High-performance liquid chromatography determination of pravastatin in plasma.

Pravastatin is a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor that reduces plasma cholesterol levels. Some analytical methods have been described for determination of pravastatin levels in biological fluids, but these methods are rather cumbersome and involve expensive specialized equipment, usually not available in a clinical setting. A new technique, reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection capability, has been developed for the analytical determination of pravastatin in plasma. Extraction and sample clean-up procedures are simple and rapid to execute, yet yield chromatograms virtually free of interference from endogenous plasma constituents and other antihypercholesterolemic agents or drugs usually taken concomitantly with pravastatin. Our detection limit for pravastatin was 2 ng/ml. Standard curves were linear between 5 and 200 ng/ml, with a coefficient of variation (CV) of < 10% at the limits of quantitation. This method was used to study pravastatin plasma levels in two hypercholesterolemic heart-transplant recipients and two hypercholesterolemic nontransplanted patients. We conclude that the method reported here would be ideal for therapeutic pravastatin monitoring in patients.

[Bioavailability of a delayed-action aminophylline preparation]. / Biodisponibilità di un preparato ritardo di aminofillina.

Absorption of theophylline from one commercial product labelled as aminophylline sustained release was compared to the absorption from an oral solution of aminophylline in a single-dose bioavailability study. Aminomal-R tablets had bioavailability (101.2 +/- 19) statistically indistinguishable from that of the standard but showed significantly slower absorption (peak times of 3.6 +/- 1.1 h vs 1.3 +/- 0.8 h) and lower peak plasma concentrations (16.8 +/- 4.7 mg/l/1 g aminoph. dose vs 21.1 +/- 4.2 mg/l/1 g aminoph. dose). Projections of plasma concentrations upon multiple dosing were made from single dose data: the dosage interval (every 12 h) concentration ratio which reflects both the frequency of dosing and the entry of the drug into and removal from the body was of 1.8 vs 3.1.

The clinical pharmacology of drug interactions.

Preliminary evaluation of pre-established and extemporaneous combinations showed that any combination requires broad, precise, and scientifically valid documentation. Every drug has to be evaluated according to physical, chemical, and pharmacologic points of view, either individually or in combination, and above all be adapted to the individual needs of each patient. To make a realistic contribution to evaluating and devising new combinations, specialized centers should be instituted such as the Central Admixture Service of S. Matteo Hospital in Pavia.