Mst 6 (Morphine Sulfate)

Morphine sulfate is an opioid analgesic used to manage pain that involves the central nervous system pathways.

• Postoperative pain: provides strong analgesia to facilitate recovery after surgery.
• Cancer‑related pain: reduces severe nociceptive and neuropathic pain associated with malignancy.
• Acute traumatic pain: controls intense pain following injury or trauma.
• Chronic severe pain: offers long‑term relief for patients with refractory pain conditions.
• Palliative care pain: alleviates distressing pain in end‑of‑life settings.

• Morphine sulfate acts as an agonist at μ‑opioid receptors in the brainstem and spinal cord. Binding activates G‑protein‑coupled pathways that inhibit adenylate cyclase, decrease calcium influx, and increase potassium efflux, resulting in reduced neuronal excitability and suppression of nociceptive signal transmission.

Morphine sulfate may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Constipation: reduced gastrointestinal motility leading to hard stools.
• Nausea: feeling of sickness often accompanied by vomiting.
• Drowsiness: increased sleepiness or sedation.
• Dry mouth: reduced salivation causing a parched sensation.

Serious or Rare Side Effects

• Respiratory depression: slowed or shallow breathing that can be life‑threatening.
• Hypotension: significant drop in blood pressure causing dizziness.
• Dependence and withdrawal: physical and psychological reliance with withdrawal symptoms upon cessation.
• Severe allergic reaction: rash, itching, swelling, or anaphylaxis.

When prescribing morphine sulfate, clinicians should consider several safety precautions to minimize risk.

• Assess pain severity: confirm that pain is moderate to severe before initiating therapy.
• Evaluate respiratory function: avoid use in patients with compromised breathing or obstructive sleep apnea.
• Review concomitant CNS depressants: limit combined use with benzodiazepines or alcohol.
• Monitor for signs of dependence: watch for escalating dose requirements or misuse behaviors.
• Adjust dose in renal/hepatic impairment: use lower initial doses and titrate cautiously.
• Store at ambient temperature: keep below 25°C in the original container, protect from moisture and light.

Morphine sulfate can interact with other medications, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Other opioids: additive respiratory depression and sedation.
• CNS depressants (e.g., benzodiazepines, barbiturates): heightened risk of profound sedation and respiratory compromise.
• MAO inhibitors: may precipitate severe hypertension or serotonin syndrome.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): increase morphine plasma levels.
• CYP3A4 inducers (e.g., rifampin, carbamazepine): reduce analgesic effect.
• Anticholinergics: may worsen constipation.
• Diuretics: can enhance hypotensive effects.