TAKE STEPS TO GET BLOOD PRESSURE DOWN! New Guidelines on Hypertension from a Co-operative Study in the US

This reiJort of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure is a consensus ofthe organisational representatives serving on the committee.

Six general recommendations are given: • Any group measuring BP should have referral, confirmation and follow-up resources available. • All patien~ with a diastolic BP of \ OSmm Hg or more should be treated with antihypertensive drugs. • If the diastolic pressure is 90-\ 04mm Hg, tr~tment should be individualised, with consideration given to risk factors. • A few baseline tests are usually.~ufficient for evaluating patients with high BP. • A 'stepped-care' approach is advocated as a cost-effective method oftreating most patients, without compromising quality

care. • Treating high BP includes plans for long-term BP control.

What do they say about drug treatment? Therapy should aim at diastolic pressures of less than 90mm Hg with minimal adverse effects. This is possible in 80-85 % of patients. Drug treatment may be indicated in patients with diastolic BPs of 90-1 05mm Hg by the following factors: elevated systolic BP, target organ damage, family history of hypertension complications, male sex, smoking, elevated blood cholesterol, or diabetes.

Guidelines for stepped care Therapy should start with a small dose of an antihypertensive drug, increasing the dose, and then 'adding, one after another, other drugs as necess~ry. Peri<;>dic re~evalu.ation and stepping down the dosage when possible is desirable. Patients with diastolic pressures belo)\' J 05mm Hg, if treated with drugs, should be given thiazide diuretics, and those.with·diastolic BPs above 130mm Hg require intepsive therapy with s~veral drugs simultaneously. For accelerated high BP parenteral sodium nitroprusside ('Nipride') or diazoxide ('Hyperstat') may be necessary. For the large group in the middle (diastolic-BP: 1 05-129mm Hg), the stepped care programme is usually suitable, remembering that no one combination of drugs' works for all patients. These are the steps to take:

• Start with a low dose of a tb~azide diuretic. If potassium levels fall, potassium suppleqtents or a potassium-sparing diuretic - spironolactone or triamterene ('Dyrenium') - may be added. Special care is necessary to avoid toxicity with digitalis imd a diuretic.

G) If BP is still high, a second drug should \;le added, such as reserpine, qlethyldopa (' Aldomef) or· propranolol. Reserpine is inexpensive and may' be taken once daily, but it may cause depression, lethargy and p~r conCentration. Side-effects of· methyldopa are drowsiness, fatigue and impotence; and propranolol may cause fatigue or insomnia, or may precipitate asthma or aggravate heart failur~.

• The third step is acldition of hydrallazine hydrochloride. Caution is urged in patients with angina. • Ifthese steps are ineffective it is time to add guanethidine. Higher doses may, cause postural dizziness, diarrhoea or

ejaculatory impotence, but guanethidine is potent and often effective in resistant cases.

Clonidine hydrochloride ('Catapres') and prazosin hydrochloride ('Minipress') may be substituted for a step 2 drug. Dry mouth and drowsiness are common' si~e-effectsof clonidine, and prazosin may cause sudden Collapse, postural dizziness, weakness and dizziness. Different variations of combinations should be tried until a suitable one is found. To simplify the regimen after BP has reached goa) level, it is reasonable to swi~ch to combination therapy (2 or more drugs in 1 pill), if the right combination is available .. For patients atthe hig~er end of the. BP range in this group,treatment may start with a full dose instead ofa half dose of a thiazide, and intervals between changes in the regimen and maximum dosages should be increased. Withdrawal of antihypertensive drugs prior to surgery is usually unnecessary, provided that the anaesthetist knows the patient's medication, and pre- and postoperative potassium levels are determined. A Co-operative Study: Journal of the American Medical Association 237: iss (17 Jan) 977)

... This Report is a.Useful Guide. Nota Rigid Directive! Whiie all physicians should give careful attention to this report, it should be remembered that such reports are compromises. statements by committees are oft;en given more authority than. they deserve. 'Certainly, they should not become instruments that block fur~her.experimen(ation and innovation in the management of a disease, 'warns this writer. General guides for management may not apply to an individual any more than statistics do.

Thus, a physician ''Just employ his own professionaljudgment tempered by experience and by recommendations such as those in the report of the Joint National Committee .. Good medical treatment is the result of a meticulously constructed dala base, a thoughtfully considered diagnosis oj the problem, and the.exercise of experience and common sense in prescr:ibin¥ therapy.

Barclay. W.R.: Ibid 237: 267 (I] Jan 1977)

lNPHARMA 5th February, 1977 p11