[Absolute bioavailability of chlorpromazine, promazine and promethazine]. / Absolute Bioverfügbarkeit von Chlorpromazin, Promazin und Promethazin.

The absolute bioavailability of the three phenothiazine neuroleptics, promazine (Sinophenin, CAS 58-40-2), chlorpromazine (Propaphenin, CAS 50-53-3) and promethazine (Prothazin, CAS 60-87-7) was tested in three single-dose cross-over studies. In each trial 12 to 14 healthy volunteers were enrolled. The single doses for promazine, promethazine and chlorpromazine were 100, 75 and 150 mg (orally) and 20, 50 and 50 mg (intravenously), resp. The serum concentrations of the three neuroleptics were measured by means of a selective HPLC-method. the distribution-free confidence intervals for the absolute bioavailability of the three phenothiazines were within 10.5 to 24.7% for chlorpromazine, 7.8 to 24.9% for promazine and 12.3 to 40% for promethazine. Promazine and chlorpromazine are pharmacokinetically very similar and differ substantially from promethazine.

Differences in the bioavailability of dihydrotachysterol preparations.

The bioavailability of four preparations containing dihydrotachysterol (DHT2) was tested in two separate trials with administration of single, oral doses of 1 mg per individual. The relative bioavailability of corresponding preparations (capsules vs capsules and oral solution vs oral solution) was tested in a randomised, cross-over pattern within the same group of volunteers. Two different groups of 24 healthy volunteers took part in each trial. Solution and capsule bioavailability was also compared inter-individually. A new sensitive HPLC-method (quantification limit 0.5 ng.ml-1) was used for the measurement of DHT2 concentration in serum. Three of the preparations tested had a similar bioavailability (mean AUC values of 195.5-223 ng.h.ml-1); the bioavailability of the fourth preparation (A.T.10 oral solution) was considerably lower (mean AUC value 111.5 ng.h.ml-1). The present dosage recommendations of all four preparations are identical. A new dosage recommendation is thus required for the oral solution with low bioavailability (A.T.10).

[Pharmacokinetics and biotransformation of 3-cyan-2-morpholino-5-(pyrid-4-yl)pyridine (AWD 122-14) in the rat]. / Pharmakokinetik und Biotransformation von 3-Cyan-2-morpholino-5-(pyrid-4-yl)pyridin (AWD 122-14) an der Ratte.

A sensitive isocratic HPLC method for the analysis of AWD 122-14 (1) in plasma and urine was developed. The extraction was processed on-line on a short column. The pharmacokinetics of 1 was studied in rats. The plasma concentration-time course was described by an 1-compartment-model. The pharmacokinetic parameters were estimated. The absorption and elimination of 1 are relatively fast. A single oral dose (D = 1 x 10(-5) mol/kg) was rapidly absorbed (absorption rate constant: kI = 6.85 h-1). The elimination rate constant is kE = 1.59 h-1. The absolute bioavailability of a single oral dose equals 11%. In rats 1 is mainly metabolized. Less than 5% of the dose is excreted in the urine as unchanged drug. The chemical structures of 10 of the 12 isolated metabolites were determined using high-resolution mass spectrometry.