McKenna's Pharmacology for Nursing, 2e

C H A P T E R 2 6 Opioids, opioid antagonists and antimigraine agents 407

constipation and biliary spasm may occur as a result of CTZ stimulation and the negative effects on GI motility. Light-headedness, dizziness, psychoses, anxiety, fear, hallucinations and impaired mental processes may occur as a result of the activation of CNS opioid receptors in the cerebrum, limbic system and hypothalamus. GU effects, including ureteral spasm, urinary retention, hesitancy and loss of libido, may be related to direct receptor stim- ulation or to CNS activation of sympathetic pathways. Although sweating and dependence, both physical and psychological, are possible, their occurrence is consid- ered less likely than with opioid agonists. Clinically important drug–drug interactions When opioid agonists–antagonists, like opioid agonists, are given with barbiturate general anaesthetics, the likelihood of respiratory depression, hypotension, and sedation or coma increases. If this combination cannot be avoided, individuals should be monitored closely and appropriate supportive measures taken. Use of opioid agonists–antagonists in people who have previously received any opioid puts these indi- viduals at risk for increased adverse effects, including respiratory depression. When such a sequence of drugs is used, individuals will require support and monitoring. ■ ■ Assess for contraindications or cautions: any known allergies to these drugs to avoid hypersensitivity reactions ; respiratory dysfunction, which may be exacerbated by the respiratory depression caused by these drugs ; MI or CAD, which could be exacerbated by the effects of these drugs ; renal or hepatic dysfunction, which might interfere with drug metabolism or excretion ; current status of pregnancy and breastfeeding, which require cautious use of the drugs ; diarrhoea caused by toxic poisons because depression of GI activity could lead to increased absorption and toxicity ; and after biliary surgery or surgical anastomoses because of the adverse effects associated with slowed GI activity due to opioids. ■ ■ Perform a pain assessment with the person to establish baseline status and evaluate the effectiveness of drug therapy. ■ ■ Perform a physical assessment to establish baseline status before beginning therapy, determine drug effectiveness and evaluate for any potential adverse effects. Care considerations for people receiving opioid agonists and opioid agonists–antagonists Assessment: History and examination

■ ■ Assess orientation, affect, reflexes and pupil size to evaluate any CNS effects ; monitor respiratory rate and auscultate lungs for adventitious sounds to evaluate respiratory effects. ■ ■ Monitor pulse, blood pressure and cardiac output to evaluate for cardiac effects. ■ ■ Palpate abdomen for distension and auscultate bowel sounds to monitor for GI effects ; assess urine output and palpate for bladder distension to evaluate for GU effects. ■ ■ Monitor the results of laboratory tests such as liver and renal function tests to determine the need for possible dose adjustment and identify toxic drug effects . Implementation with rationale ■ ■ Perform baseline and periodic pain assessments to monitor drug effectiveness and provide appropriate changes in pain management protocol as needed . ■ ■ Have an opioid antagonist and equipment for assisted ventilation readily available when administering the drug IV to provide support in case of severe reaction. ■ ■ Monitor injection sites for irritation and extravasation to provide appropriate supportive care if needed . ■ ■ Monitor timing of analgesic doses. Prompt administration may provide a more acceptable level of analgesia and lead to quicker resolution of the pain. ■ ■ Use extreme caution when injecting these drugs into any body area that has poor perfusion or shock because absorption may be delayed, and after repeated doses an excessive amount is absorbed all at once. ■ ■ Use additional measures to relieve pain (e.g. back rubs, stress reduction, hot packs, ice packs) to increase the effectiveness of the opioid being given and reduce pain. ■ ■ Monitor respiratory status before beginning therapy and periodically during therapy to monitor for potential respiratory depression. ■ ■ Institute comfort and safety measures, such as side rails and assistance with ambulation, to ensure safety ; bowel program as needed to treat constipation ; environmental controls to decrease stimulation ; and small, frequent meals to relieve GI distress if GI upset is severe. ■ ■ Reassure individuals that the risk of addiction is minimal. Most people who receive these drugs for medical reasons do not develop dependency syndromes. ■ ■ Offer support and encouragement to help the person cope with the drug regimen.