CNS

Analgesics (Opioid & Non-Opioid)

CNS Medications

Mark this drug class

Examples

morphinefentanylcodeine (opioid)ibuprofenacetaminophen (non-opioid)

Prefix / Suffix: Opioids often end in -ine or -one

Physiology

Pain signals travel via nociceptors to the spinal cord and brain. Opioids act centrally on opioid receptors; non-opioids act peripherally on prostaglandin synthesis or centrally without opioid effects.

Mechanism of Action

Opioids bind mu, kappa, and delta receptors in the CNS to block pain perception. NSAIDs inhibit COX enzymes, reducing prostaglandins. Acetaminophen acts centrally to reduce pain and fever.

Indications

  • Mild to severe pain
  • Post-operative pain
  • Cancer pain (opioids)
  • Fever (acetaminophen, NSAIDs)
  • Inflammation (NSAIDs)

Side Effects / Adverse Effects

  • Opioids: respiratory depression, constipation, sedation, urinary retention, dependence
  • NSAIDs: GI bleeding, renal impairment, increased cardiovascular risk
  • Acetaminophen: hepatotoxicity (especially in overdose)

Contraindications

  • Opioids: respiratory depression, paralytic ileus
  • NSAIDs: active GI bleed, severe renal impairment, late pregnancy
  • Acetaminophen: severe liver disease

Nursing Considerations

  • Assess pain using a standardized scale before and after administration
  • Monitor respiratory rate before giving opioids — hold if RR <12 (respiratory depression)
  • Have naloxone available as opioid reversal agent
  • Prevent constipation with opioids — increase fluids, fiber, stool softeners
  • Monitor liver function with acetaminophen; max 4 g/day in adults (3 g if liver disease)
  • Give NSAIDs with food to reduce GI upset
  • Educate about non-pharmacological pain relief (positioning, ice/heat, distraction)

Ask PharmPal Nurse

Your AI tutor for Analgesics (Opioid & Non-Opioid)

Ask me anything about this drug class.

Disclaimer: PharmPal Nurse is for education only and is not medical advice. Do not use it to diagnose, treat, prescribe, or make patient-care decisions; always verify with current drug references, your instructor, facility policy, and a licensed provider. In emergencies, call local emergency services.