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%.

Involvement of tyrosine kinase in peroxynitrite-induced preconditioning in rat isolated heart.

We have investigated the role of tyrosine kinase in the antiarrhythmic effects of peroxynitrite preconditioning in rat isolated heart by using a tyrosine phosphatase inhibitor, sodium orthovanadate, and tyrosine kinase inhibitors, genistein and tyrphostin. Rat hearts were preconditioned by peroxynitrite administration at 1 microM for 3 min, which was followed by 10-min washout and 30 min of ischemia. None of the hearts had ventricular fibrillation in the peroxynitrite preconditioning group (from 64%, n=11, to 0%, n=11). Neither sodium orthovanadate (10 microM) nor genistein (50 microM) or tyrphostin (100 microM) alone showed any effects on arrhythmias. Peroxynitrite preserved its beneficial effects on arrhythmias (to 0% ventricular fibrillation, n=7) during sodium orthovanadate infusion (for 23 min) prior to 30 min of an ischemic period. On the other hand, genistein or tyrphostin treatment significantly reversed the protective effects of the peroxynitrite preconditioning (to 71% ventricular fibrillation, n=14, genistein and, to 75% ventricular fibrillation, n=8, tyrphostin). These results suggest that the tyrosine kinase pathway plays a significant role in peroxynitrite-induced preconditioning in rat isolated heart.

Role of G(s) proteins in hypoxic constriction of sheep pulmonary artery rings.

The introduction of hypoxia is well known to cause contraction of pulmonary artery rings in vitro. Despite intensive studies, the cellular mechanisms of hypoxic pulmonary vasoconstriction are still not well defined. In this study, we aimed to determine the contribution of G(S) proteins in hypoxia-induced vasoconstriction in large-diameter sheep pulmonary arteries using cholera toxin (CT). Hypoxia caused further contractions in serotonin but not in NaF-precontracted pulmonary artery rings. However, hypoxic vasoconstriction due to lowering of pO(2) from 97 to 5 mm Hg was totally abolished by preincubation with CT in serotonin-precontracted arteries. These preliminary results indicate that signal transduction mediated by G(s) proteins may be an important mechanism in the hypoxic vasoconstriction of isolated pulmonary arteries of sheep.