 500-mg tablet was administered at six occasions: after overnight fasting, after two vegetarian (high-fat and low-fat), two non-vegetarian (high-fat and low-fat) and rice diets. Serial blood samples were collected up to 12 h after dose. Serum cefaclor concentrations were determined by a validated HPLC method. An almost equivalent increase in both Cmax and AUC was observed with both high-fat non-vegetarian and low-fat vegetarian breakfasts. However, when MIC90 values, a pharmacodynamic end-point were compared, the low-fat vegetarian diet fared better than the high-fat non-vegetarian diet. The results obtained favor low-fat vegetarian diet (breakfast) to be taken with cefaclor extended release tablet to achieve maximum benefit in terms of clinical efficacy.

The effect of four different types of food on the bioavailability of cefaclor.

This randomized, open-label, balanced, five-treatment, five-period, five-sequence, single-dose and crossover pharmacokinetic study assessed the effect of different types of food on the bioavailability of cefaclor in 18 healthy male volunteers. A single dose of cefaclor, 250-mg capsule was administered at five occasions: after overnight fasting, after two vegetarian (high-fat and low-fat) diets and two non-vegetarian (high-fat and low-fat) diets. Serial blood samples were collected upto 8 h post dose. Serum cefaclor concentrations were determined by a validated HPLC method. AUC values were not significantly affected by food intake, but the T(max) was prolonged and C(max) was decreased, depending on the type of meal. The non-vegetarian diets affected the rate of absorption of cefaclor more than the vegetarian diets. The least decrease in C(max) was produced by low-fat vegetarian diet, while the maximum decrease was produced by high-fat non-vegetarian diet. The results of this study indicate that while the rate of absorption of cefaclor is significantly decreased, the extent of absorption and the rate of elimination are not significantly decreased in the presence of food. As compared to high-fat non-vegetarian diet, the time above MIC50 concentration was significantly increased by low-fat vegetarian diet. The implications of these findings for the large vegetarian Indian population are considerable.