McKenna's Pharmacology for Nursing, 2e

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P A R T 4  Drugs acting on the central and peripheral nervous systems

If TCAs are combined with sympathomimetics or clonidine, the risk of arrhythmias and hypertension is increased. This combination should be avoided, espe­ cially in people with underlying cardiovascular disease. The combination of TCAs with MAO inhibitors leads to a risk of severe hyperpyretic crisis with severe convulsions, hypertensive episodes and death. This com­ bination should be avoided. Although TCAs and MAO inhibitors have been used together in selected individuals who do not respond to a single agent, the risk of severe adverse effects is very high.

■■ Affect is a term that refers to the feelings that people experience when they respond emotionally. ■■ Depression is an affective disorder characterised by inappropriate sadness, despair and hopelessness. ■■ According to the biogenic amine theory, depression is caused by a brain deficiency of the biogenic amines. Antidepressant drugs are thought to raise the level of the biogenic amines. ■■ Antidepressant discontinuation syndrome may occur within 5 days of stopping treatment with antidepressant drugs; symptoms are usually mild and self-limiting (lasting for 1–2 weeks), but in some cases may be severe. to decrease the risk of injury. Elderly people may not be able to tolerate larger doses. ■ ■ Reduce dose if minor adverse effects occur, and discontinue the drug slowly if major or potentially life threatening adverse effects occur to ensure safety. ■ ■ Provide comfort measures to help the person tolerate drug effects. These measures may include voiding before dosing, instituting a bowel program as needed, taking food with the drug if GI upset is severe and environmental control (lighting, temperature, stimuli). ■ ■ Provide thorough teaching, including drug name, prescribed dosage, measures for avoidance of adverse effects and warning signs that may indicate possible problems. Instruct the person about the need for periodic monitoring and evaluation to enhance knowledge about drug therapy and to promote compliance. ■ ■ Offer support and encouragement to help the person cope with the diagnosis and the drug regimen. Evaluation ■ ■ Monitor response to the drug (alleviation of signs and symptoms of depression). ■ ■ Monitor for adverse effects (sedation, anticholinergic effects, hypotension, cardiac arrhythmias, suicidal thoughts). ■ ■ Evaluate the effectiveness of the teaching plan (person can give the drug name, dosage, possible adverse effects to watch for, specific measures to help avoid adverse effects and importance of continued follow-up). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen.

Care considerations for people receiving tricyclic antidepressants

Assessment: History and examination

■ ■ Assess for any known allergies to these drugs to avoid hypersensitivity reactions ; impaired liver or kidney function, which could alter metabolism and excretion of the drug ; glaucoma, benign prostatic hypertrophy, cardiac dysfunction, GI obstruction, surgery or recent myocardial infarction, all of which could be exacerbated by the effects of the drug ; and pregnancy or breastfeeding to avoid potential adverse effects on the fetus or baby . ■ ■ Assess whether the person has a history of seizure disorders or a history of psychiatric problems or suicidal thoughts, or myelography within the past 24 hours or in the next 48 hours, or is taking an MAO inhibitor, to avoid potentially serious adverse reactions. ■ ■ Assess temperature and weight; skin colour and lesions; affect, orientation and reflexes; vision; blood pressure, including orthostatic blood pressure; pulse and perfusion; respiratory rate and adventitious sounds; and bowel sounds on abdominal examination. This determines baseline status before beginning therapy and for any potential adverse effects. Also obtain an electrocardiogram, as well as renal and liver function tests. Implementation with rationale ■ ■ Limit drug access if the person is suicidal to decrease the risk of overdose. ■ ■ Maintain the initial dose for 4 to 8 weeks to evaluate the therapeutic effect. ■ ■ Administer parenteral forms of the drug only if oral forms are not feasible or available; switch to an oral form, which is less toxic and associated with fewer adverse effects , as soon as possible. ■ ■ Administer a major portion of the dose at bedtime if drowsiness and anticholinergic effects are severe

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