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C H A P T E R 4 3 Drugs affecting blood pressure

Drug therapy across the lifespan (continued)

BOX 43.4

evaluated.The importance of other measures to help lower blood pressure—weight loss, smoking cessation, increased activity—should be stressed. PREGNANCY AND BREASTFEEDING The safety for the use of these drugs during pregnancy has not been established. ACE inhibitors, ARBs and renin inhibitors should not be used during pregnancy. Women of childbearing age should be advised to use barrier contraceptives to prevent pregnancy while taking these drugs. Calcium channel blockers and vasodilators should not be used in pregnancy unless the benefit to the mother clearly outweighs the potential risk to the fetus.The drugs do enter breast milk and can cause serious adverse effects in the baby. Caution should be used or another method of feeding the baby should be used if one of these drugs is needed during breastfeeding. OLDER ADULTS Older adults frequently are prescribed one of these drugs. They are more susceptible to the toxic effects of the drugs and are more likely to have underlying conditions

that could interfere with drug metabolism and excretion. Renal or hepatic impairment can lead to accumulation of the drugs in the body. If renal or hepatic dysfunction is present, the dose should be reduced and the person monitored very closely. The total drug regimen of the older person should be coordinated, with careful attention to interactions among drugs and alternative therapies. Older adults need to use special caution in any situation that could lead to a fall in blood pressure, such as loss of fluids from diarrhoea or vomiting, lack of fluid intake, or excessive heat with decreased sweating that comes with age. Dizziness, falls or syncope can occur if the blood pressure falls too far in these situations.The blood pressure should always be taken immediately before an antihypertensive is administered to an older adult in an institutional setting to avoid excessive lowering of blood pressure. Older people should be especially cautioned about sustained-release antihypertensives that cannot be cut, crushed or chewed to avoid the potential for excessive dosing if these drugs are inappropriately cut.

FIRST CHOICE

ACE inhibitor (or angiotensin II receptor antagonist) or calcium channel blocker, or low-dose thiazide diuretic (consider for people aged ≥ 65 years only)

IF TARGET BP NOT REACHED

ACE inhibitor (or angiotensin II receptor antagonist) + calcium channel blocker

ACE inhibitor (or angiotensin II receptor antagonist) + low-dose thiazide diuretic

or

IF TARGET BP NOT REACHED

IF TARGET BP NOT REACHED

ACE inhibitor (or angiotensin II receptor antagonist) + calcium channel blocker + low-dose thiazide diuretic

Consider seeking specialist advice

FIGURE 43.4  Algorithm for the treatment of hypertension. Source: Heart Foundation (2010). In Guide to Management of Hypertension: Assessing and Managing Raised Blood Pressure in Adults, p. vi. Available at: www.heartfoundation.org.au/SiteCollectionDocuments/ HypertensionGuidelines2008to2010Update.pdf.