EVALUATION OF 2 FORMS OF SUSTAINED-RELEASE NIFEDIPINE USING 24 H AMBULATORY BLOOD-PRESSURE MONITORING

Therapeutic interchange between the available forms of sustained relea se nifedipine (osmotic-pump and coat-core forms of nifedipine) is a ma tter of controversy. This study was initiated to determine whether the re is a difference in clinical outcomes when there is interchange betw een the two forms of sustained release nifedipine when used for the tr eatment of hypertension. A total of 43 patients with a history of stag e I hypertension who were receiving stable doses of the osmotic-pump f orm of nifedipine for > 3 months with controlled blood pressures (< 15 0/90 mm Hg) were enrolled. Patients were then switched to the same dos e of the coat-core form of nifedipine and were followed for 3 months. In the 36 patients who completed the study, mean trough serum nifedipi ne concentrations were significantly higher with the osmotic-pump from (46.5 +/- 35.0 ng/mL) of nifedipine compared with the coat-core form (27.2 +/- 20.4 ng/mL) (P <.05). However, blood pressure control as det ermined by the indices of 24 h ambulatory blood pressure monitoring, t rough blood pressures and load blood pressures were similar between th e osmotic-pump and coat-core forms of nifedipine. The coat-core form o f nifedipine was discontinued in four patients for possible side effec ts. In this group of patients with mild hypertension, there were no cl inically relevant differences in blood pressure control between the tw o forms of nifedipine. Some patients on the coat-core form of nifedipi ne may need to discontinue therapy due to intolerable side effects. (C ) 1997 American Journal of Hypertension, Ltd.