The pharmacokinetics of bamifylline (Briofil) has been studied in 6 healthy volunteers both after acute and chronic administration. The kinetic variables were similar both after the first dose and after chronic treatment and no significant accumulation of the drug was observed after 7 days of therapy with bamifylline (600 mg b.i.d.). The analysis of minimal concentrations of bamifylline did not yield evidence of circadian variation in the kinetics of this drug; large differences among subjects and within each subject on different days may be explained by changes in drug bioavailability. Very low plasma levels of bamifylline were observed at the end of the dosing intervals in 50% of the cases; this observation does not necessarily invalidate the efficacy of this dosage regimen because the active metabolite of bamifylline (AC119) might contribute to the bronchodilator activity of this drug.