Comparative study on the bioequivalence of two different gabapentin formulations. A randomised, two-period, two-sequence, crossover clinical trial in healthy volunteers

The bioequivalence of two capsule formulations containing 400 mg gabapentin (CAS 60142-96-3) was assessed in 24 healthy volunteers in an open, randomised, crossover, 2 periods x 2 sequences, with a minimum washout period of 7 days, single-dose study. Plasma samples were obtained at fixed time points, over 48 h (baseline (pre-dose), +0.5 h, +1 h, +1.5, +2, +2.5, +3, +3.5, +4, +8, +5, +6, +8, +10, +12, +24, +36 and +48 h after administration) and gabapentin concentrations were determined by means of an HPLC-MS method (LLOQ 50.2 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUCtlast, AUCinf and Cmax) were determined from the gabapentin concentration data using non-compartmental analysis. The results showed that all 90 % confidence intervals (obtained by ANOVA) were all within the predefined ranges: 93.87-111.87 % for Cmax 94.04-108.21 % for AUCtlast and 94.23-108.29 % for AUCinf. Consequently, this bioequivalence study was well designed in order to conclude that the test formulation and reference formulation were bioequivalent in terms of rate and extent of absorption.     

Comparative pharmacokinetics of a single oral dose of two formulations of amlodipine. A randomized, single-blind, two-period, two-sequence, crossover study

Amlodipine, a long acting dihydropyridine calcium channel antagonist, is prescribed worldwide for the treatment of angina and hypertension. The objective of this study was to compare the pharmacokinetics and to establish bioequivalence of two formulations of amlodipine. The study was performed at the Clinical Pharmacology Unit, Hospital de Clínicas, Medical School of Buenos Aires University. This randomized, single blind, two-period, two-sequence, comparative crossover study was conducted in 24 Caucasian healthy volunteers. A single oral 10 mg dose of amlodipine besylate (CAS 111470-99-6) test formulation and reference formulation were administered to the volunteers separated by a 3-week washout period in a crossover manner. Blood samples for pharmacokinetic analysis were collected over a period of 144 h after drug administration. Amlodipine was measured in plasma samples using a validated HPLC method with LC-MS-MS detection. A non-compartmental method was used for pharmacokinetic analysis. Bioequivalence between test and reference amlodipine samples were demonstrated as the calculated 90% confidence interval for the corresponding ratios of log transformed pharmacokinetic parameters (AUC(t), AUC(infinity) and C(max)) fell within the 80-125% range, the predetermined criterion for pharmacokinetic equivalence.     

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.     

Comparative bioavailability/ bioequivalence of two different sertraline formulations: a randomised, 2-period x 2-sequence, crossover clinical trial in healthy volunteers

An open-label, randomised, crossover single dose study, using 2 periods x 2 sequences, with a minimum washout period of 4 weeks, was conducted in order to assess the comparative bioavailability of two formulations of sertraline hydrochloride (CAS 79617-96-2) 100 mg tablets. Plasma samples were obtained at intake (baseline) and at +1 h, +2 h, +3 h, +4 h, +5 h, +6 h, +7 h, +8 h, +9 h, +12 h, +24 h, +48 h, +72 h and +96 h post administration. Sertraline plasma concentrations were determined by high pressure liquid chromatography with tandem mass detection (HPLC-MS/MS) and the lower limit of quantification was set at 100.15 pg/mL. Pharmacokinetic parameters used for bioequivalence assessment (AUClast, AUCinf and Cmax) were determined by non-compartmental analysis. Classical 90 % confidence intervals (90CI) were calculated for the overall sample, and for males and females separately, and gender effects were investigated using an appropriate model. The results showed that overall classical 90CI were 84.55-100.32 % for Cmax 86.96-98.68 % for AUClast, and 86.79-98.93 for AUCinf, that is, they were all within the predefined ranges for bioequivalence acceptance. Separate gender analysis showed very similar results for males and females when analysed independently, and no gender effects were detected in bioequivalence analysis (p > 0.05). It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.     

Comparative bioavailability of two fluconazole capsule formulations in healthy volunteers

This work reports the bioavailability of two fluconazole (CAS 86386-73-4) capsule formulations in 24 healthy volunteers of both sexes who received a single oral dose (150 mg). The study was conducted using an open, randomized, two-period crossover design with two-week washout interval. Plasma samples were obtained up to 168 h after drug administration and fluconazole concentration were analyzed using electrospray tandem mass spectrometry coupled to liquid chromatography. The pharmacokinetic parameters obtained for fluconazole after the administration of each formulation included the area under the curve (AUC)(0-168 h), AUC(0-infinity), maximum concentration (Cmax), time to reach Cmax (Tmax), elimination constant (Ke) and half-life (T1/2). The 90% confidence interval for the geometric mean of the individual ratio test formulation/reference formulation were 97.18-108.60% for AUC0-168 h), 90.87-111.11% for AUC(0-infinity), 104.88-114.88% for Cmax 90.38-136.79% for Ke, 91.87-108.93% for T1/2 and (-)1.5-(-)0.10 for Tmax (for individual differences). Since for both Cmax or AUC the 90% CI are within the interval proposed by the Food and Drug Administration (FDA), the test formulation (Zoltrix) is bioequivalent to the reference formulation for both the rate and the extent of absorption after single dose administration.     

Bioequivalence study of two fluconazole capsule formulations in healthy volunteers

OBJECTIVE: To compare the bioavailability of a fluconazole 150 mg capsule formulation from Laboratório Teuto Brasileiro Ltd., Brazil (test formulation), and Zoltec 150 mg capsule from Laboratórios Pfizer Ltd., Brazil (reference formulation), in 24 volunteers of both sexes. MATERIAL AND METHODS: The study was conducted open with randomized 2-period crossover design and a 2-week washout period. Plasma samples were obtained over a 168-hour interval. Fluconazole concentrations were analyzed by combined reversed-phase liquid chromatography and tandem mass spectrometry (LC/MS/MS) with positive ion electrospray ionization using selected ion monitoring method. From the fluconazole plasma concentration vs. time curves the following pharmacokinetic parameters were obtained: AUC(last), AUC(0-inf) and C(max). RESULTS: Geometric mean of fluconazole/Zoltec 150 mg individual percent ratio was 102.6% for AUC(last), 102.2% for AUC(0-inf) and 109.4% for C(max). The 90% confidence intervals were 97.3-108.2%, 97.0-107.8%, and 103.1-116.0%, respectively. CONCLUSION: Since the 90% CI for both Cmax, AUC(last) and AUC(0-inf) were within the 80-125% interval proposed by the Food and Drug Administration, it was concluded that fluconazole 150 mg capsule was bioequivalent to Zoltec 150 mg, according to both the rate and extent of absorption.     

Comparative bioequivalence study of two isotretinoin soft gel capsule formulations in healthy male volunteers

OBJECTIVE: To assess the bioequivalence of 2 oral isotretinoin (20 mg) soft gel capsule formulations. The reference preparation was Roaccutan/Roche while the test preparation was A-Cnotren/Pharmaten, Athens, Greece. SUBJECTS, MATERIAL AND METHODS: The study was an open, randomized, 2-period, 2-sequence, 2-treatment crossover, involving 38 healthy male volunteer subjects. All volunteers completed the study. Isotretinoin plasma concentrations were measured by a fully validated HPLC method. Special care was taken through the collection and analysis of the samples due to instability of isotretinoin to light and temperature. Pharmacokinetic parameters used to assess bioequivalence were AUC(0-last), AUC(0-infinity) for the extent of absorption and Cmax and Tmax for the rate of absorption. Statistical evaluation of Cmax, AUC(0-last), AUC(0-infinity) was done after semi-logarithmic transformation by 2-way analysis of variance (ANOVA). Tmax values were tested using the distribution-free Hodges-Lehman interval. RESULTS: The parametric 90% confidence intervals for ratio T/R ranged from 95.20-103.20% (point estimate 99.10%) for AUC(0-last), 94.57-102.30% (point estimate 98.36%) for AUC(0-infinity) and 94.81-102.90% (point estimate 98.77%) for Cmax, respectively. Based on the results of Tmax, k(el) and t(1/2), too, there were no statistically significant differences. CONCLUSION: As a result, the 2 isotretinoin preparations in accordance with the European Union bioequivalence requirements, are equivalent with respect to rate and extent of absorption.     

Comparative bioavailability of two different diclofenac formulations in healthy volunteers

The aim of the study was to assess the bioequivalence of two different diclofenac (CAS 15307-86-5) formulations (diclofenac free acid suspension as test formulation and diclofenac resinate suspension, Cataflam, as reference formulation) in 24 healthy volunteers. After an overnight fast, the volunteers received a single oral dose (50 mg) of each formulation, following an open, randomized, two-period crossover design, with a fourteen-day washout interval between doses. Serum samples were obtained over a 24-h interval post-dosing, and were analysed for their diclofenac content by HPLC-UV. No adverse effect was reported for any of the formulations administered. Geometric mean test/reference individual ratios were: 92.8% for AUC(0-24 h), 93.2% for AUC(0-infinity), 117.2% for Cmax, 131.0% for Ke and 76.2% for T1/2. The variability of Cmax parameter expressed as CV was greater than 25%. Since the 90% CI for AUC(0-24 h) mean ratio were within the 80-125% interval proposed by the Food and Drug Administration, it can be concluded that diclofenac free acid formulation is bioequivalent to diclofenac resinate formulation for the extent of absorption. Since the European Community Agency accepts a 90% CI for Cmax of 70-143%, it can be concluded that diclofenac free acid formulation is bioequivalent to diclofenac resinate formulation for both the rate and the extent of absorption after single dose administration.     

Metronidazole immediate release formulations: a fasting randomized open-label crossover bioequivalence study in healthy volunteers

Metronidazole is a BCS (Biopharmaceutics Classification System) class 1 drug, traditionally considered the choice drug in the infections treatment caused by protozoa and anaerobic microorganisms. This study aimed to evaluate bioequivalence between 2 different marketed 250?mg metronidazole immediate release tablets. A randomized, open-label, 2×2 crossover study was performed in healthy Brazilian volunteers under fasting conditions with a 7-day washout period. The formulations were administered as single oral dose and blood was sampled over 48?h. Metronidazole plasma concentrations were determined by a liquid chromatography mass spectrometry (LC-MS/MS) method. The plasma concentration vs. time profile was generated for each volunteer and the pharmacokinetic parameters Cmax, Tmax, AUC0-t, AUC0-∞, ke, and t1/2 were calculated using a noncompartmental model. Bioequivalence between pharmaceutical formulations was determined by calculating 90% CIs (Confidence Intervall) for the ratios of Cmax, AUC0-t, and AUC0-∞ values for test and reference using log-transformed data. 22 healthy volunteers (11 men, 11 women; mean (SD) age, 28 (6.5) years [range, 21-45 years]; mean (SD) weight, 66 (9.3) kg [range, 51-81?kg]; mean (SD) height, 169 (6.5) cm [range, 156-186?cm]) were enrolled in and completed the study. The 90% CIs for Cmax (0.92-1.06), AUC0-t (0.97-1.02), and AUC0-∞ (0.97-1.03) values for the test and reference products fitted in the interval of 0.80-1.25 proposed by most regulatory agencies, including the Brazilian agency ANVISA. No clinically significant adverse effects were reported. After pharmacokinetics analysis, it concluded that test 250?mg metronidazole formulation is bioequivalent to the reference product according to the Brazilian agency requirements.     

Bioequivalence study of two capsule formulations of omeprazole in healthy volunteers

The study was conducted in order to assess the bioequivalence of two capsule formulations (test and reference) containing 20 mg of omeprazole (5-methoxy-2-[[4-methoxy-3,5-dimethyl-2-pyridinyl) methyl]sulfinyl]-1H-benzimidazole, CAS 73590-58-6). Fifty healthy male and female volunteers were treated in a single-centre, randomised, repeated-dose (once daily for six consecutive days), open-label, two-way crossover study, with a washout period of at least 9 days between treatments. Plasma samples were collected up to 12 h post-dosing for the determination of omeprazole by HPLC with photodiode array detector (DAD). The evaluation of bioequivalence was based on the following pharmacokinetic parameters that were calculated by standard non-compartmental methods: area under the plasma concentration-time curve from zero to the time of the last quantifiable concentration (AUCt) and that extrapolated to infinity (AUC) and the maximumobserved concentration (Cmax). The 90% confidence interval around the ratios (test/reference) (obtained by analysis of variance, ANOVA) were 0.92-1.04 forCmax, 0.88-1.05 for AUCt, and 0.88-1.05 for AUC, i.e., within the predefined acceptable range for the conclusion of bioequivalence. The study indicated that the test and reference formulations containing 20 mg of omeprazole are bioequivalent in terms of both the rate and extent of bioavailability.     

Bioequivalence study of two fluoxetine capsule formulations in healthy Middle Eastern volunteers

OBJECTIVE: To assess the bioequivalence of two fluoxetine hydrochloride capsule (20 mg) formulations (Fluoxicare capsule from Pharmacare Ltd., Chemicals and Cosmetics, Ramallah, Palestine, as test formulation, and Prozac from Eli Lilly Ltd., Basingstoke, UK, as reference formulation). DESIGN AND METHODS: The study was conducted open with a randomized 2-period crossover design and a 6-week washout period. Participants were 24 healthy male volunteers aged 18-28 years, divided into 2 groups of 12 subjects. One group was given the originator drug (reference formulation), and the other was given the test formulation. Blood samples were obtained at baseline and at 14 time points during the interval 0-96 hours after drug administration. The concentrations of the samples were assayed spectrophotometrically at 220 nm using a Shimadzu 160 A UV-visible spectrometer. We calculated the plasma concentration-time curve (AUC), maximum plasma concentration (Cmax), and time of maximum plasma concentration (tmax) for each subject. Logarithmic transformation of the AUC and Cmax was used for the statistical analyses and to assess the bioavailability of the two formulations, using analyses of variance (ANOVA) and Satherwait t-tests for unequal variances. The ANOVA performed of tmax in Cmax, and in AUC provided the appropriate intra-subject variance estimates to evaluate the 90% confidence intervals for the differences between study variables after administration of the test and reference formulations. Statistical analyses were conducted on AUC 0-4 as the extrapolated part of the AUC, a truncated area approach was adapted. RESULTS: The mean pharmacokinetic parameters for both of the drugs under study were as follows: Cmax = 61.24 (+/- 12.96) ng/ml for the test formulation, and for the reference formulation Cmax = 61.39 (+/- 14.1) ng/ml, the effects were statistically equivalent. The tmax for the test formulation was 8.25 (+/- 1.7) and 7.33 (+/- 0.96) for the reference formulation. The area under the curve to infinity (AUC 0-infinity (ng, day/ml)) for the test formulation and for the reference formulation were 293.02 (+/- 52.69) and 296.15 (+/- 61.69), respectively. CONCLUSIONS: The two formulations had equivalent pharmacokinetic parameters, were well-tolerated, and their relative bioavailability was 98.94%.     

Bioequivalence study of two letrozole tablet formulations. Single dose, randomized, open-label, two-way crossover bioequivalence study of letrozole 2.5 mg tablets in healthy volunteers under fasting conditions

The study was conducted in order to compare the bioavailability of two tablet formulations containing letrozole 2.5 mg (CAS 112809-51-5). Twenty healthy subjects were enrolled in a single-centre, bioequivalence, randomised, single-dose, open-label, two-way crossover study, performed under fasting conditions with a minimum washout period of 21 days. Plasma samples were collected up to 240 h post-dosing. Letrozole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection, LC/MS/MS method. Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(0-t)) and from time zero to infinitive (AUC(0-inf)) and maximum observed concentration (Cmax), were determined from the letrozole concentration data using non-compartmental analysis. The 90% confidence intervals obtained by analysis of variance were 90% geometric confidence Intervals of the ratio (A/B) of least-squares means from the analysis of variance (ANOVA) of the In-transformed AUC(0-t), and Cmax was within 80% to 125%. Bloequivalence between formulations was concluded both in terms of rate and extent of absorption.     

Bioequivalence study of two formulations of itraconazole 100 mg capsules in healthy volunteers under fed conditions: a randomized,three-period,reference-replicated,crossover study

Background: The aim of the study was to evaluate the bioequivalence of two itraconazole 100 mg capsule formulations.

Research design and methods: The single-center, open-label, randomized, three-period, three-sequence, reference-replicated, cross-over study included 38 healthy subjects under fed conditions. In each study period (separated by a 14-day washout), a single oral dose of the test (T) or reference (R) product was administered. Blood samples were collected at pre-dose and up to 72.0 h after administration. The calculated pharmacokinetic parameters, based on the plasma concentrations of itraconazole and hydroxy itraconazole, were AUC_0-72h, AUC_0-∝, C_max, T_max, T_1/2 and K_el.

Results: The 90% CI for the test/reference geometric means ratio for the parent compound, itraconazole, was in the range from 85.29% to 116.07% for AUC_0-72h. Since the coefficient of variation (CV) for the reference product was 44.95% for C_max, the 90% CI for this parameter for itraconazole was 93.49–133.78%, which was within the proposed limits of the EMA for bioequivalence of 72.15–138.59%. During the study, 4 subjects encountered a total of 14 mild adverse events.

Conclusions: The use of the reference-scaling approach with 3-period design (TRR, RTR, and RRT) was an efficient way to demonstrate that two commercially available oral itraconazole formulations met the predetermined bioequivalence criteria.     

Comparative bioavailability of two capsule formulations of ofloxacin in healthy volunteers after a single dose administration

Abstract

The bioavailability of two ofloxacin (OFX) tablet formulations (OTT, test formulation from Laboratorio Atral SA - Portugal, and Tarivid, reference formulation from Hoechst AG - Germany) were compared in 24 (12M, 12F) healthy volunteers who received a single oral dose of 200 mg of each formulation in an open, randomized, two-period crossover fashion with a 14 day washout interval between doses. Plasma samples were obtained over a 24 h interval and OFX concentrations were determined by HPLC with UV detection. From the OFX plasma concentration vs time curves, the AUC_[0-24] (area under the concentration vs time curves from 0 to 24 h), AUC_[0-α] (area under the concentration vs time curves extrapolated to infinity), C_max (maximum concentration achieved), t_max (time to achieve C_max), t_1/2 (terminal first order elimination half-life), and elimination constant (K_e) were obtained. All these variables were analyzed using both parametric and non-parametric statistics. The two OFX tablet brands did not show statistically significant differences in bioavailability as assessed by the statistical analysis of AUC_[0-24] (14.8 and 14.7μg h ml^?1, respectively for OTT and Tarivid), AUC_[0-α] (16.0 and 15.6 μg h ml^?1), C_max (2.9 and 3.1 μg/ml), t_max (0.8 and 1.5 h), t_1/2 (5.9 and 5.6 h), and K_e (0.12 and 0.13 h^?1) values. Based on these results and on the United States Food and Drug Administration (FDA) requirements [1993], both formulations were considered to be bioequivalent.     

Comparative pharmacokinetics and pharmacodynamics of two marketed bid formulations of diltiazem in healthy volunteers

Cardizem®SR and Bi-Tildiem® were both approved in their respective countries on the basis of clinical trials demonstrating efficacy and safety in the treatment of angina pectoris. In this cross-over randomized study, we assessed whether these two sustained-release formulations of diltiazem have equivalent pharmacokinetic and pharmacodynamic profiles. Twenty-four young healthy male volunteers were hooked to Holters and ambulatory blood pressure monitors for 24 h to establish baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), sinus rate and PR intervals. They then received a single dose of 120 mg of diltiazem from one formulation. The pharmacodynamic measurements were recorded for a further 24 h and blood samples were collected over 36 h for evaluation of diltiazem in plasma by a high-performance liquid chromatographic (HPLC) method. The procedures were repeated with the alternate formulation after a 7 d wash-out. Pharmacokinetics showed statistically significant (p <0.01) differences in AUC_0–12 with means (±SD) of 519.2(±172.8) and 429.6(±147.2)ng h ml^?1, AUC_0–36 of 835.6(±281.6) and 730.9 (±271.5)ng h ml^?1 and C_max of 89.1(±30.3) and 61.1(±21.2) ng ml^?1 for Cardizem®SR and Bi-Tildiem®, respectively. The only pharmacodynamic parameter showing a statistically significant difference in change from baseline between the two formulations was DBP with mean (±SD) change in AUC_0–12 of ?13.6(±20.8) and +8.4(±31.7) mm Hg h (p = 0.0135) and in AUC_0–24 of ?33.0(±43.7) and ?0.3(±59.2) mm Hg h (p = 0.0463) for Cardizem®SR and Bi-Tildiem®, respectively. These findings suggest that assessment of efficacy of sustainedrelease formulations of diltiazem by bioequivalence could be misleading. They also confirm that a single dose of diltiazem does not elicit a significant pharmacodynamic response in healthy volunteers. Equivalence for such formulations should therefore be demonstrated by pharmacodynamic evaluation or clinical studies in a patient population.     

Comparative study on the bioequivalence of two formulations of pravastatin. Data from a crossover, randomised, open-label bioequivalence study in healthy volunteers

An open-label, randomised, crossover single-dose study, using two periods, two sequences, with a minimum washout period of 7 days, was conducted in order to assess the comparative bioavailability of a pravastatin (CAS 81131-70-6) 40 mg formulation and that of a reference formulation. Blood samples were collected up to +14 h post dosing, the plasma was separated and pravastatin concentrations were determined by high-performance liquid chromatographic method with tandem mass spectrometry detection (HPLC-MS/MS), with a lower limit of quantification of 0.40 ng/mL. Bioequivalence analyses were conducted using two models. The main analysis was done according to a general linear model (model I) using formulation, period and sequence as fixed model effects, and subject(sequence) and residual as random effects; gender-related differences were investigated using ANOVA (model II), including formulation, period, sequence, gender, sequence-by-gender interaction and gender-by-formulation interaction as fixed model effects and subject within sequence-by-gender interaction and residual as random effect. Mean values of the individual Cmax were 126.73 +/- 61.99 ng/mL and 123.52 +/- 52.78 ng/mL for the test and reference, spectively. Mean +/- SD total area under the curve up to the last measurable concentration (AUClast) was 224.26 +/- 104.74 ng x h/mL for the test formulation and 216.55 +/- 80.30 ng x h/mL for the reference formulation. Mean +/- SD total area under the curve (AUCinf) was 226.72 +/- 104.69 ng x h/mL for the test formulation and 218.81 +/- 79.95 ng x h/mL for the reference. Terminal elimination half-life was 2.15 +/- 0.85 h for test and 1.97 +/- 0.54 h for the reference. Ninety percent confidence intervals were comprised within the bioequivalence acceptance criteria (80-125 %) for all of the parameters analysed, both using model I and model II. Model II returned a statistically significant gender effect (p < 0.05) for Cmax, AUClast and AUCinf but the effect became non-significant (p > 0.05) when the dose was adjusted per body weight for all three parameters. The comparison between male and female mean body weight showed a significant difference: p = 0.03, 95 % confidence intervals 68.27-76.93 kg (men), 56.84-60.61 kg (women). These results suggest that the effect of gender in the bioequivalence analysis in model I could be due to a difference in body weight between males and females. Both formulations were shown to be bioequivalent in terms of rate and extent of absorption, irrespectively of the model used.     

Comparative bioavailability study with two chlorpropamide tablet formulations in healthy volunteers

OBJECTIVE: The aim of this study was the assessment of the bioequivalence of two formulations (250 mg tablet) of chlorpropamide (CAS 94-20-2) in 36 healthy volunteers of both sexes. METHODS: The study was conducted using an open, randomized, two-period crossover design with a 3-week washout interval. Plasma samples were obtained over a 72-h period. Plasma chlorpropamide concentrations were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS-MS) with positive ion electrospray ionization using multiple reaction monitoring (MRM). From the chlorpropamide plasma concentration vs time curves, the following pharmacokinetic parameters were obtained: AUC(0-72h), AUC(inf) and C(max). RESULTS: The limit of quantification was 0.1 microg/mL for plasma chlorpropamide analysis. The geometric mean and respective 90 % confidence interval (CI) of Test/ Reference percent ratios were 93.99% (87.11%-101.41%) for C(max), 92.45% (85.96%-99.44%) for AUC(0-72h) and 90.30% (83.35%-97.82%) for AUC(0-inf). CONCLUSION: Since the 90 % CI for AUC(0-72h), AUC(0-inf) and C(max) ratios were within the 80-125%interval proposed by the US FDA, it was concluded that chlorpropamide 250 mg tablet (test formulation) was bioequivalent to the reference 250 mg tablet for of both the rate and extent of absorption.