Bioavailability of Aminophylline Tablet and Suppository

The bioavailability of aminophylline was investigated by comparing the areas under concentration-time curves for intravenous aminophylline with a plain uncoated aminophylline tablet and an aminophylline suppository. Six healthy adult volunteers received 250 mg aminophylline intravenously, 300 mg orally and 600 mg rectally, according to the three-way crossover method. Serum theophylline concentration was measured for at least 30 hours by high-performance liquid chromatography. The fraction of the dose absorbed averaged 0.91±0.10 for the tablet while the value for the suppository was 0.73±0.11. The maximum serum concentration converted in terms of 250 mg aminophylline was 7.76±0.92 μg/ml for the tablet and 4.79±0.49 μg/ml for the suppository. Peak serum concentration time averaged 2.0±0.4 hr for the tablet and 4.9±0.5 hr for the suppository. These results demonstrate that absorption from these dosage forms was reliable and that the aminophylline tablet and suppository may be efficacious clinically. Dosage regimens of the aminophylline tablet and suppository calculated from the above data are presented.