Pharmacokinetics of piracetam: a study on the bioavailability with special regard to renal and non-renal elimination.

The basis of this investigation was a trial on the relative bioavailability of a recently developed galenic formulation of piracetam. The open, randomized, single-blind crossover study was performed in 16 healthy male volunteers aged between 20 and 31 years. Under fasting conditions, they were given a single oral dose of 1600 mg piracetam either of the test drug or the reference drug. Blood samples and urine specimens were collected over 24 hours. The quantitative analysis was performed with a high sensitive HPLC-method. The pharmacokinetic analysis was carried out with the PC-based program TopFit. An identical bioavailability of the test drug was found (AUC0-24, AUC0-infinity, Cmax, by comparison to the reference drug. No relevant difference in piracetam excretion between test and reference drug was found, however, in contrast to previous references only about two thirds of the given oral dose could be detected in the urine after administration. A statistically significant difference (p = 0.001) between total clearance and renal clearance was observed. Because an incomplete absorption of the drug in the upper gastrointestinal tract is excluded, an additional extrarenal pathway of piracetam must be discussed; the hypothesis of an exclusive renal elimination of this drug should be overruled.

[Gastrointestinal absorption of theophylline, especially with reference to retard preparations]. / Zur gastrointestinalen Absorption von Theophyllin insbesondere im Hinblick auf Retardpräparate.

Little is known about the absorption of theophylline from definite parts of the intestine, though there are many depot or slow-release formulations of theophylline on the market and this topic should be of relevant importance. Most of these formulations are releasing the drug for up to 24 hours while passing the bowels. In this prospective, open, randomised, study with an interchange trial design the absorption of theophylline from the colon was studied in eight healthy male volunteers: 400 mg theophylline was given intravenously and in two different forms into the colon transversum by application with an endoscope. Under these conditions, theophylline was absorbed in an amount of 54% on the average with some variation due to the applied formulation. Therefore, it could be concluded that theophylline is absorbed to a clinically relevant extent from the large intestine. These results are remarkable with regard to the development and pharmaceutical profiles of retard or slow-release formulations of theophylline and the undesired effects of this therapy.

Outlook 2000. The major trends.

The American economy is expected to grow by 30 percent between 1988 and 2000, while the labor force will increase by 16 percent. This summary of trends for the economy, the labor force, industries, and occupations also looks at some implications of the projections. For example, continued growth opens the way to a more equitable labor market in the future, but only if workers have the education and training needed by employers.