[A comparative study of the pharmacokinetics of oral preparations of theophylline]

The pharmacokinetics of five preparations of theophylline--euphylline and sustained-release forms (theo-dura, retaphylline, theopac and theobilong) was studied in 50 patients with the broncho-obstructive syndrome. Blood serum theophylline concentration was determined by high performance liquid chromatography. The main differences in the pharmacokinetic parameters manifested themselves in the period of half-absorption--the least one for euphylline and the greatest one for theopac. A close correlation between blood serum theophylline concentration and the profile of theophylline release from theopac tablets was revealed. The equal theophylline concentration in blood serum was determined on the 4th and 7th days of the course treatment with sustained-release preparations administered twice a day, the concentration values ranged within the subtherapeutic level. An increase of the dose by 50-150 mg/day resulted in an increase of blood serum theophylline concentration within the therapeutic range.