[Chronopharmacokinetics of the preparation biomet400 in patients with duodenal ulcer].

Biomet400 is a selective H2-blocker produced by the firm "Pharmacia" of the Bulgarian Medical Academy. 11 patients were treated with the drug in a dose of 400 mg taken orally in the morning or in the evening. The pharmacokinetic analysis revealed a slower resorption of cimetidine in the patients who had taken the drug in the evening (Tmax = 2 h, resp. 1.67 h) and a lowered Cmax (1.96 micrograms/ml, resp. 2.79 micrograms/ml) in comparison with the patients who had taken the drug in the morning. In the patients who had taken the drug in the evening the apparent volume of distribution is statistically significantly higher (242 l, resp. 124 l by the morning administration) and a tendency toward a slower elimination than by the morning administration is found (t1/2 = 4.41 h, resp. 3.89 h). In the patients who had taken the drug in the morning the elimination is mainly by renal excretion (Clr = 405 ml/min, resp. 3.29 ml/min for the evening administration) while in the patients with evening administration the nonrenal clearance prevails (Clnr = 534 ml/min, resp. 339 ml/min). The results indicate the presence of chronopharmacokinetic differences in the cimetidine action and they can explain the better chronotherapeutic results of the treatment with biomet400 administered in the evening.