Comparative bioavailability study of a conventional and two controlled release oral formulations of Tegretol (carbamazepine)--200 mg.

OBJECTIVES: To assess the bioquivalence of carbamazepine (CBZ) controlled release formulation A (Tegretol CR, local) vs formulation B (Tegretol CR, Basel) and confirm their controlled release characteristics by comparing with conventional formulation (Tegretol). METHODS: A three-way randomized cross-over bioavailability study was carried out using CBZ 200 mg tablets of conventional and two controlled release formulations in twelve healthy volunteers. Coded plasma samples were analysed for levels of CBZ by HPLC method. RESULTS: The mean Cmax, Tmax, t1/2 and AUC for formulation A were: 1.67 +/- 0.26 mcg/mL, 24 +/- 0 hr, 47.8 +/- 9.7 hr and 136.7 +/- 25.4 mcg/ml. h; for formulation B were 1.41 +/- 0.31 mcg/mL, 25 +/- 8 hr, 46.9 +/- 7.9 and 119 +/- 32.3 mcg/ml.h and for conventional formulation were 2.43 +/- 3.6 mcg/mL, 9.5 +/- 7.4 hr, 44.6 +/- 9.8 hr and 178.8 +/- 41.9 mcg/ml.h respectively. The fluctuation in plasma concentration within 24 h (peak:trough) were 11.7 +/- 8.14% with conventional formulation as compared to 0% and 1.2 +/- 3.98% with formulation A and B respectively. The mean Tmax for both the controlled release formulations was not statistically significant. On the basis of 90% confidence interval, mean AUC and Cmax values obtained after controlled release formulation A, though statistically significant (P < 0.05) lie well within the prescribed limits of 80-120% as compared to formulation B. Thus both the controlled release formulations were bioequivalent. In comparison to conventional formulation, both controlled release formulations gave lower Cmax, lower AUCs, higher Tmax values, less fluctuation in CBZ plasma concentrations, reduction in ratio of Cmax/AUC values, thus demonstrating controlled release characteristics of the formulation. CONCLUSIONS: Based on the above mentioned parameters both controlled release formulations are bioequivalent and demonstrate controlled release characteristics.

Comparison of absorption rate and bioavailability of two brands of carbamazepine.

OBJECTIVE: To assess the bioavailability of carbamazepine from two brands of carbamazepine--Tegretol 200 and Zen-200. METHODS: A two-way randomised cross-over bioavailability of carbamazepine was carried out in twelve healthy male volunteers. Coded plasma samples were analysed for levels of carbamazepine by high performance liquid chromatography (HPLC) method. Tegretol 200 and Zen-200 were tested for in-vitro dissolution profiles. RESULTS: The mean Cmax, Tmax and t1/2a for Tegretol 200 were: 2.17 +/- 0.42 mcg/mL, 11.67 +/- 6.37 h and 2.72 +/- 1.87 h; for Zen-200 were 3.10 +/- 0.05 mcg/mL, 3.50 +/- 2.11 h and 0.76 +/- 0.76 h respectively. These values were statistically significant. However AUC (0-96 h) value of 150.16 +/- 27.13 mcg/ml.h after Zen-200 was not statistically significant as compared to 128.68 +/- 20.22 mcg/ml.h after Tegretol 200. The in-vitro dissolution profiles of the two formulations were dissimilar. The fluctuations in CBZ levels after Tegretol 200 was significantly less as compared to Zen-200. The absorption profile as judged by parameter 'A' was 50.44 +/- 10.95 for Tegretol 200 and 42.49 +/- 18.89 for Zen-200. CONCLUSION: Based on parameter 'A' and other pharmacokinetic parameters, the marketed generic carbamazepine product, Zen-200 is not bioequivalent to Tegretol 200.

Patterns of rheumatic diseases and antirheumatic drug usage in 11931 Indian patients.

Patterns of rheumatic diseases and antirheumatic drug usage in different regions of India were analysed. The data was collected from a post-marketing surveillance of diclofenac sodium (Voveran) in 11931 patients. The common conditions were-rheumatoid arthritis (RA) 28.1%, osteoarthrosis (OA) 24.8%, soft-tissue rheumatism 12.4%, cervical spondylosis 6%, ankylosing spondylitis (AS) 3.5%, gout 2%. East zone had a significantly lower proportion of osteoarthritis (20.9%). The age distribution and sex ratios of RA, OA and AS were in line with literature reports. The severity of illness was moderate in 62% and duration was more than 6 months in 50.2%. Data on NSAID usage showed a preponderance of combinations and ibuprofen. There were no significant differences in NSAID usage across diseases or regions.