CONVERSION FROM SUSTAINED-RELEASE TO IMMEDIATE-RELEASE CALCIUM-ENTRY BLOCKERS - OUTCOME IN PATIENTS WITH MILD-TO-MODERATE HYPERTENSION

We evaluated 110 patients with mild-to-moderate hypertension (diastoli c blood pressure 95 to 110 mmHg) whose blood pressure was initially co ntrolled on monotherapy with once-daily sustained-release calcium entr y blockers; these patients were then switched to their respective imme diate-release formulations TID. The study group consisted of 35 patien ts on diltiazem controlled delivery (CD) switched to immediate-release diltiazem, 41 patients on nifedipine gastrointestinal therapeutic sys tem (GITS) switched to immediate-release nifedipine, and 34 patients o n verapamil sustained-release (SR) switched to immediate-release verap amil. Outcome evaluation included a pair-wise comparison of the follow ing during treatment with both formulations: blood pressure control, n eed for additional hypertensive agents, side effects, compliance, and cost of therapy. Blood pressure was controlled in 94% of pa-tients swi tched from diltiazem CD to immediate-release diltiazem; 6% of patients required additional antihypertensive agents. Side effects and complia nce were not significantly different between groups. Blood pressure wa s controlled in 78% of patients switched from nifedipine GITS to immed iate-release nifedipine; 22% of patients required additional antihyper tensive agents. Side effects, compliance, and cost of therapy were sig nificantly different between groups. Side effects increased from 32% o n nifedipine GITS to 58% on immediate-release nifedipine; and complian ce decreased from 93% on nifedipine GITS to 76% on immediate-release n ifedipine (P<0.05). Blood pressure was controlled in 91% of patients s witched from verapamil SR to verapamil immediate release; 9% of patien ts required additional antihypertensive agents. Side effects and compl iance were not significantly different between groups, but immediate-r elease verapamil was significantly less expensive than verapamil SR, C onversion from sustained-release calcium entry blockers to immediate-r elease calcium entry blockers is cost-effective for verapamil and dilt iazem, but not for nifedipine.