Original Articles: PDF OnlyImproved Efficacy and Safety of Controlled-Release Diltiazem Compared to Nifedipine May Be Related to Its Negative Chronotropic EffectBasu, Sumit K.1; Kinsey, Christopher D.1; Miller, Alan J.2; Lahiri, Avijit1*Author Information 1Department of Cardiac Research, Northwick Park Hospital and Institute for Medical Research, Harrow, Middlesex; and 2Napp Laboratories, Cambridge, United Kingdom. Funded in part by a grant from Napp Laboratories (Cambridge, UK) and by the Northwick Park Hospital Cardiac Research Fund. *Address for correspondence: Cardiology Department, Northwick Park Hospital, Watford Road, harrow, Middlesex, HA1 3UJ, UK. American Journal of Therapeutics: January 2000 - Volume 7 - Issue 1 - p 17-22 Buy Abstract The objective of this study was to assess the safety and efficacy of long-acting preparations of two commonly used calcium antagonists with particular reference to their effects on heart rate. Twenty patients with chronic stable angina were recruited to a double-blind, double-dummy crossover study of controlled-release diltiazem (diltiazem CR) versus sustained-release nifedipine (nifedipine SR) and underwent clinical assessment, symptom and adverse event reporting, and repeated treadmill exercise tests over a 10- to 11-week period. The main outcome measures were heart rate at rest and exercise, incidence of angina and nitroglycerin use, treadmill exercise performance (duration, time to angina, time to 1-mm ST-segment depression, heart rate at equivalent maximal exercise, and maximal ST-segment depression), and adverse events. Diltiazem CR significantly reduced heart rate at rest and equivalent exercise and incidence of angina and nitroglycerin use compared with nifedipine SR. Exercise duration time to angina and time to 1-mm ST-segment depression (but not maximal ST-segment depression) were all significantly improved by diltiazem CR. Diltiazem CR also caused significantly fewer adverse events than nifedipine SR. Calcium antagonists with negative chronotropic effects (eg, diltiazem CR) are safer and more efficacious as monotherapy in chronic stable angina than dihydropyridines (eg, nifedipine SR) even when a long-acting formulation of the latter is used. © 2000 Lippincott Williams & Wilkins, Inc.