McKenna's Pharmacology for Nursing, 2e

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P A R T 8  Drugs acting on the cardiovascular system

on a calcium channel blocker reports toxic effects, ask whether they are drinking grapefruit juice and if so advise them to cease drinking the juice.

Prototype summary: Diltiazem Indications: Treatment of essential hypertension in the extended-release form. Actions: Inhibits the movement of calcium ions across the membranes of cardiac and arterial muscle cells, depressing the impulse and leading to slowed conduction, decreased myocardial contractility and dilation of arterioles, which lowers blood pressure and decreases myocardial oxygen consumption. Pharmacokinetics: Route Onset Peak Duration Oral, ext release 30–60 mins 6–11 hours 12 hours T 1/2 : 5–7 hours; metabolised in the liver and excreted in urine.

Care considerations for people receiving calcium channel blockers The main use of calcium channel blockers is for the treatment of angina. See Chapter 46 for the care considerations of calcium channel blockers. See the Critical thinking scenario for the initiation of antihypertensive therapy using calcium channel blockers .

Adverse effects: Dizziness, light-headedness, headache, peripheral oedema, bradycardia, atrioventricular block, flushing, nausea.

CRITICAL THINKING SCENARIO Initiating antihypertensive therapy

THE SITUATION B.R., a 46-year-old Indigenous Australian male business executive, was seen for a routine insurance physical. His examination was normal except for a blood pressure reading of 164/102 mmHg. He also was approximately 10 kg overweight. Urinalysis and blood work results were all within normal limits. He was given a 5000-kilojoule-per-day diet to follow and was encouraged to reduce his salt and alcohol intake, start exercising and stop smoking. He was asked to return in 3 weeks for a follow-up appointment. Three weeks later, B.R. returned with a 3.5 kg weight loss and an average blood pressure reading (of three readings) of 145/92 mmHg. Discussion was held about starting B.R. on a diuretic in addition to the lifestyle changes that B.R. was undertaking. B.R. was reluctant to take a diuretic and, after much discussion, was prescribed a calcium channel blocker. B.R. asked for a couple more weeks to try to bring his blood pressure down with lifestyle changes before starting the drug. CRITICAL THINKING What care interventions should be done at this point? Consider the risk factors that B.R. has for hypertension and the damage that hypertension can cause. What are the chances that B.R. can bring his blood pressure within a normal range with lifestyle changes alone?

What additional teaching points should be covered with B.R. before a treatment decision is made? What implication does the diagnosis of hypertension have for B.R.’s insurance and job security? What effects could diuretic therapy have on B.R.’s busy business day? DISCUSSION B.R. was asked to change many things in his life over the last 3 weeks. These changes themselves can be stressful and can increase a person’s blood pressure. B.R.’s reluctance to take a diuretic is understandable for a business executive who might not want his day interrupted by many bathroom stops. B.R. should receive a complete teaching program outlining what is known about hypertension and all of the risk factors involved with the disease. The good effects of weight loss, exercise and other lifestyle changes should be stressed, and B.R. should be praised for his success over the last 3 weeks. B.R. may benefit from trying for a couple more weeks to make lifestyle changes that will help bring his blood pressure into normal range. He will then feel that he has some control and input into the situation, and if drug therapy is needed, he may be more willing to comply with the prescribed treatment. The diagnosis of hypertension may be delayed for these 2 weeks while B.R. changes his lifestyle. Such a diagnosis should be made only after three