McKenna's Pharmacology for Nursing, 2e

C H A P T E R 2 6 Opioids, opioid antagonists and antimigraine agents 413

Care considerations for people receiving antimigraine agents

■■ Migraine headaches are severe, throbbing headaches on one side of the head that may be associated with an aura or warning syndrome. These headaches are thought to be caused by arterial dilation and hyperperfusion of the brain vessels. ■■ Treatment of migraines may involve either ergot derivatives or triptans. Ergot derivatives cause vasoconstriction and are associated with sometimes severe systemic vasoconstrictive effects, whereas triptans, a newer class of selective serotonin receptor blockers, cause CNS vasoconstriction but are not associated with as many adverse systemic effects. CHAPTER SUMMARY ■■ Pain occurs any time that tissue is injured and various chemicals are released. The pain impulses are carried to the spinal cord by small-diameter A-delta and C fibres, which form synapses with interneurons in the dorsal horn of the spinal cord. ■■ Opioid receptors found throughout various tissues in the body react with endogenous endorphins and encephalins to modulate the transmission of pain impulses. ■■ Opioids, derived from the opium plant, react with opioid receptors to relieve pain. In addition, they lead to constipation, respiratory depression, sedation and suppression of the cough reflex; they also stimulate feelings of well-being or euphoria. ■ ■ Provide thorough teaching, including drug name, prescribed dose and schedule for administration; measures to avoid adverse effects; warning signs that may indicate possible problems; signs of ergotism if taking ergot derivatives; safety measures such as avoiding driving and avoiding overdose; and importance of follow-up monitoring and evaluation to enhance the person’s knowledge about drug therapy and to promote compliance. Evaluation ■ ■ Monitor the person’s response to the drug (relief of acute migraine headaches). ■ ■ Monitor for adverse effects (CV changes, arrhythmias, hypertension, CNS changes). ■ ■ Evaluate the effectiveness of the teaching plan (person can give the drug name and dosage and describe possible adverse effects to watch for, specific measures to prevent them and warning signs to report). ■ ■ Monitor the effectiveness of comfort measures and compliance with the regimen. KEY POINTS

Assessment: History and examination

■ ■ Assess for contraindications or cautions: any known allergies to any components of the drugs to avoid hypersensitivity reactions ; history of MI, CAD or hypertension, which may be exacerbated by the drug ; hepatic or renal dysfunction, which could alter the metabolism and excretion of the drug ; pruritus or malnutrition, which could be exacerbated by ergot derivatives ; and current status of pregnancy and breastfeeding, which would be cautions to the use of these drugs . ■ ■ Perform a physical assessment to establish baseline status before beginning therapy, determine drug effectiveness and evaluate for any potential adverse effects. ■ ■ Assess neurological status, including level of orientation, affect and reflexes, to evaluate CNS effects of the drugs . ■ ■ Monitor for complaints of extremity numbness and tingling to identify effects on vascular constriction. ■ ■ Inspect the skin for localised oedema, itching or breakdown with ergot derivatives to evaluate potential dermatological effects. ■ ■ Assess vital signs, including pulse rate and blood pressure; obtain an ECG as appropriate to evaluate cardiac status for changes. ■ ■ Monitor the results of laboratory tests, including liver and renal function tests, to determine the need for dose adjustment and identify possible toxic effects. ■ ■ Administer the drug to relieve acute migraines; these drugs are not used for prevention. ■ ■ Administer at the first sign of a headache and do not wait until it is severe, to improve therapeutic effectiveness. ■ ■ Arrange for safety precautions if CNS or visual changes occur to prevent injury. ■ ■ Provide comfort and safety measures, such as environmental controls and stress reduction, for the relief of headache. Provide additional pain relief as needed. ■ ■ Monitor the blood pressure of any person with a history of CAD, and discontinue the drug if any sign of angina or prolonged hypertension occurs, to prevent severe vascular effects. ■ ■ Offer support and encouragement to help the individual cope with the disorder and associated drug regimen. Implementation with rationale