WHEN CHOOSING ANTIHYPERTENSIVE AGENTS -

... How Important Are Their Other Biochemical Effects? While debate over treatments for hypertension has largely centred on the BP level at which treatment should start and how much BP should be reduced, it is now lime to look al the other effoclS of the various drugs as well as their antihypertensive effects. Thiazide diuretics are cheaper than jl·blockers but it is still not known exactly how they work and they have several biochemical effects of unknown long term importance. Some hypokalaemia is almost inevitable. but not harmful in otherwise fit patients. Thiazides also impair carbohydrate tolerance in some patients and increase plasma renin concentrations. It has been suggested thaI hypertensive patients with normal and high renin levels have a greater risk ofstroke and heart attack than 'low renin' hyper-tensives. If so, trealmentthat lowers plasma renin - such as ~-blockade - should be more beneficial than equally effective antihypertensive

treatment that increases plasma renin -such as diuretics and peripheral vasodilators. This is still debatable. but 2 studies have shown different results using different antihypertensive agents. The Veterans Administration studies showed a significant reduction in stroke and heart failure. but none in myocardial infarct)on, with a combination of reserpine (centrally actin ). h~dr.~l!azine and hyd(~hlorothiazide (both potent stimulatOrs of renin release). The Gothenburg group, using a ~-bIOCk!r plus a thUlZlde and hydrallazl ne where necessary, found a reduction in death from coronary heart disease and in incidence of myocardial infarction but no reduction in fatal and non-fatal strokes. Do the different outcomes refleclthe differem treatments used or the types of patients treated'! This will nol be known until the finish of prospective randomisoo studies to compare the outcome in patients being treated with either a diuretic Of a ~·blocker.

'In the meantime t here seems no compelling feason to ignore the cheaper and well -tested thiazide diuretics in favour of the more costly bota-blockers in those patients with essential hypertension for whom treatment with a single agent is sufficient . '

[ditQria/: British Mecliod Journal 2, 7S (8 JUl19181

INPHARMA 22nd July. 1978 p3