A COMPARATIVE-STUDY OF LONG-ACTING DILTIAZEM (TILDIEM LA) WITH SUSTAINED-RELEASE NIFEDIPINE (NIFEDIPINE SR) AND BENDROFLUAZIDE IN THE TREATMENT OF MILD-TO-MODERATE HYPERTENSION

The therapeutic efficacy of long acting diltiazem 300 mg od (Tildiem L A) was compared with sustained release nifedipine 20 mg bd and bendrof luazide 5 mg od in a multicentre study with 230 patients diagnosed wit h mild to moderate essential hypertension, with 77, 77 and 76 randomiz ed to the diltiazem, nifedipine SR and bendrofluazide groups respectiv ely. Patients were entered into this randomised, single (investigator) blind, parallel-group multicentre study if the systolic and diastolic blood pressures were greater-than-or-equal-to 145 mm Hg and/or 95 mm Hg respectively at the admission visit. Twenty-one general practitione rs and two hospital physicians monitored patients at baseline and at f our and eight weeks of continuous dosing. After eight weeks of therapy , clinically acceptable control of blood pressure was seen in all grou ps: reductions were 19.2/13.5 mm Hg, 20.4/14 mm Hg and 18.5/10.8 mm Hg for the Tildiem, nifedipine and bendrofluazide groups respectively. S ignificant differences were shown between bendrofluazide and the other two groups on diastolic pressures (p = 0.01). The non-significant tre nd was for systolic pressures to mirror these effects. Significantly h igher withdrawals caused by adverse events were seen with nifedipine. These were as follows: 14 patients receiving nifedipine (18%), 5 patie nts receiving diltiazem (6%) and 4 patients receiving bendrofluazide ( 5%). The difference in this withdrawal rate between treatments was sta tistically significant (p = 0.01). Post hoc tests revealed that both d iltiazem and bendrofluazide had statistically significant lower withdr awals for adverse events than the nifedipine group (p = 0.047). Nifedi pine was associated with a marginal increase in standing apex pulse ra te and only diltiazem LA significantly maintained serum potassium leve ls. These results indicate that diltiazem 300 mg is an effective antih ypertensive agent and is equivalent in efficacy to nifedipine SR 20 mg and both are superior to bendrofluazide. Nifedipine SR was however th e worst tolerated and had the highest withdrawal rate (p = 0.013).