[The bioavailability of 4 sustained-release theophylline preparations from the Chilean market].

We evaluated pharmacokinetic parameters and bioavailability of 4 sustained release theophylline preparations. A crossover design was used in 12 healthy males aged 22 to 27 years old. Each individual received 250 mg iv followed by 250 mg orally of each preparation, and then 400 mg rapid acting aminophylline. A 7 day period was allowed between drug courses. HPLC was used to determine plasma levels of theophylline at regular intervals up to 48 hr following drug administration. Significant (p < 0.05) differences in pharmacokinetic parameters were found among preparations, 2 of them having larger integrals of plasma levels and one of them different times to peak plasma level and peak plasma concentration, compared to both remaining preparations.