[The bioavailability of nifedipine in different solid pharmaceutical preparations for oral use]. / Biodisponibilitatea nifedipinei din diferite preparate farmaceutice solide pentru uz oral.

The paper reports on the bioavailability of niphedipine in various pharmaceutic preparations administered in a single dose of 10 mg, per os, to volunteer subjects: Niphedipine dragees (Terapia, Cluj-Napoca), Adalat capsules (Bayer); Adalat coated tablets (Bayer and Birlasik Alman Ilac Fabricalari, Istanbul) and Corinfar dragées (VEB Arzneimittelwerk, Dresden). In the blood samples collected, niphedipine was determined by a gas-chromatographic procedure. Pharmacokinetic analysis of the experimental data was made by a digital computer. Bioavailability of niphedipine was the best with Adalat capsules. The relative bioavailability of the other products was: tablets (Adalat); 93%; dragées (Niphedipine): 92%; dragées (Corinfar 86%). Absorption speed of Niphedipine decreases in the order: capsules, tablets, indigenous and imported dragées. Statistical analysis (Student test) shows that the differences in bioavailability among the preparations are not important. Efficiently therapeutic plasmatic concentrations are maintained for about 6 hours after a single dose of 10 mg administered as tablets and dragées and for 8 hours in the case of capsules. Important differences exist between the maximum concentration of niphedipine in blood, following some differences in the absorption speed, achieved after administration of capsules, on the one hand, and of tablets and dragées on the other hand. Choosing the type of tablet depends, therefore, on the nature of the affection treated. Niphedipine (Terapia) has corresponding biopharmaceutic properties and is useful in treating hypertension and for preventing and treating anginal attacks.

Bioavailability of nifedipine from different oral dosage forms in healthy volunteers.

The absolute and relative bioavailability of nifedipine (1) from different formulations administered as single oral doses in healthy volunteers was determined. Serum concentrations of 1 were measured by GC. The absolute bioavailability of 1 was 53% because of presystemic metabolism. The bioavailability of Adalat (Bayer) tablets, Nifedipina (Terapia) and Corinfar (VEB Arzneimittelwerk Dresden) sugar-coated tablets was 93%, 92% and 86% (respectively) as compared with Adalat capsules. The AUC were not significantly different. The Cmax and tmax values were different, indicating that the absorption of 1 showed differences in first-order rate constants of dissolution in the above mentioned order. Despite the differences among the formulations studied, each preparation may have its merits. In a multiple dose regimen of 20 mg 1 (Nifedipina, Terapia) t.i.d., minimal therapeutic drug levels were achieved and maintained during steady state, from the 1st d of treatment.

A fatal case of trifluoperazine poisoning.

A fatal case of trifluoperazine poisoning is reported. Case history, pathological findings, and the concentrations of trifluoperazine and its metabolites in blood, liver, and kidney are presented.