Mst (Morphine Sulfate Pentahydrate)

• Mst is an opioid analgesic indicated for pain conditions that involve the central nervous system's nociceptive pathways.
• Acute pain: provides rapid analgesia for moderate to severe pain episodes in adults.
• Post‑operative pain: helps control surgical pain during the recovery period.
• Cancer‑related pain: offers sustained relief for persistent pain associated with malignant disease.

• Morphine sulfate pentahydrate acts as a full agonist at mu‑opioid receptors in the central nervous system. Binding to these G‑protein‑coupled receptors inhibits adenylate cyclase, reduces calcium influx, and increases potassium efflux, which collectively dampens neuronal excitability and blocks transmission of pain signals along the ascending nociceptive pathways.

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Constipation: reduced bowel motility.
• Drowsiness: increased sleepiness.
• Dizziness: sensation of light‑headedness.
• Dry mouth: reduced salivation.
• Sweating: excessive perspiration.

Serious or Rare Side Effects

• Respiratory depression: slowed or shallow breathing.
• Severe hypotension: marked drop in blood pressure.
• Anaphylactic reaction: life‑threatening allergy.
• Adrenal insufficiency: impaired cortisol response.
• Seizures: uncontrolled convulsions.
• Dependence or addiction: potential for misuse.

• Before prescribing Mst, clinicians should consider patient‑specific factors and monitor for adverse outcomes.
• Assess pain severity: confirm that opioid therapy is appropriate for the level of pain.
• Monitor respiratory function: watch for signs of respiratory depression, especially after dose initiation.
• Evaluate renal and hepatic function: adjust dosing in patients with organ impairment.
• Avoid concurrent CNS depressants: limit use with benzodiazepines, barbiturates, or alcohol.
• Use caution in the elderly: start with the lowest effective dose and titrate slowly.
• Store at ambient temperature: keep in the original pack, protect from moisture and direct sunlight.

Mst may interact with other medicines, requiring careful management.

Major Interactions (Avoid)

• Other opioids: additive respiratory depression.
• CNS depressants (e.g., benzodiazepines): heightened sedation.
• MAO inhibitors: risk of severe hypotension.
• Alcohol: increased central nervous system depression.
• Respiratory depressants (e.g., anesthetic gases): profound breathing suppression.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., erythromycin): may raise morphine levels.
• CYP3A4 inducers (e.g., rifampin): may lower efficacy.
• Diuretics: potential for electrolyte imbalance.
• Antihistamines: enhanced drowsiness.
• Anticholinergics: may worsen constipation.