VASODILATORS FOR ANGINA PECTORIS

Nitrates: Sublingual gfyeeryl IrinilrQ/e(nitrvglycerin)is still the best drug for preventing single attacks of angina pectoris, because of its rapid, brief action. It remains effective with repeated use during the day and can also be used for prolonged attacks. The occa.~ional patient who has no benefit or side effects with O.Smg should try double tbis dose before the drug is judged ineffective. Because afthe shen shelf-life of glyceryl trinitrale, the patient's stock should be renewed if tablets cease to be effective. The tendency for this drug to cause headache can be reduced by taking only half a tablet, or the smallest amount that relieves angina and discarding the rest. A ~-blocker is the first choiae for continuous prophylaxis of angina. Use of orallong-ucflng ni/rales as prophylaxis is still controversial, but recent weU designed studies have shown sustained action and long term benefit. They may be particularly useful combi ned with a ~-blocker . Sublingual iSl)sorbide dinilrale has given disappointing results. Glyceryl trinitrale

Ointment. which is widely used in the US, is effective for at least 2·3 hours. bul is inconvenient to use. Calcium antagoniS18 are particularly useful in variant(Prinzmetal's)angina, but are also valuable in angina associated with

coronary arterial atheroma. particularly where ~-blockers are contraindicated. Ni/edipille is an oral long-acting drug which blocks calcium influx into both cardiac and vascular smooth muscle. mainly dilating resistan~ vessels. In some patients it can increase angina. It may be combined cautiously with a ~·b1ocker like propranolol. Nifedipine has no advantage over a ~·blocker + a nitrate, but may suit patients intolerant of these drugs. When pain is difficult to control. nifedipine may ~ added to the ~blocker + nitrate combination. Verapamil affects calcium influx into the AV node relatively more than into cardiac muscle or peripheral

blood vessels. It is therefore particularly useful for treating supraventricular tachyarrhythmias, but can also be beneficial in angina of effort and variant angina. 360mg/day in 3 divided doses has proved lIseful . Verapamil should not be used by patients with first

or second degree heart block and is relatively oontraindicated for use with ~·blocker$ . Drul ilnd Tlw:npcutics. Bulletin 19: 31 (8 May t 98 1)

0156·2103/ 81 / 0530·0003 $00.50/ 0 C ADIS Press INf'HARMAJOMilV 1981 3