McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 2 1 Antidepressant agents

Care considerations for people receiving monoamine oxidase inhibitors

■■ The MAO inhibitors prevent the breakdown of noradrenaline and 5HT by monoamine oxidase, leading to an increased level of these biogenic amines in the synaptic cleft. This accumulation of the amines is thought to relieve the signs and symptoms of depression. ■■ People taking MAO inhibitors need to avoid foods high in tyramine to prevent serious increases in blood pressure and hypertensive crises. sympathomimetic effects, hypotension, cardiac arrhythmias, GI disturbances, hypertensive crisis). ■ ■ 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, importance of continued follow-up and importance of avoiding foods high in tyramine). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. Selective serotonin reuptake inhibitors (SSRIs) (Table 21.4), the newest large group of antidepressant drugs, specifically block the reuptake of 5HT, with little to no known effect on noradrenaline. Because SSRIs do not have the many adverse effects associated with TCAs and MAO inhibitors, they are a better choice for many people. SSRIs include fluoxetine ( Prozac ), the first SSRI; citalopram ( Cipramil ); duloxetine (not available in New Zealand) ( Cymbalta ), the newest SSRI; escitalopram ( Lexapro ), fluvoxamine (not available in New Zealand) KEY POINTS ■ ■ Provide a list of potential drug–food interactions that can cause severe toxicity to decrease the risk of a serious drug–food interaction. Provide a diet that is low in tyramine-containing foods. ■ ■ 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 disease and the drug regimen. Evaluation ■ ■ Monitor response to the drug (alleviation of signs and symptoms of depression). ■ ■ Monitor for adverse effects (sedation, SELECTIVE SEROTONIN REUPTAKE INHIBITORS

Assessment: History and examination

■ ■ Assess for any known allergies to these drugs to avoid hypersensitivity reactions ; impaired liver or kidney function that could alter the metabolism and excretion of the drug ; cardiac dysfunction; GI or GU obstruction, which could be exacerbated by the drug ; surgery, including elective surgery, because the effects of changes in noradrenaline levels are unpredictable following surgery ; seizure disorders; psychiatric conditions or suicidality; and occurrence of myelography within the past 24 hours or in the next 48 hours to avoid the possibility of severe reactions . ■ ■ Determine whether women are pregnant or breastfeeding because these drugs should not be used during pregnancy or breastfeeding. ■ ■ 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 to determine baseline status and for any potential adverse effects before beginning therapy. Also obtain an electrocardiogram and renal and liver function tests. Implementation with rationale ■ ■ Limit drug access to a potentially suicidal person to decrease the risk of overdose. ■ ■ Monitor the person for 2 to 4 weeks to ascertain the onset of the full therapeutic effect. ■ ■ Monitor blood pressure and orthostatic blood pressure carefully to arrange for a slower increase in dose as needed for people who show a tendency towards hypotension. ■ ■ Monitor liver function before and periodically during therapy and arrange to discontinue the drug at the first sign of liver toxicity. ■ ■ Discontinue drug and monitor the person carefully at any complaint of severe headache to decrease the risk of severe hypertension and cerebrovascular effects. ■ ■ Have phentolamine or another adrenergic blocker on standby as treatment in case of hypertensive crisis. ■ ■ Provide comfort measures to help the person tolerate drug effects. These 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, decreased stimulation).