Comparative bioavailability of two immediate-release tablets of lisinopril/hydrochlorothiazide in healthy volunteers

AIM: Two formulations of lisinopril/hydrochlorothiazide (20 mg/12.5 mg) were evaluated for bioequivalence after single dosing in healthy volunteers. METHODS: The study was conducted according to an open, randomized, 2-period crossover design with a 2-week washout interval between doses. Twenty-four volunteers participated and all completed the study successfully. Lisinopril and hydrochlorothiazide were determined in plasma by HPLC. The pharmacokinetic parameters AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were tested for bioequivalence after logarithmic transformation of data and ratios of tmax were evaluated non-parametrically. RESULTS: For lisinopril, the parametric analysis revealed the following test/reference ratios and their confidence intervals (90% CI): 1.01 (0.84-1.22) for AUC(0-t), 0.98 (0.81-1.19) for AUC(0-infinity), 1.02 (0.83-1.25) for Cmax and 1.03 (0.99-1.08) for Cmax/AUC(0-infinity). The 90% CI for tmax was 0.94-1.07. All parameters showed bioequivalence between both formulations. As for hydrochlorothiazide, test/reference ratios and their confidence intervals (90% CI) were: 1.05 (0.95-1.17), 1.02 (0.93-1.12) for AUC(0-infinity), 0.99 (0.89-1.07) for Cmax and 0.97 (0.90-1.04) for Cmax/AUC(0-infinity). The 90% CI for tmax was 1.00-1.41. All parameters showed bioequivalence between both formulations except for tmax. A discrete fall in both systolic (SBP) and diastolic (DBP) blood pressure was observed after drug administration. The time course of both parameters was similar for the 2 formulations. Heart rates also followed a similar time profile. CONCLUSIONS: The bioequivalence of the 2 formulations of lisinopril/hydrochlorothiazide was demonstrated.     

Bioequivalence study of two oral formulations of cefadroxil in healthy volunteers

Two different cefadroxil (CAS 50370-12-2) formulations were evaluated for their relative bioavailability in 24 healthy volunteers who received a single 500 mg oral dose of each preparation. An open, randomized clinical trial designed as a two-period crossover study with a 7-day washout period between doses was employed. Plasma samples for assessments of their cefadroxil concentration by HPLC-UV were obtained over 8 h after administration. Values of 48.94 +/- 10.18 pg x h/ml for test, and 48.51 +/- 9.02 microg x h/ml for the reference preparation AUC(0-t) demonstrate a nearly identical extend of drug absorption. Maximum plasma concentration Cmax of 16.04 +/- 4.94 microg/ml and 16.01 + 4.02 microg/ml achieved for the test and reference preparations did not differ significantly. The parametric 90% confidence intervals (CI) of the mean of the difference (test-reference) between log-transformed values of the two formulations were 96.80% to 104.51% and 92.01% to 107.00% for AUC(0-t) and Cmax, respectively. Since for both AUC(0-t) or Cmax the 90% CI values are within the interval proposed by the Food and Drug Administration, the test product is bioequivalent to the reference product for both the rate and extent of absorption after single dose administration.     

Bioequivalence evaluation of cefdinir in healthy fasting subjects

A simple and sensitive HPLC method was developed to determine cefdinir (CAS 91832-40-5) in human plasma. The method was validated by investigating the accuracy and precision for intra- and inter-day runs in a linear concentration from 0.05-2.0?μg/ml. The object of this study was to compare the bioavailability of cefdinir capsule (reference) and cefdinir granule (test) containing 100?mg of cefdinir. A randomized, open-label, single-dose, 2-way crossover bioequivalence study in 20 healthy, Chinese, male subjects was conducted. A 1-week wash-out period was applied. Blood samples were collected before and with 10?h after drug administration. The formulations were compared using the following pharmacokinetic parameters: AUC0-t, AUC0-∞ and C max. The 90% confidence interval (CI) of the ratios of log-transformed AUC0-t and AUC0-∞ were used to assess bioequivalence between the 2 formulations using the equivalence interval of 80 and 125%. The results showed that the 90% CI of the ratios of AUC0-t, AUC0-∞ and C max were 102.5% (94.7-111.0%), 103.4% (94.8-112.7%) and 106.4% (97.0-116.7%), respectively, which indicated 2 formulations of cefidinir are bioequivalent. Both treatments showed similar tolerability and safety.     

In vitro and in vivo equivalence of two oral atenolol tablet formulations

A randomised, cross-over, open study of bioequivalence between two different atenolol (CAS 29122-68-7) tablet formulations is presented. An in vitro comparative study between the two formulations was also performed. Both products meet the USP 23 (United States Pharmacopea) specification. The values of similarity factor (f2) and difference factor (f1) obtained ensure sameness or equivalence of the two dissolution curves. Twenty-four healthy volunteers (male/female) participated in the bioequivalence study. Each treatment was given as a single 100-mg tablet following an overnight fast. Atenolol concentrations in plasma were determined up to 30 h after treatment by HPLC. The pharmacokinetic parameters AUC0-infinity, Cmax and Cmax/AUC0-infinity were tested for bioequivalence after logarithmic transformation of data and ratios of tmax were evaluated nonparametrically. The parametric analysis revealed the following test/reference ratios and their 90% confidence intervals (90% CI): 1.06 (0.99-1.13) for AUC, 1.07 (0.97-1.18) for Cmax, and 0.99 (0.94-1.07) for Cmax/AUC0-infinity. The 90% CI for tmax was 0.91-1.23. All parameters showed bioequivalence between both formulations. A discrete fall in both systolic (SBP) and diastolic (DBP) blood pressure was observed after the drug administration. The fall extent (approximately 11 mmHg in supine position) and the time course of both parameters after the drug administration was similar for both formulations. Minimal values for SBP and DBP were achieved at 6 h after the drug administration for both formulations. Heart rates were also reduced after the administration of both formulations of atenolol in a similar extent (12 b.p.m.) and following a similar time profile (i.e. maximal reductions were observed between 1 and 3 h after the drug administration). It can be concluded that both formulations are equivalent in vitro and in vivo.     

In vivo pharmacokinetic-pharmacodynamic relationship and in vitro equivalence of two oral furosemide tablet formulations

A randomized, cross-over, open study of bioequivalence between two different furosemide (CAS 54-31-9) formulations was performed; simultaneously, diuretic effects (urine output, sodium, potassium and chloride excretion) were also compared. Both products meet the British Pharmacopoeia specification and the results of a previous in vitro comparative study ensure equivalence of the two dissolution curves. Twenty-four healthy volunteers (male/female) participated in the bioequivalence study. Each treatment was given as a single 40-mg tablet following an overnight fast. Furosemide concentrations in plasma (measured by HPLC) and electrolyte amounts in urine were determined up to 12 h after treatment. The pharmacokinetic parameters AUC0-infinity, Cmax and Cmax/AUC0-infinity were tested for bioequivalence after ln-transformation of data and ratios of tmax were evaluated nonparametrically. The parametric analysis revealed the following test/reference ratios and their 90% confidence intervals (90% CI): 1.06 (0.94-1.19) for AUC0-infinity, 1.12 (0.96-1.31) for Cmax, and 1.06 (0.97-1.16) for Cmax/AUC0-infinity. The 90% CI for tmax was 0.55-1.00. Bioequivalence between both formulations was concluded for all parameters except for tmax. No significant diuretic differences between both formulations (test and reference) were observed after drug administration in relation to the baseline period. Systolic and diastolic blood pressure and heart rate showed a similar time-course after the drug administration and there were no differences between both formulations. Both products were well tolerated. It can be concluded that both formulations are equivalent in vitro and in vivo.     

Bioequivalence of two oral ciprofloxacin tablets formulations

The relative bioavailability of a new 750 mg tablet formulation of ciprofloxacin (test formulation supplied by Dr. August Wolff GmbH and Co., Germany) was compared with that of Ciprobay tablets 750 mg (reference formulation from Bayer Vital GmbH and Co., Germany). Twenty-four healthy volunteers (12 male and 12 female) were included in this single-dose, 2-sequence, crossover randomized study. Blood samples were obtained prior to dosing and at 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 18, 24 and 30 hours after drug administration. Plasma concentrations of ciprofloxacin were determined by HPLC. No differences were found when the in vitro dissolution profiles of both formulations were compared. The pharmacokinetic parameters AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were tested for bioequivalence after log-transformation of data, and ratios of tmax were evaluated nonparametrically. The parametric analysis revealed the following mean values for the test/reference ratios (90% standard confidence intervals in parenthesis (ln-transformed data): 1.01 (0.95-1.07) for AUC(0-t), 0.99 (0.93-1.05) for AUC(0-infinity), 1.05 (0.97-1.14) for Cmax and 1.06 (0.97-1.15) for Cmax/AUC(0-infinity). The nonparametric confidence interval for tmax was 0.77-1.15. All parameters showed bioequivalence between both formulations as their confidence intervals were within the bioequivalence acceptable range of 0.80-1.25 limits; the 90% confidence interval for tmax slightly exceeded limits of bioequivalence. We conclude that both formulations show bioequivalence for both the rate and the extent of absorption.     

Bioequivalence study of two limaprost alfadex 5 microg tablets in healthy subjects: moisture-resistant tablet (dextran formulation) versus standard tablet (lactose formulation)

OBJECTIVE: A study was conducted to assess the bioequivalence of two limaprost alfadex 5 microg tablets, a moisture-resistant tablet (dextran formulation) and a standard tablet (lactose formulation). MATERIALS AND METHODS: The clinical investigation was designed as a randomized, open-labeled, two-part, two-treatment, two-period crossover study, in 120 healthy male volunteers. One tablet of either formulation was administered with 200 ml of water after 10-hour overnight fast. After dosing, serial blood samples were collected for a period of 6 hours. Plasma harvested from blood was analyzed for limaprost by a validated LC/MS/MS method. The peak plasma concentration (Cmax) values and time associated with the maximal concentration (tmax) were obtained from the observed data. The elimination rate constant (lambda z) was obtained as the slope of the linear regression of the log-transformed concentration values vs. time data in the terminal phase, and the elimination half-life (t1/2) was calculated as 0.693/lambda z. The area under the curve to the last measurable point (AUC0-t) was estimated by the linear trapezoidal rule. The analysis of variance (ANOVA) was carried out using log-transformed AUC0-t, AUC0-A yen and Cmax and untransformed tmax, and 90% confidence intervals for AUC0-t and Cmax were calculated. If the 90% confidence intervals (CI) for both AUC0-t and Cmax fell fully within the interval 80 - 125%, the bioequivalence of the two formulations was established. RESULTS: The means of AUC0-t were 0.779 vs. 0.754 pg x h/ml (test vs. reference), and the means of the Cmax were 1.26 vs. 1.12 pg/ml (test vs. reference). The geometric mean ratios of the test formulation to reference formulation for AUC0-t and Cmax were 104.0 and 112.4%, respectively, and the 90% CI for AUC0-t and Cmax were 100.7 - 107.4% and 105.6 - 119.6%, respectively. Both 90% CI for AUC0-t and Cmax fell within the Ministry of Health, Labour and Welfare of Japan accepted bioequivalence range of 80 - 125%. CONCLUSIONS: Based on the results, the moisture-resistant tablet was determined to be bioequivalent to the standard tablet.     

Bioavailability study of two oral formulations of didanosine in healthy volunteers

An open-label, randomised, crossover single dose study, using 2 periods, 2 sequences, with a minimum washout period of 7 days, was conducted in order to assess the comparative bioavailability of two formulations of didanosine (CAS 69655-05-6) 100 mg tablets. Didanosine plasma concentrations were determined by means of a validated HPLC method [DAD detector, stavudine (CAS 3056-17-5) as an internal standard]. The limit of detection was 30 ng/ml. The results showed that overall classical 90 % confidence intervals (CI) were 92.4-111.2 % for AUC0-inf, 91.8-109.9 %f for AUC0-t, and 87.0-110.0 % for Cmax. Since the 90 % CI for both, AUC and Cmax ratios were within the 80-125 % interval proposed by the European Agency for the Evalution of Medicinal Products (EMEA) and Food and Drug Administration (FDA), it is concluded that the new didanosine formulation is equivalent to the conventional formulation for both, the extent and the rate of absorption after single dose administration in healthy volunteers.     

Bioequivalence of Lamotrigine 50-mg Tablets in Healthy Male Volunteers: a Randomized, Single-Dose, 2-Period, 2-Sequence Crossover Study

To compare the bioavailability of two 50-mg lamotrigine dispersible tablet formulations (Epilepax?, Ivax-TEVA Argentina Laboratories, Argentina, as a test formulation, and Lamictal?, GlaxoSmithKline, UK, as a reference formulation) in 24 healthy male volunteers.This study was a randomized, 2-period, 2-sequence crossover design that was open for subjects and investigators, but blind for the bioanalytical lab. Serum samples were obtained over a 120-h interval. A 9-day wash-out period was allowed between treatments. The concentrations of lamotrigine were analyzed by high-performance liquid chromatography followed by ultraviolet-visible detection. Lamotrigine time-concentrations curves were obtained and the following pharmacokinetic parameters were calculated: AUC0-t, AUC0-inf and Cmax. Bioequivalence was declared if the 90% confidence interval (CI) of the mean test/reference ratios for AUC0-t, AUC0-inf and Cmax were within 80.00-125.00%.The geometric mean and respective 90% CI of test/reference percent ratios were 100.83% (92.53-107.88%) for AUC0-t, 99.91% (93.79-108.40%) for AUC0-inf, and 95.62% (90.91-100.57%) for Cmax. No serious adverse events were observed. 1 patient reported a mild rash following the administration of each formulation.This single dose study found that the test and reference products met the regulatory criteria for bioequivalence in this sample of fasting healthy volunteers. These results suggest that bioequivalence studies evaluating 50-mg doses of Lamotrigine are feasible and recommended, since such doses may minimize the risk of severe rash or Stevens-Johnson Syndrome. This study was registered at the Argentinean Clinical Trials National Registry (www.anmat.gov.ar), No 1666/2008.     

Comparative bioavailability study of two preparations of letrozole in healthy subjects

The bioavailability of a new letrozole (CAS 112809-51-5) preparation was compared with the reference preparation of the drug in 25 healthy volunteers, aged between 18 and 33. A single dose of 2.5 mg was given orally in the fasted state, using a randomized two-way, cross-over protocol. A washout period of two weeks separated both treatment periods. Blood samples were obtained at regular time intervals, until 312 h after drug administration. After solid phase extraction (SPE) letrozole plasma levels were measured by high pressure liquid chromatography that was validated before the start of the study (UV detector, fluoroletrozole as an internal standard). The limit of quantification was 1.4 nmol/ml. The following pharmacokinetics parameters were calculated from letrozole plasma concentrations: AUC(0-infinity), AUC(0-t), Cmax, tmax, F(rel), MRT, t(1/2), k(el). The confidence intervals for the statistical calculations of AUC(0-infinity), Cmax, tmax were 95 % and AUC(0-t), MRT, t(1/2), k(el) were tested by means of the unpaired t-tests procedure and after logarithmic transformation for overall significant differences using analysis of variance--three-way ANOVA. The AUC(0-infinity) ratio test/reference and the 90 % confidence interval were 99.52 %, and 94.05-107.31%, respectively. The Cmax ratio test/reference and the 90 % confidence interval were 89.18 %, and 84.48-98.60%, respectively. AUC(0-infinity) and Cmax ratios (90 % CI) were within the 80-125 % interval required for bioequivalence as stipulated in the current international regulations of the European Agency for the Evalution of Medicinal Products and the Food and Drug Administration. Therefore it is concluded that the new letrozole preparation is therapeutically equivalent to the reference preparation for both the extent and the rate of absorption after single dose administration in healthy volunteers.     

Comparative bioavailability of two oral formulations of bromazepam in healthy volunteers.

The aim of this study was to assess the pharmacokinetic profile of two bromazepam (CAS 1812-30-2) formulations in 24 healthy volunteers. An open, randomised clinical trial designed as two-period crossover with 14-day washout between doses was employed. Plasma samples for assessments of their bromazepam concentration by HPLC-UV were obtained over 96 h after administration. No adverse effect was reported for any of the formulations administered. The following pharmacokinetics parameters were calculated: AUC(0-96 h), AUCinf, Cmax, Tmax, Ke and T1/2. The 90% confidence intervals (CI) for the mean test/reference individual ratios were 81-109 for AUC and 84-116 for Cmax. Since the 90% CI for both, AUC and Cmax ratios were within the 80-125% interval proposed by the Food and Drug Administration, it is concluded that the new bromazepam slow-release formulation is therapeutic equivalent to the conventional formulation for both, the extent and the rate of absorption after single dose administration in healthy volunteers.     

Comparison of two microemulsion of cyclosporine A in healthy volunteers

This study evaluated the bioequivalence of a new Cyclosporine A microemulsion formulation in comparison to the reference market standard. Twenty-four adult healthy volunteers were randomised to receive the two Cyclosporin A microemulsion formulations, at a dose of 2.5 mg/kg, according to a cross-over design. Blood samples were taken before drug administration and at 12 points within 24 hours. Cyclosporine A whole blood concentrations were determined by HPLC. The pharmacokinetic parameters AUC0-t and AUC0-infinity were calculated by the trapezoidal rule, Cmax and Tmax were obtained directly from blood data. AUCs and Cmax were tested for bioequivalence after log transformation of data, differences for Tmax were evaluated by the rank test of Wilcoxon for paired data. The 90% confidence interval ratio between tested/reference drug was 0.98 for AUC0-t, 0.96 for AUC0-infinity and 1.01 for Cmax. All of them were within the range of bioequivalence. Tmax was 1.60 +/- 0.44 hours after test drug and 1.67 +/- 0.48 after reference drug (p = 0.27, Wilcoxon test). According to these results the two Cyclosporine A microemulsion formulations can be considered bioequivalent.     

Comparative bioavailability study of doxycycline hyclate (equivalent to 100 mg doxycycline) capsules (doxycin vs vibramycin) for bioequivalence evaluation in healthy adult volunteers

This investigation was carried out to evaluate the bioavailability of a new capsule formulation of doxycycline (100 mg), doxycin, relative to the reference product, vibramycin (100 mg) capsules. The bioavailability was carried out in 24 healthy male volunteers who received a single dose (100 mg) of the test (A) and the reference (B) products after an overnight fast of at least 10 hours on 2 treatment days. The treatment periods were separated by a 2-week washout period. A randomized, balanced 2-way cross-over design was used. After dosing, serial blood samples were collected for a period of 48 hours. Plasma concentrations of doxycycline were analyzed by a sensitive and validated high-performance liquid chromatography assay. The pharmacokinetic parameters for doxycycline were determined using standard noncompartmental methods. The parameters AUC(0-t), AUC(0-infinity), Cmax, K(el), t(1/2) and Cmax/AUC(0-infinity) were analyzed statistically using log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pharmacokinetic parameters: AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were within the range 80-125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis of the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were 95.98-109.56%, 92.21 to 107.66%, 93.90-112.56%, and 96.0 to 106.91% respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) by the Schuirmann's two 1-sided t-tests. Therefore, the 2 formulations were considered to be bioequivalent.     

Comparative bioavailability study of cefixime (equivalent to 100 mg/5 ml) suspension (Winex vs Suprax) in healthy male volunteers

This investigation was carried out to evaluate the bioavailability of a new suspension formulation of cefixime (100 mg/5 ml), Winex, relative to the reference product, Suprax (100 mg/5 ml) suspension. The bio-availability study was carried out in 24 healthy male volunteers who received a single oral dose (200 mg) of the test (A) and the reference (B) products on 2 treatment days after an overnight fast of at least 10 hours. The treatment periods were separated by a one-week washout period. A randomized, balanced two-way crossover design was used. After dosing, serial blood samples were collected over a period of 16 hours. Plasma concentrations of cefixime were analyzed using a sensitive high-performance liquid chromatographic assay. The pharmacokinetic parameters for cefixime were determined using standard non-compartmental method. The parameters AUC(0-t), AUC(0-infinity), Cmax, Kel, t1/2 and Cmax/AUC(0-infinity) were analyzed statistically using raw and log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pnfinity harmacokinetic parameters: AUC(0-t), AUC(0-infinity) Cmax, and Cmax/AUC(0-infinity) were within the range 80 - 125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis for the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax, and Cmax/AUC(0-infinity) were 88.93 - 107.10%, 89.09 - 107.11%, 89.63 - 108.58% and 96.85 - 105.29%, respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), and Cmax using the Schuirmann's two one-sided t-tests. Therefore, the two formulations were considered to be bioequivalent.     

Bioequivalence evaluation of two dosage forms of olanzapine 10 mg formulations in healthy volunteers

Two bioequivalence studies were carried out in healthy volunteers in order to compare the rate and extent of absorption of two dosage forms (film-coated tablet and orodispersible tablet) of oral olanzapine (CAS 132539-06-1) 10 mg test formulations and the respective brand formulations as reference. Twenty and twenty-six subjects were administered olanzapine film-coated tablet or orodispersible tablet of test and reference formulations in an open-label, randomised, fasting, two-period, two-sequence, crossover study. Blood samples were taken before and within 240 h after drug administration. Plasma concentrations were determined by LC/MS/MS. Log-transformed AUC and Cmax values were tested for bioequivalence based on the ratios of the geometric means (test/reference). tmax was analysed nonparametrically. The 90% confidence intervals of the geometric mean values for the test/reference ratios for AUC(0-t) and Cmax were within the bioequivalence acceptance range of 80-125%. It may be therefore concluded that the test formulations of olanzapine 10 mg film-coated tablet and orodispersible tablet are bioequivalent to the reference products and can be prescribed interchangeably.     

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.     

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.     

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 studies of film-coated tablet and chewable tablet generic formulations of montelukast in healthy volunteers

Two studies were conducted in order to assess the bioequivalence of montelukast (CAS 151767-02-1) 10 mg film-coated tablet (FCT) and 5 mg chewable tablet (CT) test formulations in comparison with the original brands. Under fasting conditions, healthy male and female volunteers received one 10 mg FCT or 5 mg CT orally as a single dose of a test or reference formulation. Both studies were designed as open-label, randomized, two-period, two-sequence, crossover studies with a 7-day washout interval. Plasma samples were collected up to 24 h after drug administration and montelukast levels were determined by a validated LC/ MS/MS method. Pharmacokinetic parameters were calculated using non-compartmental analysis and were statistically compared by analysis of variance for test and reference formulation. Bioequivalence between products was determined by calculating 90% confidence interval of the ratio test/reference of least-square means of logarithmically transformed Cmax and AUC0-t parameters. AUC0-infinity was also analysed to obtain additional information. The calculated 90% confidence intervals for the ratios of Cmax and AUC0-t parameters were 89.33-110.52 and 92.06-109.46, respectively, in the FCT study, and 91.58-101.86 and 92.15-98.83, respectively, in the CT study, which are all within the bioequivalence acceptance range of 80-125%. Based on the results, it can be concluded that the evaluated test FCT and CT formulations are bioequivalent to their respective reference formulation in terms of rate and extent of absorption.     

Bioequivalence evaluation of two brands of lisinopril tablets by in vitro comparative dissolution test and in vivo bioequivalence test

The bioequivalence of a test formulation (Nanopril, "test") and a reference formulation ("reference") of lisinopril (CAS 83915-83-7) was demonstrated by in vivo and in vitro tests. The in vivo bioequivalence study in 26 healthy volunteers was designed as a single dose, randomized, double-blind trial with a 2-week washout period between the doses. Prior to the in vivo study, an in vitro comparative dissolution test was performed by the paddle method following the bioequivalence guidance of the Korea Food and Drug Administration (KFDA). By the results of the dissolution test it was demonstrated from the similar and rapidly dissolving patterns of the two lisinopril tablets that the two formulations were pharmaceutically equivalent. However, the in vivo bioequivalence study was required to fully evaluate the bioequivalence of the two drug products. In the in vivo bioequivalence study, the plasma samples drawn from the volunteers were analyzed utilizing a sensitive LC-MS-MS analysis method and the bioequivalence between the two drug products was assessed by statistical analysis of the log transformed mean ratios of Cmax,AUC(0-t) and AUC(0-infinity). The mean maximum concentration (Cmax) of the test and reference were found to be 60.41 +/- 20.07 ng/mL and 61.11 +/- 19.36 ng/mL, respectively. The 90% confidence intervals (C.I.) of Cmax were in the range from 0.91 to 1.08. As for the AUC(0-t) and the AUC(0-infinity), test values were 792.73 +/- 273.41 ng x mL(-1) x h, 862.74 +/- 303.81 ng x mL(-1) x h and the reference values were 841.66 +/- 286.07 ng . mL(-1) x h, 906.97 +/- 318.72 ng x mL(-1) x h, respectively. The 90% C. I. of AUC(0-t) were 0.86 to 1.01 and of AUC(0-infinity), 0.87 to 1.02 and thus were within the 80-125% interval proposed by the FDA. In addition to the 90% C.I. of the pharmaceutical parameters, a two-way ANOVA showed no significant difference between the two formulations. Based upon these statistical analyses, it was concluded that the test formulation is bioequivalent to the reference.