Insufficient recovery of monoamine oxidase in a bioequivalence study of the monoamine oxidase inhibitor tranylcypromine: Recommendation of the tranylcypromine enantiomer test.

OBJECTIVE: To investigate the recovery of monoamine oxidase (MAO) activity in the liver and gut of healthy subjects after a dose of 10 mg of the irreversible MAO inhibitor tranylcypromine (TCP). MATERIALS AND METHODS: A bioequivalence study of TCP with a wash-out of 1 week between 2 doses of 10 mg TCP was re-analyzed for changes of the plasma concentrations of TCP enantiomers. Plasma concentrations of (+)-TCP and the ratio of (+)-TCP and (-)-TCP plasma concentrations were used as a measure of MAO activity because (+)-TCP is a more effective suicide inhibitor of MAO than (-)-TCP and, therefore considerably more metabolized by MAO. RESULTS: The area under the curve from the first to the last measured concentration (AUCt) and the maximum plasma concentration (Cmax) of (+)-TCP increased significantly in the second dose (p < 0.0001) by 43.1% (11.8%) and 66.5% (26.4%), respectively, (mean with 95%CI in each case). The ratios (+)-TCP/(-)-TCP of AUCt and Cmax also increased significantly (p < 0.0001) by 27.3% (6.4%) and 25.9% (6.2%), respectively. No changes were found for the half-lives (T1/2) of both enantiomers. CONCLUSION: For the first dose, MAO is the main drug-metabolizing enzyme of (+)-TCP. MAO activity in the liver and gut is not completely recovered within 1 week after 1 dose of TCP. One week of wash-out may be insufficient in bioequivalence studies of irreversible MAO inhibitors. Prolonged inhibition of MAO after the treatment with irreversible MAO inhibitors may explain drug interactions during the switch from another MAO inhibitor to TCP. Enantiomer plasma concentrations of TCP after a dose of racemic TCP may be used as a test for gastrointestinal and hepatic MAO activity.

Bioequivalence study of two favipiravir tablet formulations in healthy male subjects.

OBJECTIVE: The global pandemic called COVID-19 has dragged the world into a healthcare crisis, and favipiravir is one of the most prescribed agents against the virus so far. Favipiravir is a repurposed antiviral agent in treatment of SARS-CoV-2 infection, and to meet the current need, pharmaceutical companies are working for manufacturing licensed generic favipiravir. For getting the marketing authorization, the bioequivalence of the generic product must be proven first. The aim of this study is to demonstrate the bioequivalence of a new favipiravir tablet formulation as compared to the reference tablet formulation in healthy male subjects under fasting conditions. MATERIALS AND METHODS: To prove the bioequivalence, a randomized, single oral dose, cross-over, two-period study was carried out in 30 healthy subjects under fasting conditions. Plasma favipiravir levels were quantified by using an in-house-developed high performance liquid chromatography with mass spectrometry detector (LC-MSD) method. RESULTS: The 90% CIs for the test/reference geometric mean ratios of the Cmax and AUC0-tlast were 88.02 - 103.11% and 98.19 - 102.06%, respectively. CONCLUSION: This single-dose study has shown that the test and reference favipiravir products met the required bioequivalence criteria. Besides, both products were well tolerated and safe.

Proton pump inhibitors omeprazole, lansoprazole and pantoprazole induce relaxation in the rat lower oesophageal sphincter.

OBJECTIVES: We aimed to investigate effects of the proton pump inhibitors (PPIs) omeprazole, lansoprazole and pantoprazole, which are currently used for the treatment of hyperacidity and gastro-oesophageal reflux, on the reactivity of the isolated rat lower oesophageal sphincter. METHODS: Omeprazole, lansoprazole and pantoprazole (all 10(-9) -10(-3) m, cumulatively) were tested on carbachol-induced (10(-6) m) contraction. In addition, the effects of PPI preincubation (all 10(-3) m) on the contractions induced by cumulative carbachol (10(-9) -10(-5) m), angiotensin-2 (10(-9) -10(-5) m) or electrical field stimulation (EFS; 40 V, 32 Hz, 1 ms, 10 s) were assessed. Finally, the effects of PPI on the spontaneous contractile activity of the tissue were also evaluated. KEY FINDINGS: PPI relaxed precontracted lower oesophageal sphincter in a concentration-dependent manner and suppressed carbachol-, angiotensin- and EFS-induced contractions. Furthermore, PPI attenuated spontaneous contractile activity of the tissue. CONCLUSIONS: Omeprazole, lansoprazole and pantoprazole had a suppressor effect on lower oesophageal sphincter contractions.

Bioequivalence study of two different clopidogrel bisulfate film-coated tablets.

OBJECTIVE: The aim of the present study was to evaluate the bioequivalence of two oral clopidogrel (CAS 113665-84-2) formulations. METHOD: The study was conducted as a monocentric, open, randomized, single-dose, two-period crossover trial in 48 healthy volunteers with a duration of hospitalization of approximately 24 h after dosing on day 1 and with a real wash-out period of 7 days. Blood samples were collected for 24 h post dosing in each period. The plasma was separated and the concentrations of clopidogrel were determined by a LC-MS/MS method. AUC(0-tlast), Cmax, tmax, AUC(0-inf), MRT and t1/2 were calculated for both formulations. RESULTS: The arithmetic means of AUC(0-tlast) and Cmax were 3,656.01 pg x h/ml and 1970.22 pg/ml for the test formulation and 3771.51 pg x h/ml and 1756.52 pg/ml, respectively, for the reference formulation. The mean tmax was 1.16 h for the test and 1.13 h for the reference formulation. The point estimators of the ratios of the test and reference formulations for AUC(0-tlast) and Cmax were 1.042 and 1.115, respectively. Furthermore, the 90% confidence intervals calculated by means of ANOVA-log for the first primary endpoint of the trial, the intra-individual ratio (T/R) of AUC(0-tlast) of clopidogrel was between 0.932 and 1.165. The 90% confidence interval calculated by means of ANOVA-log for Cmax of clopidogrel was between 0.973 and 1.277. The 90% confidence intervals for both parameters were within the predefined acceptance ranges (0.80-1.25 for AUC(0-tlast) and 0.75-1.33 for Cmax). The intraindividual coefficients of variation determined by means of ANOVA-log were 33.51% for AUC(0-tlast) and 41.29% for Cmax. CONCLUSION: While both products were bioequivalent in terms of the rate and extent of absorption, the present study also confirmed a high variability for clopidogrel suggesting high volunteer numbers in bioequivalence trials.

Pharmacokinetics and bioequivalence study of a generic amlodipine tablet formulation in healthy male volunteers.

Two different tablets containing amlodipine besylate (CAS 111470-99-6) (Vazkor 10 mg tablet as test preparation and 10 mg tablet of the originator product as reference preparation) were investigated in 18 healthy male volunteers in order to compare the bioavailability and prove the bioequivalence between both treatments after oral single dose administration. The study was performed according to an open-label, randomized, two-period cross-over design with a wash-out phase of 21 days. Blood samples for pharmacokinetic profiling were taken up to 144 h post-dose, and amlodipine plasma concentrations were determined with a validated LC-MS/MS method. Maximum plasma concentrations (Cmax) of 6,183.7 pg/ml (test) and 5,366.7 pg/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 267,231.0 pg x h/ml (test) and 266,061.7 ng x h/ml (reference) were calculated. The median tmax was 5.6 h (test) and 6.1 h (reference). Plasma elimination half-lives (t 1/2) were 46.46 h (test) and 45.34 h (reference). Both primary target parameters AUC(0-infinity) and Cmax were tested parametrically by analysis of variance (ANOVA); 90% confidence intervals were between 93.20%-107.16% (AUC(0-infinity) and 103.36%-123.13% (Cmax). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and Cmax the 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.

Pharmacokinetics and bioequivalence study of ranitidine film tablets in healthy male subjects.

The aim of the present study was to compare the bioavailability of ranitidine (CAS 66357-35-5) from two different ranitidine hydrochloride (CAS 66357-59-3) film tablets (Ranitab 150 mg film tablets as test preparation and 150 mg film tablets of the originator product as reference preparation). The study was conducted according to an open-label, randomised two-period cross-over design with a wash-out phase of 9 days. Blood samples for pharmacokinetic profiling were taken up to 24 h post-dose, and ranitidine plasma concentrations were determined with a validated HPLC method with UV-detection. Maximum plasma concentrations (Cmax) of 461.8 ng/ml (test) and 450.6 ng/ ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC (0-infinity) of 2,488.6 ng . h/ml (test) and 2,528.8 ng . h/ml (reference) were calculated. The median tmax was 2.83 h (test) and 3.04 h (reference). Plasma elimination half-lives (t1/2) of 2.78 h (test) and 2.89 h (reference) were determined. Both primary target parameters AUC(0-infinity) and Cmax were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 91.93 %-106.98 % (AUC (0-infinity) and 92.34%-118.85% (Cmax). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and Cmax the 90 % confidence intervals of the T/R ratios of logarithmically transformed data were in the generally accepted range of 80 %-125 %.

Pharmacokinetics and bioequivalence study of doxycycline capsules in healthy male subjects.

The aim of the present study was to compare the bioavailability of doxycycline (CAS 564-25-0) from two different doxycycline hyclate (CAS 24390-14-5) capsules (Monodoks 100 mg capsule as test preparation and 100 mg capsule of the originator product as reference preparation) in 24 healthy male subjects. The study was conducted according to an open-label, randomised two-period cross-over design with a wash-out phase of 16 days. Blood samples for pharmacokinetic profiling were taken up to 72 h post-dose, and doxycycline plasma concentrations were determined with a validated HPLC method with UV-detection. Maximum plasma concentrations (Cmax) of 1,715.1 ng/ml (test) and 1,613.3 ng/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 28,586.5 ng x h/ml (test) and 29,047.5 ng x h/ml (reference) were calculated. The median tmax was 1.88 h (test) and 2.00 h (reference). Plasma elimination half-lives (t1/2) of 16.49 h (test) and 16.75 h (reference) were determined. Both primary target parameters AUC(0-infinity) and Cmax were tested parametrically by analysis of variance (ANOVA) and the 92.39 %-103.53% (AUC(0-infinity)) and 98.45%-111.74% (Cmax). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and Cmax the 90% confidence intervals of the T/R ratios of logarithmically transformed data were in the generally accepted range of 80 0%-125%.

Pharmacokinetic and bioequivalence study of meloxicam tablets in healthy male subjects.

Meloxicam (CAS 71125-38-7), a non-steroidal anti-inflammatory drug (NSAID), is used for the treatment of osteoarthritis and rheumatic arthritis. In the present study, two different oral meloxicam formulations (Melcam 15 mg tablets as test preparation and tablets of a reference preparation) were investigated in 24 healthy male subjects in order to prove bioequivalence between both preparations. A single 15 mg oral dose was administered according to an open, randomised, two-period cross-over design in the fasted state. Blood samples for the determination of meloxicam plasma concentrations were collected at pre-defined time points up to 96 h following drug administration. A wash-out period of 7-8 days separated both treatment periods. Meloxicam plasma concentrations were determined by means of a validated HPLC method with UV-detection. Maximum plasma concentrations (C(max)) of 1,146.9 ng/ml (test) and 1,064.8 ng/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity) of 34,499.0 ng x h/ml (test) and 33,784.3 ng x h/ml (reference) were determined. The results showed nearly identical rate and extent of drug absorption. Also further pharmacokinetic parameters were well comparable. Thus, t(max) showed values of 5.00 h for both test and reference. The plasma elimination half-life (t1/2) was 18.29 h (test) und 18.94 h (reference). Both primary target parameters C(max). and AUC(0-infinity, were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 99.46%-105.24% (AUC0-infinity)) and 103.37%-112.46% (C(max)). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and C(max) the 90% confidence intervals of the T/R ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.

Comparative pharmacokinetics of two tablet formulations of amoxicillin: bioequivalence assessment.

The aim of the present study was to compare the bioavailability of amoxicillin (CAS 26787-78-0) from two different amoxicillin tablets (Demoksil 1 g tablet as test preparation and 1 g tablet of the originator product as reference preparation). The study was conducted according to an open-label, randomised two-period cross-over design with a wash-out phase of 4-7 days. Blood samples for pharmacokinetic profiling were taken up to 10 h post-dose, and amoxicillin plasma concentrations were determined with a validated LC-MS/ MS method. Maximum plasma concentrations (C(max)) of 13,296.4 ng/ml (test) and 12,797.7 ng/ml (reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity)) of 39,556.7 ng x h/ml (test) and 38,599.1 ng x h/ml (reference) were calculated. The median t(max) was 1.62 h (test) and 1.54 h (reference). Plasma elimination half-lives (t(1/2)) of 1.64 h (test) and 1.65 h (reference) were determined. Both primary target parameters, AUC(0-infinity) and C(max) were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 96.76%-108.46% (AUC(0-infinity)) and 97.80%-111.98% (C(max)). Bioequivalence between test and reference preparation was demonstrated since for both parameters, AUC and C(max) the 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.

Bioequivalence study of sultamicillin suspensions.

Sultamicillin (CAS 76497-13-7) is a prodrug combination of ampicillin (CAS 69-53-4) and sulbactam (CAS 68373-14-8), with the antibiotic ampicillin and the beta-lactamase inhibitor sulbactam chemically linked as double ester. The present study was performed to investigate the relative bioavailability and to assess the bioequivalence of two different sultamicillin suspensions (Devasid 250 mg/5 ml as test preparation and 375 mg/7.5 ml of the originator product as reference preparation). Twenty-four healthy male volunteers received equal doses of the sultamicillin preparations according to an open, randomised, single-dose, two-period cross-over design with a wash-out phase of 7 days. Blood samples for pharmacokinetic profiling were taken up to 8 h post-dose, and ampicillin and sulbactam plasma concentrations were determined with a validated LC-MS/MS method. Maximum plasma concentrations (C(max)) of 11,267.4 ng/ml (ampicillin, test), 10,864.4 ng/ml (ampicillin, reference), 6,360.6 ng/ml (sulbactam, test and 6,410.7 ng/ml (sulbactam, reference) were achieved. Areas under the plasma concentration-time curve (AUC(0-infinity) of 17,512.9 ng x h/ml (ampicillin, test), 18,388.0 ng x h/ml (ampicillin, reference), 10,971.7 ng ng x h/ml (sulbactam, test) and 11,181.2 ng x h/ml (sulbactam, reference) were calculated. The median t(max) was 0.69 h (ampicillin, test), 0.85 h (ampicillin, reference), 0.72 h (sulbactam, Devasid) and 0.83 h (sulbactam, reference). Plasma elimination half-lives (t(1/2)) of 1.04 h (ampicillin, test), 1.03 h (ampicillin, reference), 1.26 h (sulbactam, Devasid) and 1.00 h (sulbactam, reference) were determined. Both primary target parameters AUC(0-infinity) and C(max) of ampicillin and sulbactam were tested parametrically by analysis of variance (ANOVA) and the 90% confidence intervals were between 84.58%-117.80% (AUC(0-infinity), ampicillin), 92.37%-119.93% (C(max), ampicillin), 85.81%-120.50% (AUC(0-infinity), sulbactam) and 88.41%-117.57% (C(max), sulbactam). Bioequivalence between test and reference preparation was demonstrated since for both parameters AUC and C(max) the 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%.

Assessment of the bioequivalence of different formulations containing azithromycin (tablets and suspension).

Azithromycin (CAS 11772-70-0) is an orally administered macrolide antimicrobial drug, structurally related to erythromycin, with a similar spectrum of antimicrobial activity. The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of azithromycin (Azro) 500 mg tablets (study 1) and azithromycin (Azro) 200 mg/5 mL suspensions (study 2) with originator products. Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in 24 healthy volunteers with a wash-out period from 14 to 21 days. Blood samples were taken up to 96 h post dosing, and concentrations of azithromycin were determined by HPLC method. In the first study, the 90% confidence interval for intra-individual ratios (test vs. reference) of AUC0-t and Cmax of azithromycin were between 0.82 and 1.04 for AUC0-t and 0.81 and 1.11 for Cmax, and thus within the acceptance ranges for bioequivalence trials. The 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of azithromycin administered as suspension were between 0.89 and 1.22 and 0.91 and 1.23, respectively. These values were also within the acceptance range. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences for azithromycin were between -0.49 - 0.50 in the first and between -0.50 - 0.25 in the second study, respectively. In the light of the results of the studies reported here it can be concluded that azithromycin test formulations, i.e. tablet and suspension are bioequivalent to the respective reference formulations.

Bioequivalence study of atorvastatin tablets.

The study was designed to evaluate the relative bioavailability of two formulations of atorvastatin (CAS 134523-03-8). A bioequivalence study was carried out in 24 healthy male volunteers who received four 10 mg tablets of the test formulation (Kolestor) and the same dose of the originator product. The trial was performed according to an open, crossover design with a wash-out period of 7 days in one study center. Blood samples were taken up to 48 h post dose, the plasma was separated and the concentrations of atorvastatin were determined by HPLC-MS-MS method. The mean Cmax were 16.37 ng/mL and 17.05 ng/mL, while the mean AUC0-t were 103.61 ng x h/mL and 102.55 ng x h/mL for the test and reference formulations, respectively. The mean AUC0-inf were 118.10 ng x h/mL and 117.13 ng x h/mL for the test and reference formulations, respectively. The median tmax was 0.67 h for both the test tablet and the reference product. The mean t(1/2 el) was 11.85 h for the test formulation and 13.28 h for the reference formulation. No significant differences of pharmacokinetic parameters between the two studied formulations were found. The 90% confidence intervals for the primary target parameters, intra-individual ratios of AUC0-t and Cmax of atorvastatin, were between 0.85 and 1.05 (AUC0-t) and between 0.84 and 1.23 (Cmax), respectively, and thus within the acceptance ranges. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences was between -0.17 and 0.17 h. In the light of the present study it can be concluded that the two evaluated atorvastatin formulations, i.e. test formulation of atorvastatin and reference preparation are bioequivalent in terms of the rate and extent of absorption.

Studies on the bioequivalence of second generation cephalosporins: cefaclor capsules and suspension.

The aim of the present studies, performed in two different groups of volunteers, was to prove the bioequivalence of 500 mg cefaclor (CAS 70356-03-5) test and reference capsules (Losefar 500 mg Capsules as test and an originator product as reference; study 1) and cefaclor 250 mg/5 mL test and reference suspensions (Losefar 250 mg/5 mL Granules oral suspension as test and an originator product as reference; study 2). Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 8 h post dosing, and concentrations of cefaclor were determined by HPLC method. In the first study, the 90% confidence intervals for intra-individual ratios of AUC0-t and Cmax of cefaclor were 0.99-1.08 for AUC0-t and 0.82-1.06 for Cmax, and thus within the acceptance ranges for bioequivalence trials. The 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of cefaclor administered as suspensions were 1.10-1.19 and 1.02-1.21, respectively. These values were also within the acceptance range. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences for cefaclor were between -0.13 - 0.13 in the first and between 0.00 - 0.13 in the second study, respectively. In the light of the results of the studies reported here it can be concluded that cefaclor test formulations, i.e. capsules and suspension are bioequivalent to the respective reference formulations.

Studies on the bioequivalence of different strengths of tablets containing clarithromycin.

The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of clarithromycin (CAS 81103-11-9) tablets (Klaromin, test tablets) containing 250 mg (study 1) or 500 mg (study 2) of the drug with reference tablets of the same strength. Each study was conducted according to an open, randomized, single-dose, two-period crossover design in healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 24 h in both studies, and concentrations of clarithromycin and its principal active 14-hydroxy metabolite were determined by HPLC method. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of clarithromycin were between 0.93 and 1.05 (AUC0-t) as well as between 0.90 and 1.18 (Cmax). In the second study, i.e. after administration of clarithromycin 500 mg tablets, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of clarithromycin were between 0.90 and 1.08 (AUC0-t) as well as between 0.85 and 1.22 (Cmax). All these values were within the acceptance ranges for bioequivalence studies. In both studies, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of 14-hydroxy-clarithromycin were also within the acceptance ranges, although the confidence intervals for these parameters were not planned to be compared with the acceptance ranges. In the light of the results of the studies reported here it can be concluded that the clarithromycin 250 mg and 500 mg test tablets are bioequivalent to the respective reference formulations.

Clarithromycin suspension: bioequivalence studies on two different strengths.

Two studies were performed in different groups of volunteers, with the aim to prove the bioequivalence of test (Klaromin) and reference clarithromycin (CAS 81103-11-9) suspensions containing in 5 mL either 125 mg (study 1) or 250 mg (study 2) of the drug, administered as an oral dose of 10 mL. Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 24 h in both studies, and concentrations of clarithromycin and its principal active 14-hydroxy metabolite were determined by HPLC. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of clarithromycin were between 0.84 and 1.03 (AUC0-t) and between 0.89 and 1.03 (Cmax). In the second study, i.e. after administration of clarithromycin suspension 250mg/5mL, the 90% confidence interval for intra-individual ratios of AUC0-inf and Cmax of clarithromycin were between 1.01 and 1.17 (AUC0-inf) and between 1.01 and 1.16 (Cmax). All these values were within the acceptance ranges for bioequivalence studies. In both studies, the 90% confidence interval for intra-individual ratios of AUC0-inf and Cmax of 14-hydroxy-clarithromycin were also within the acceptance ranges. In the light of the results of the studies reported here it can be concluded that the clarithromycin test formulations are bioequivalent to the respective reference formulations, i.e. suspensions containing 125 mg/5 mL and 250 mg/5 mL of the drug.

Effect of the combination of lisinopril and hydrochlorothiazide on the bioequivalence of tablet formulations.

The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of 20 mg lisinopril tablets (Sinopryl as test and an orignator product as reference formulation; study 1) and lisinopril/hydrochlorothiazide (20 mg/12.5 mg) (CAS 83915-83-7/CAS 58-93-5) combined formulations (Sinoretik as test and an originator product as reference formulation; study 2). Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 72 h in both studies, the plasma was separated. Concentrations of lisinopril and hydrochlorothiazide were determined by HPLC-MS-MS method. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of lisinopril were between 0.85 and 1.12 (AUC0-t) and between 0.87 and 1.17 (Cmax), and thus within the acceptance ranges. In the second study, i.e. after administration of combined lisinopril/hydrochlorothiazide formulations, the 90% confidence interval for intra-individual ratios of AUC0-inf and Cmax of lisinopril were between 0.83 and 1.22 (AUC0-inf) and between 0.80 and 1.25 (Cmax). The 90% confidence interval for intra-individual ratios of AUC0-inf and Cmax of hydrochlorothiazide were between 0.92 and 1.04 (AUC0-inf) and between 0.88 and 1.08 (Cmax). All the above values were within the acceptance ranges for bioequivalence studies. In the light of the present studies it can be concluded that Hsinopril as well as lisinopril/hydrochlorothiazide test formulations are bioequivalent to the respective reference formulations.

Combination of losartan and hydrochlorothiazide: in vivo bioequivalence.

Two trials were performed in different groups of volunteers with the aim to compare the bioavailability of 50 mg losartan tablets (Sarvas as test and an originator product as reference formulation; study 1) and losartan/hydrochlorothiazide (50 mg/12.5 mg) (CAS 124750-99-8/CAS 58-93-5) combined formulations (Sarvastan as test and an originator product as reference formulation; study 2), respectively. Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in 24 healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 36 h in the first study and up to 48 h in the second study. Concentrations of losartan and its principal active metabolite, i.e. E3174, as well as hydrochlorothiazide were determined by HPLC or LC-MS-MS, respectively. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of losartan were between 0.91 and 1.03 (AUC0-t) as well as between 0.87 and 1.19 (Cmax), and thus within the acceptance ranges. The 90% confidence interval for intra-individual ratios of AUC0-t, and Cmax of E3174 were between 0.90 and 1.13 for AUC0-t, and between 0.97 and 1.14 for Cmax. In the second study, i.e. after administration of combined losartan/hydrochlorothiazide formulations, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of losartan were between 0.90 and 1.04 (AUC0-t) as well as between 0.86 and 1.20 (Cmax). Similarly to the parent compound, no significant differences of bioavailability parameters of E3174 between the two studied formulations were found. The 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of hydrochlorothiazide were between 0.89 and 0.98 (AUC0-t) as well as between 0.82 and 1.00 (Cmax). In the light of the present studies it can be concluded that the losartan as well as losartan/hydrochlorothiazide test formulations are bioequivalent to the respective reference formulations.

Bioequivalence study of rofecoxib tablets.

The study was designed to evaluate the bioavailability of two rofecoxib (CAS 162011-90-7) tablet formulations. Twenty-four healthy male volunteers were administered a 25 mg tablet of the test formulation (Ecrox) containing rofecoxib or the originator product (reference). The trial was performed according to an open, cross-over design with a wash-out period of 7 days. Blood samples were taken up to 72 h post dose, the plasma was separated and the concentrations of rofecoxib were determined by an HPLC method. The mean Cmax were 192.07 ng/mL and 187.35 ng/mL, while the mean AUC0-t were 3613.84 ng x h/mL and 3501.56 ng x h/mL for the test and reference formulations, respectively. The median tmax was 3.75 h for the test tablet and 4.00 h for the reference formulation. The mean t(1/2 el) was 10.66 h and 10.61 h for the test and reference formulation, respectively. Mean MRT values for the test and reference tablets were 15.34 h and 15.33 h, respectively. Mean MRT values for the test and reference tablets were 15.34 h and 15.33 h, respectively. No significant differences of pharmacokinetic parameters between the two studied formulations were found. The 90% confidence interval for the primary target parameters, i.e. intra-individual ratios of AUC0-t and Cmax of rofecoxib were between 0.99 and 1.10 (AUC0-t) as well as between 0.96 and 1.10 (Cmax) and thus within the acceptance ranges. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences was between -0.25 and 0.25 h. In the light of the present study it can be concluded that the two evaluated rofecoxib formulations, i.e. test tablets of rofecoxib and a reference preparation are bioequivalent in terms of the rate and extent of absorption.

Serotonin reuptake inhibitors: bioequivalence of sertraline capsules.

The study was designed to evaluate the bioavailability of two sertraline (CAS 79617-96-2) formulations. A bioequivalence study was carried out in 24 healthy male volunteers, who were administered 50 mg capsules of the test formulation (Seralin) and the originator product (reference) as a single dose. The trial was performed according to an open, randomized, cross-over design with a washout period of 14-20 days in one study center. Blood samples were taken up to 96 h post dose, the plasma was separated and the concentrations of sertraline were determined by HPLC-MS-MS. The mean Cmax were 9.01 +/- 2.26 ng/mL and 8.24 +/- 2.14 ng/mL, while the mean AUC0-t were 259.09 +/- 105.36 ng x h/mL and 234.36 +/- 95.18 ng x h/mL for the test and reference formulations, respectively. The mean AUC0-inf were 292.66 +/- 128.09 ng x h/mL (test) and 267.23 +/- 116.40 ng x h/ mL (reference). The mean tmax was 5.88 +/- 1.03 h for the test capsules and 6.17 +/- 1.66 h for the reference formula. The mean t1/2el was 26.49 +/- 6.45 h for the test formulation and 26.23 +/- 6.64 h for the reference formulation. Mean MRT values for the test and reference formulations were 28.14 +/- 5.37 h and 27.81 +/- 5.13 h, respectively. No significant differences of pharmacokinetic parameters between the two studied formulations were found. The 90% confidence interval for the primary target parameters, intra-individual ratios of AUC0-t and Cmax of sertraline were between 1.03 and 1.19 (AUC0-t) as well as between 1.02 and 1.17 (Cmax) and thus within the acceptance ranges for bioequivalence trials. Concerning the secondary parameter tmax the 90% confidence interval for the intra-individual differences was between -1.00 and 0.50 h. In the light of the present study it can be concluded that sertraline test capsules are bioequivalent to the reference formulation.

Effect of the formulation on the bioequivalence of sultamicillin: tablets and suspension.

Sultamicillin (CAS 76497-13-7) is a pro-drug of a combination of ampicillin and sulbactam linked as a double ester. The aim of the present studies, performed in two different groups of volunteers, was to compare the bioavailability of 750 mg sultamicillin tablets (Duobaktam 750 mg tablets, study 1) and sultamicillin 250 mg/5mL suspensions (Duobaktam 250 mg/5mL, study 2). Each study was conducted according to an open, randomized, single-dose, two-period cross-over design in 24 healthy volunteers with a wash-out period from 7 to 14 days. Blood samples were taken up to 12 h post dosing, and concentrations of ampicillin and sulbactam were determined by a HPLC-UV method. In the first study, the 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of ampicillin and sulbactam were between 1.01-1.18 and 0.95-1.09 (AUC0-t) as well as between 0.87-1.04 and 0.80-0.96 (Cmax), respectively, and thus within the acceptance ranges. The 90% confidence interval for intra-individual ratios of AUC0-t and Cmax of sultamicillin suspensions (2nd study) were between 0.94-1.16 (ampicillin) and 0.92-1.14 (sulbactam) for AUC0-t and between 0.96-1.23 (ampicillin) and 0.97-1.24 (sulbactam) for Cmax. These values were also within the acceptance range for bioequivalence studies. Concerning the secondary parameter tmax the 90%-confidence interval for the intra-individual differences for both ampicillin and sulbactam were between 0.00-0.50 in the first and between -0.17-0.00 in the second study, respectively. In the light of the present studies it can be concluded that the sultamicillin test formulations, i.e. tablet and suspension are bioequivalent to the respective reference formulations.