Comparative bioavailability of slow release diclofenac (Voveran SR) with enteric coated tablet and internationally used Voltaren Retard.

The objective of the study was to compare the enteric coated diclofenac sodium (Voveran), the slow release formulation developed in India (Voveran SR) and the internationally marketed formulation Voltaren Retard. Ten healthy volunteers were administered 100 mg each of the three formulations in a three-way crossover fashion. Blood samples were collected over 24 hours following administration of the drug; plasma levels of unchanged drug were determined by gas chromatography. Pharmacokinetic parameters for the three formulations were compared. The extent of the drug available from the three formulations was the same as the mean AUC values were not significantly different. Cmax and MRT values for the two slow release formulations were comparable but were significantly different from the values obtained with the enteric coated formulation. Tmax values for the two slow release formulations were similar while the enteric coated tablet had faster time to peak. Voveran SR is comparable to Voltaren Retard and has the distinct advantage of a slow release formulation in that its Cmax is much lower and levels are maintained over 12 hours and detectable upto 24 hours. This slow release formulation will offer clinical advantages of better compliance, relief of early morning symptoms and better tolerability over long term usage.

Pharmacokinetics of primaquine in patients with P. vivax malaria.

The pharmacokinetics of primaquine (PQ) and its major carboxylic acid metabolite (PQC) have been studied in seven Indian patients with P. vivax malaria following PQ 15 mg/day p.o. for 14 days. After a single oral dose on Day 1, a mean peak blood concentration of 50.7 ng/ml PQ was attained after 2.3 h, which declined monoexponentially with a half-life of 5.6 h. The mean total body clearance was 37.6 l/h and the volume of distribution was 292 l. The mean renal excretion (0-24 h) of the drug was only 0.54% of the dose and renal clearance was 0.189 l/h. Following chronic administration, none of the pharmacokinetic parameters was affected, and a steady state blood concentration of 2.5-4.2 ng/ml PQ was attained. After the first dose of PQ, PQC had a mean area under the blood concentration - time curve 11-fold higher than that of the parent drug. In contrast to the rapid distribution and elimination of PQ, the metabolite showed a longer mean residence time and accumulation in the body. The mean Cmax and AUC of the metabolite on Day 14 were 48 and 40% higher than the corresponding Day 1 values. The metabolite could not be detected in urine at any time in any patient. PQ and its metabolite did not show any accumulation in blood cells.