Plasma concentrations of theophylline and quinine in healthy volunteers following oral administration of a fixed drug combination.

Theophylline and quinine plasma concentrations were determined in 4 healthy volunteers following oral administration of two tablets of Limptar . According to the recommended dose schedule the second tablet was administered 3 h after the first tablet. Peak concentrations of theophylline and quinine in the plasma were observed at 5.4 h (theophylline) and 5.1 h (quinine), respectively, following administration of the first tablet. Half-life of theophylline ranged from 7.2 to 15.4 h (9.4 +/- 4.4 h; mean +/- SD) and that of quinine from 5.4 to 27.2 h (14.4 +/- 9.2 h). Peak concentrations of theophylline in the plasma (7.5 +/- 1.6 micrograms/ml) are below those which are thought to produce concentration-dependent side effects. Besides the superior therapeutic efficacy of the combination of quinine and theophylline compared to that of quinine alone, this combination seems to be favourable also from a pharmacokinetic point of view.