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P A R T 8  Drugs acting on the cardiovascular system

TABLE 43.2

DRUGS IN FOCUS Antihypertensive agents (continued)

Drug name

Dosage/route

Usual indications

Calcium channel blockers (continued) lercanidipine (Lercan, Zanidip, Zircol)

10–20 mg/day PO

Used alone or in combination with other agents for treatment of hypertension in adults Extended-release preparations only for the treatment of hypertension in adults; other preparations are used for angina Extended-release formulations for the treatment of essential hypertension; other preparations are used for angina and treating various arrhythmias in adults

nifedipine (Adalat, Adefin, Nyefax)

30–60 mg/day PO

verapamil (Anpec, Cordilox SR, Isoptin)

120–240 mg/day PO, reduce dose in the morning; extended release capsules: 100–300 mg/day PO at bedtime

Vasodilators diazoxide (generic)

1–3 mg/kg IV, by rapid bolus over 30 seconds; may be repeated q 5–15 minutes as needed 5–10 mg by slow IV, or continuous infusion 200–300 mcg/minutes Paediatric: 1.7–3.5 mg/kg per 24 hours IV or IM in four to six divided doses Adult: 10–40 mg/day PO in divided doses Paediatric (<12 years): 0.25–1 mg/kg per day PO as a single dose Adult and paediatric: 3 mcg/kg per minute, do not exceed 10 mcg/kg per minute

Treatment of severe hypertension in hospitalised adults Treatment of severe hypertension

hydralazine (Alphapress, Apresoline)

minoxidil (Loniten)

Treatment of severe hypertension unresponsive to other therapy

Treatment of hypertensive crisis; also used to maintain controlled hypotension during surgery

sodium nitroprusside (generic)

Other antihypertensive agents Diuretic agents See Chapter 51

See Chapter 51

Treatment of mild hypertension; often first agents used; often used in combination with other agents

Sympathetic nervous system blockers See Chapter 31

See Chapter 31

Drug therapy across the lifespan

BOX 43.4

Drugs affecting blood pressure CHILDREN

levels on a regular basis. Beta-blockers have been used with success in some children; adverse effects may limit their usefulness in others.The safety and efficacy of the angiotensin-converting-enzyme (ACE) inhibitors and the angiotensin-receptor blockers (ARBs) have not been established in children. Calcium channel blockers have been used to treat hypertension in children and may be a first consideration if drug therapy is needed. Careful follow-up of the growing child is essential to monitor for changes in blood pressure, as well as for adverse effects. ADULTS Adults receiving any of these drugs need to be instructed about adverse reactions that should be reported immediately.They need to be reminded of safety precautions that may be needed in hot weather or with conditions that cause fluid depletion (e.g. diarrhoea, vomiting). If they are taking any other drugs, the interacting effects of the various drugs should be

National standards for determining normal levels of blood pressure in children are quite new. It has been determined that hypertension may start as a childhood disease, and more screening studies are being done to establish normal values for each age group. Children are thought to be more likely to have secondary hypertension, caused by renal disease or congenital problems such as coarctation of the aorta. Treatment of childhood hypertension should be done very cautiously because the long-term effects of the antihypertensive agents are not known. Lifestyle changes should be instituted before drug therapy if at all possible. Weight loss and increased activity may bring an elevated blood pressure back to normal in many children. If drug therapy is used, a mild diuretic may be tried first, with monitoring of blood glucose and electrolyte