McKenna's Drug Handbook for Nursing & Midwifery, 7e

14      General information

Be sure to observe the individual for signs or symptoms of toxicity. A person receiv- ing digoxin, for example, may experience anorexia, nausea, vomiting or confusion. Adverse drug reactions Compared with younger people, older adults experience twice as many adverse drug reactions because of multiple-drug therapy, poor compliance and physiologi- cal changes. Signs and symptoms of adverse drug reactions—confusion, weakness and lethargy—are commonlymistaken for senil- ity or indications of disease. If the adverse reaction is not identified, the person may continue to receive the drug. Furthermore, the person may receive unnecessary addi- tional medication to treat complications caused by the original medication. This may lead to a pattern of inappropriate and excessive medication use. Although any medication can cause adverse reactions, themost serious reactions in the older adult are causedby relatively few medications.Beparticularlyalertfortoxicities resulting from diuretics, antihypertensives, digoxin, corticosteroids, anticoagulants, sleeping aids and nonprescription drugs. Diuretic toxicity Because total body water content decreases with age, normal dosages of potassium- wasting diuretics, such as hydrochlorothia- zide and frusemide, may result in fluid loss and even dehydration in an older person. These diuretics may deplete serum potas- sium, causing weakness, and may elevate blood uric acid and glucose levels, com- plicating pre-existing gout and diabetes mellitus. Antihypertensive toxicity Many older adults experience light- headedness or fainting when using antihy- pertensive medications, partly in response to atherosclerosis and decreased elasticity of blood vessels. Antihypertensive drugs may reduce blood pressure too rapidly, resulting in dizziness or fainting.

Consequently, dosages of antihyperten- sive drugs must be carefully individualised. In older adults, overly aggressive treatment of high blood pressure may do more harm thangood, so treatment goals shouldbe rea- sonable. Although bringing blood pressure down to 120/85 mmHg may be appropri- ate in a young hypertensive person, a more reasonable goal for an older hypertensive person might be 150/95 mmHg. Digoxin toxicity As the body’s renal function and excretion rate decline, digoxin concentrations in the blood may build to toxic levels, causing nausea, vomiting, diarrhoea and—most seriously—cardiac arrhythmias. Try to pre- vent severe toxicity by monitoring serum drug levels and by observing the person for early signs or symptoms, such as appetite loss or visual disturbances. Corticosteroid toxicity Older adults on corticosteroids may expe- rience short-term effects, including fluid retention and psychological manifestations ranging from mild euphoria to acute psy- chotic reactions. Long-term toxic effects, such as osteoporosis, can be especially severe in older adults who have been taking prednisone or related steroidal compounds for months or even years. To prevent seri- ous toxicity, carefully monitor individuals on long-term regimens. Observe them for subtle changes in appearance, mood and mobility; signs of impaired healing; and fluid and electrolyte disturbances. Anticoagulant effects Older adults taking anticoagulants have an increased risk of bleeding, especially when they take NSAIDs concomitantly (as many do). Observe the INR carefully, and monitor the person for bruising and other signs of bleeding. Sleeping-aid toxicity Sedatives or sleeping aids, such as nitraz- epam, may cause excessive sedation or