[Oral tocolytic therapy with clenbuterol--determination of the plasma level].

12 pregnant women with premature labor received tocolytic treatment with clenbuterol tablets. Initially, 2 clenbuterol tablets (40 micrograms each) were to be given as loading dose (application interval = 12 hours), then a dose reduction was planned (40 micrograms), to be followed by a maintenance dose of 20 micrograms. The mean values of plasma levels of clenbuterol hydrochloride during the day ranged between 0.266 and 0.328 ng/ml on testing days 2 to 8, without significant statistical variation. Therefore, the loading dose lead to the desired rapid steady state of the plasma level. The applied dosage plan with clenbuterol tablets for oral therapy of premature labor proved to be ideal, both clinically as well as pharmacokinetically. After reaching an effective plasma level, only 20 micrograms b.i.d. is sufficient as maintenance dose, resulting in excellent patient compliance compared with oral fenoterol therapy (max. application interval: 4 hours).