McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 4 6 Antianginal agents

is a risk of contact dermatitis and local hypersensitivity reactions. Clinically important drug–drug interactions There is a risk of hypertension and decreased anti­ anginal effects if these drugs are given with ergot derivatives. There is also a risk of decreased therapeutic effects of heparin if these drugs are given together with heparin; if this combination is used, the person should be monitored and appropriate dose adjustments made. Individuals should be warned not to combine nitrates with sildenafil, tadalafil or vardenafil, drugs used to treat erectile dysfunction, because serious hypotension and cardiovascular events could occur. Prototype summary: Glyceryl trinitrate Indications: Treatment of acute angina, prophylaxis of angina, intravenous treatment of angina unresponsive to beta-blockers or organic nitrates, perioperative hypertension, and heart failure (HF) associated with acute MI; to produce controlled hypotension during surgery. Actions: Relaxes vascular smooth muscle with a resultant decrease in venous return and decrease in arterial blood pressure, reducing the left ventricular workload and decreasing myocardial oxygen consumption. Pharmacokinetics: Route Onset Duration IV 1–2 mins 3–5 mins Sublingual tablet 1–3 mins 30–60 mins Translingual spray 2 mins 30–60 mins Transmucosal tablet 1–2 mins 3–5 mins Oral, SR tablet 20–45 mins 8–12 hours Transdermal 30–60 min 24 hours T 1/2 : 1 to 4 minutes; metabolised in the liver and excreted in urine. Adverse effects: Hypotension, headache, dizziness, tachycardia, rash, flushing, nausea, vomiting, sweating, chest pain.

be exacerbated by the hypotension and change in blood flow caused by these drugs , such as early MI, head trauma, cerebral haemorrhage, hypotension, hypovolaemia, anaemia or low– cardiac output states; and current status of pregnancy or breastfeeding because of the potential for adverse effects on the fetus or breastfeeding baby. ■ ■ Perform a physical assessment to establish baseline status before beginning therapy an d during therapy to determine effectiveness and to evaluate for any potential adverse effects. ■ ■ Inspect the skin for colour, intactness and any signs of redness, irritation or breakdown, especially if the person is using the transdermal or topical form of the drug, to prevent possible skin reaction and ensure adequate surface for application and absorption of transdermal or topical drug. Also check the person’s oral or buccal mucosa (including the area under the tongue) if sublingual or buccal forms are ordered to reduce the risk of irritation and ensure adequate surface for absorption. ■ ■ Assess the person’s complaint of pain, including onset, duration, intensity, location and measures used to relieve it. Investigate activity level prior to and after the onset of pain to aid in identifying possible contributing factors to the pain and its progression. ■ ■ Assess neurological status, including level of alertness, affect and reflexes, to evaluate for CNS effects. ■ ■ Monitor respirations and auscultate lungs to evaluate changes in cardiac output. ■ ■ Assess cardiopulmonary status closely, including pulse rate, blood pressure, heart rate and rhythm, to determine the effects of therapy and identify any adverse effects. ■ ■ Obtain an ECG as ordered to evaluate heart rate and rhythm, which could indicate changes in cardiac perfusion. ■ ■ Monitor laboratory test results, including liver and renal function tests, full blood count and haemoglobin level, to determine the need for possible dose adjustment . ■ ■ Give sublingual preparations under the tongue or in the buccal pouch, and encourage the person not to swallow, to ensure that therapeutic effectiveness is achieved (see Pharmacokinetics for discussion of safe medication administration). ■ ■ Ask the person if the tablet “fizzles” or burns, which indicates potency. Always check the expiration date on the bottle and protect the Implementation with rationale

Care considerations for people receiving nitrates

Assessment: History and examination ■ ■ Assess for contraindications or cautions: any known allergies to nitrates to avoid

hypersensitivity reactions ; impaired liver or kidney function, which could alter the metabolism and excretion of the drug ; any condition that could