Nifedipine gastrointestinal therapeutic system (GITS) as an alternative to slow-release for tocolysis—Tolerance and pharmacokinetic profile

ObjectiveTo determine nifedipine plasma concentrations after a loading dose of nifedipine 10 mg capsules, 40 mg over 1 h followed by slow-release tablets (60 mg/d) versus gastrointestinal therapeutic system (GITS) tablets (90 mg/d) for tocolysis.Study designProspective study in 14 pregnant women treated for threatened preterm labor.ResultsFollowing capsule administration there was a rapid rise in plasma concentration of drug achieving a peak of 97.5 μg/l (median) at 1 h, then declined to 59.5 μg/l (median) at 5 h. The concentration measured at 7200 min (120 h) was non-significantly higher in the slow-release group (median 25.5, range 6.9–67.2 μg/l) than in the GITS group (median 14.6, range 6.0–20.0 μg/l). Area under the curve (AUC) increased with the applied dose in both groups in a linear regression. Headache was more frequent in the slow-release group than in the GITS group (P = 0.001).ConclusionsGITS tablets 90 mg/d are an alternative dosage regimen to previous used slow-release tablets 60 mg/d for tocolysis with similar pharmacokinetic profile and a good tolerance. However, tocolysis with GITS tablets is simpler than that with slow-release tablets and may be associated with a higher compliance. GITS tablets are therefore also qualified for home monitoring.