Pain Medications: Opioids, Nonopioids and PRN Decisions

Opioid Analgesics: Actions, Safety Precautions, and Adverse Effects

Opioid analgesics act by binding to mu-opioid receptors in the central nervous system. Providers may prescribe these medications to relieve moderate to severe acute pain or selected cases of persistent chronic pain. Common opioid analgesics encountered in clinical practice include morphine, hydromorphone, oxycodone, hydrocodone, and fentanyl. A critical safety distinction exists between different opioid strengths; for example, hydromorphone is significantly more potent than morphine. Because of this potency difference, the practical nurse must carefully verify the prescribed dose strength prior to administering the drug.

Transdermal fentanyl has strict safety boundaries and is reserved exclusively for opioid-tolerant clients who have severe, persistent pain that requires continuous opioid treatment. It is never used for acute pain or as a PRN medication. Furthermore, external heat applied over a fentanyl patch increases drug absorption into the bloodstream, which can cause a fatal overdose. Opioids can cause orthostatic hypotension, but the degree and mechanism of vasodilation vary by medication and client. The practical nurse reinforces teaching that clients taking opioids should change positions slowly and request assistance before ambulating if they feel dizzy or unsteady.

Respiratory depression is the most critical and life-threatening adverse effect of opioid therapy. Sedation typically precedes significant opioid-induced respiratory depression, serving as an early indicator of impending danger. Before giving any opioid analgesic, the practical nurse collects baseline data on respiratory rate, depth, and oxygen saturation, and monitors sedation levels using a validated sedation scale, such as the Pasero Opioid-Induced Sedation Scale. If the client's respiratory rate is fewer than 12 breaths per minute, the practical nurse withholds the opioid and immediately notifies the registered nurse.

If life-threatening opioid-induced respiratory depression occurs, naloxone is the opioid antagonist used for reversal. Naloxone has a shorter duration of action than most opioids; therefore, continuous monitoring is required because respiratory depression can recur once naloxone wears off. Practical nurses must also recognize that administering naloxone can cause a rapid onset of severe pain, hypertension, tachycardia, and acute withdrawal symptoms in opioid-dependent clients. Beyond respiratory depression, opioids frequently cause nausea, vomiting, pruritus, and urinary retention. If urinary retention is suspected, the practical nurse checks for bladder distention, monitors urinary output, and reports the findings to the registered nurse. Additionally, clients develop little or no tolerance to opioid-induced constipation over time. To address this, a preventive bowel regimen, commonly including a stimulant laxative with or without another bowel medication, is often prescribed when ongoing opioid therapy begins, and the practical nurse reinforces the RN's teaching on fluids, dietary fiber, and physical activity when appropriate for the client.