Comparative efficacy of two long-acting formulations of nifedipine in the treatment of hypertension. The Switch Study Investigators.
OBJECTIVE
To compare the antihypertensive effects and incidence of side effects of two formulations of nifedipine: a prolonged action (PA) tablet bid and a gastrointestinal therapeutic system (GITS) tablet once daily.


METHODS
Patients with controlled hypertension (diastolic blood pressure less than 90 mmHg) on nifedipine-PA 10 mg (n = 74) or 20 mg (n = 99) bid were enrolled into an open label study consisting of six weeks of previous nifedipine-PA followed by six weeks of nifedipine-GITS therapy. Nifedipine-GITS was increased from 30 mg to 60 mg daily if the patient's diastolic blood pressure increased by at least 10 mmHg compared with the value after six weeks of nifedipine-PA.


RESULTS
Blood pressure after six weeks of nifedipine-PA 10 mg (142 +/- 1/86 +/- 1 mmHg) decreased (P < 0.01) after conversion to nifedipine-GITS 30 mg (137 +/- 1/84 +/- 1 mmHg). Blood pressure values for nifedipine-PA 20 mg patients were unchanged after conversion to nifedipine-GITS; 74 patients received nifedipine-GITS 30 mg and 14 patients required titration up to nifedipine-GITS 60 mg daily. Sixteen patients withdrew on nifedipine-PA and five withdrew on nifedipine-GITS, mostly for reasons unrelated to drug therapy. Twenty-three patients experienced adverse events on nifedipine-PA versus 20 patients on nifedipine-GITS therapy.


CONCLUSIONS
Patients whose hypertension is controlled by nifedipine-PA 10 or 20 mg bid can be successfully converted to nifedipine-GITS with most patients remaining normotensive on 30 mg daily.
D000293:Adolescent; D000328:Adult; D000368:Aged; D003692:Delayed-Action Preparations; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000008:administration & dosage* / Q000009:adverse effects; D010349:Patient Compliance; D013607:Tablets
D003692:Delayed-Action Preparations; D013607:Tablets; D009543:Nifedipine