The pharmacokinetics of caffeine are greatly altered by concomitant administration of idrocilamide. In four healthy volunteers id rocilamide inhibited the biotransformation of caffeine and increased its half-life nine times. The untoward neuropsychiatric effects of idrocilamide are the consequence of abnormal accumulation of caffeine in regular consumers of caffeine-containing foods and beverages.
The acute effects of a single dose of diltiazem (Tildiem), a calcium antagonist, were studied in 9 patients with severely impaired renal function (GFR between 0.03 and 0.87 ml/s/1.73 m2). Control measurements were made of inulin and PAH clearance, creatinine, blood pressure, heart rate and ECG. Following administration of diltiazem 120 mg, 7 blood samples were collected in the first 12 h and after 24 h, 32 h, 48 h; urine was collected for the first 12 h, 12-24 h and 24-48 h, and blood pressure, heart rate and ECG were recorded after 6 h. Diltiazem and its main metabolite, desacetyldiltiazem, had a pharmacokinetic profile similar to that in patients with normal renal function (peak plasma concentration, half-life and urinary excretion). Diltiazem is normally eliminated in the urine to a small extent, because it is metabolized, and this also applies to desacetyldiltiazem, which is probably further metabolized.
We studied the metabolism of theophylline in premature neonates by the use
of molecules labelled with stable isotopes. 2 prematures received from birth up to 8th day
of life 3 mg/kg/8 h of a mixed solution containing 46% of labelled and 54% of unlabelled
theophylline. Plasma levels of caffeine and theophylline, measured by gas chromatographicmass
spectrometric analysis, demonstrated the in vivo biotransformation of theophylline to
caffeine in prematures.
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