ORAMORPH SR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ORAMORPH SR (ORAMORPH SR).
Morphine is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can interact with other opioid receptors at higher doses. Binding to mu-opioid receptors in the central nervous system (CNS) and peripheral tissues results in analgesia, euphoria, sedation, respiratory depression, and physical dependence. Morphine also activates descending inhibitory pathways and inhibits ascending nociceptive transmission.
| Metabolism | Primarily metabolized via glucuronidation in the liver to morphine-3-glucuronide (M3G, major inactive metabolite) and morphine-6-glucuronide (M6G, active metabolite with analgesic and respiratory depressant effects). Minor metabolism via sulfation. Involved enzymes: UGT2B7 (primary), UGT1A1, UGT1A3, UGT1A8. CYP450 enzymes play a minimal role. |
| Excretion | Renal (approximately 90% as morphine-3-glucuronide and morphine-6-glucuronide, minor amounts of unchanged morphine, and other conjugates); biliary/fecal (approximately 10%). |
| Half-life | 2–4 hours in adults; in controlled-release formulation, effective half-life is prolonged due to sustained absorption. Clinically, steady-state is achieved in 1–2 days. |
| Protein binding | 30–35% bound, primarily to albumin. |
| Volume of Distribution | 3–5 L/kg (large Vd indicates extensive tissue distribution, including sequestration in skeletal muscle and fat). |
| Bioavailability | Oral (immediate-release): 20–40% (first-pass metabolism); Oral (controlled-release): approximately 15–30% (slightly lower due to slow release formulation). |
| Onset of Action | Oral (immediate-release): 30–60 minutes; Oral (controlled-release, ORAMORPH SR): 1–2 hours |
| Duration of Action | Oral (controlled-release, ORAMORPH SR): 8–12 hours; clinical note: analgesic effect may last up to 12 hours with steady-state dosing. |
10-30 mg orally every 8-12 hours, sustained-release; titrate as needed for pain.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 10-50 mL/min: administer 75% of usual dose every 12 hours; GFR <10 mL/min: administer 50% of usual dose every 12 hours. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50% and monitor; Class C: reduce dose by 75% or consider alternative. |
| Pediatric use | 0.2-0.4 mg/kg/dose orally every 12 hours as sustained-release; maximum 1 mg/kg/dose; not recommended for children <6 months. |
| Geriatric use | Start at the low end of dosing range (e.g., 10 mg every 12 hours) and titrate cautiously due to increased sensitivity and risk of respiratory depression; consider renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ORAMORPH SR (ORAMORPH SR).
| Breastfeeding | Morphine is excreted into breast milk with M/P ratio approximately 2.5. Monitor infant for respiratory depression and withdrawal. Doses up to 30 mg/day orally are considered compatible with breastfeeding, but higher doses or chronic use require caution. |
| Teratogenic Risk | First trimester: Limited human data, but animal studies show no teratogenicity at clinically relevant doses. Second and third trimesters: Chronic use may lead to fetal dependence and neonatal withdrawal syndrome (neonatal abstinence syndrome); use only if clearly needed. Risk of preterm labor and low birth weight with prolonged use. |
■ FDA Black Box Warning
["Addiction, Abuse, and Misuse: ORAMORPH SR exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient's risk before prescribing.","Life-Threatening Respiratory Depression: Serious, life-threatening, or fatal respiratory depression may occur. Monitor for respiratory depression, especially during initiation or following a dose increase.","Accidental Ingestion: Accidental ingestion of even one dose of ORAMORPH SR, especially by children, can result in a fatal overdose of morphine.","Neonatal Opioid Withdrawal Syndrome: Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated.","Cytochrome P450 3A4 Interaction: The concomitant use of ORAMORPH SR with all cytochrome P450 3A4 inhibitors may result in an increase in morphine plasma concentrations, which could increase or prolong adverse reactions and may cause potentially fatal respiratory depression. In addition, discontinuation of a concomitantly used cytochrome P450 3A4 inducer may result in an increase in morphine plasma concentration.","Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants: Concomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants may result in profound sedation, respiratory depression, coma, and death."]
| Serious Effects |
["Significant respiratory depression","Acute or severe bronchial asthma in an unmonitored setting or in absence of resuscitative equipment","Known or suspected gastrointestinal obstruction, including paralytic ileus","Hypersensitivity to morphine or any component of the formulation"]
Loading safety data…
| Fetal Monitoring | Monitor maternal respiratory rate, sedation level, and oxygen saturation. Fetal monitoring includes non-stress test and biophysical profile as appropriate for gestational age. Assess for signs of neonatal withdrawal after delivery (e.g., Naloxone administration, Finnegan scoring). |
| Fertility Effects | Animal studies show no significant impairment of fertility at therapeutic doses. Human data limited; chronic opioid use may suppress ovulation and spermatogenesis due to hypothalamic-pituitary-gonadal axis suppression. |
| Precautions | ["Addiction, abuse, and misuse","Life-threatening respiratory depression","Accidental ingestion","Neonatal opioid withdrawal syndrome","Interaction with benzodiazepines and other CNS depressants","Chronic pulmonary disease: increased risk of respiratory depression","Head injury and increased intracranial pressure: may exacerbate effects","Hepatic or renal impairment: increased risk of toxicity","Hypotensive effects: caution in patients with circulatory shock","Gastrointestinal effects: may cause constipation; avoid in suspected paralytic ileus","Seizures: may aggravate seizure disorders","Biliary tract disease: may cause spasm of the sphincter of Oddi","Driving and operating machinery: may impair mental/physical abilities"] |