INFUMORPH
Clinical safety rating: caution
Comprehensive clinical and safety monograph for INFUMORPH (INFUMORPH).
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. It mimics endogenous endorphins by binding to opioid receptors in the CNS, causing inhibition of ascending pain pathways and altering pain perception.
| Metabolism | Primarily hepatic via glucuronidation by UDP-glucuronosyltransferase 2B7 (UGT2B7) to morphine-3-glucuronide (M3G, inactive) and morphine-6-glucuronide (M6G, active). Minor metabolism includes sulfation and N-demethylation to normorphine. |
| Excretion | Renal elimination of morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) accounts for approximately 90% of total clearance, with <10% excreted as unchanged morphine in urine. Biliary/fecal elimination accounts for the remaining fraction (<10%). |
| Half-life | Terminal elimination half-life: 2–4 hours in healthy adults; prolonged to 4–6 hours in the elderly or those with renal impairment, leading to accumulation of active metabolites (M6G). |
| Protein binding | 30–35% bound to albumin. |
| Volume of Distribution | Vd: 3–5 L/kg. Indicates extensive tissue distribution, higher in neonates due to reduced plasma protein binding and increased lipophilicity. |
| Bioavailability | Oral immediate-release: 20–40% (first-pass metabolism); Oral extended-release: similar, but formulation-dependent; Intrathecal: nearly 100% (direct CNS delivery); Intravenous: 100%. |
| Onset of Action | Intravenous: 5–10 minutes; Oral (immediate-release): 30–60 minutes; Oral (extended-release): 2–4 hours. Intrathecal: 15–60 minutes. |
| Duration of Action | Analgesic duration: 3–6 hours for immediate-release formulations; extended-release products provide 8–24 hours. Clinical duration may be longer in patients with hepatic/renal dysfunction due to reduced clearance. |
Morphine sulfate 10-30 mg orally every 4 hours as needed; or 2.5-15 mg IV/IM/SC every 2-6 hours; or 0.5-2 mg per hour continuous IV infusion. Extended-release formulations: 15-30 mg orally every 8-12 hours.
| Dosage form | INJECTABLE |
| Renal impairment | GFR 30-60 mL/min: reduce total daily dose by 25% and administer at increased intervals (e.g., every 6-8 hours). GFR 10-29 mL/min: reduce dose by 50% and administer every 8-12 hours. GFR <10 mL/min: reduce dose by 75% and administer every 12 hours or consider alternative opioid. |
| Liver impairment | Child-Pugh Class A: no adjustment needed. Child-Pugh Class B: reduce total daily dose by 50% and lengthen dosing interval (e.g., every 6-8 hours). Child-Pugh Class C: reduce dose by 75% and administer every 8-12 hours; monitor for excessive sedation. |
| Pediatric use | Oral: 0.2-0.5 mg/kg every 4-6 hours prn; maximum single dose 15 mg. IV/IM/SC: 0.1-0.2 mg/kg every 2-4 hours prn; maximum single dose 10 mg. Continuous IV infusion: 0.01-0.04 mg/kg/hour. Use preservative-free formulations in neonates. |
| Geriatric use | Start at 25-50% of adult dose; use immediate-release formulations initially. Oral: 2.5-10 mg every 4-6 hours. IV/IM/SC: 1-5 mg every 4-6 hours. Titrate cautiously; monitor for constipation, confusion, and respiratory depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for INFUMORPH (INFUMORPH).
| Breastfeeding | Morphine enters breast milk; M/P ratio approximately 1:1 to 2:1. Use with caution; monitor infant for sedation, respiratory depression, and withdrawal. Avoid if maternal dose >20 mg/day enterally or equivalent parenteral. |
| Teratogenic Risk | Pregnancy category C. First trimester: No well-controlled studies; potential for neural tube defects if used chronically. Second/third trimesters: Chronic use may cause fetal dependence, neonatal withdrawal syndrome, and respiratory depression at delivery. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
INFUMORPH (morphine sulfate) injection is contraindicated for epidural or intrathecal administration in patients with infection at the injection site, bleeding diathesis, or concurrent anticoagulant therapy. Use of morphine by these routes carries a risk of respiratory depression, especially during the first 24 hours. Equipment and personnel for resuscitation should be immediately available. Also, morphine is an opioid agonist and a Schedule II controlled substance with abuse potential similar to other opioids.
| Serious Effects |
["Hypersensitivity to morphine or any component","Significant respiratory depression","Acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment","Known or suspected gastrointestinal obstruction, including paralytic ileus","Concurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 days of such therapy"]
| Precautions | ["Risk of life-threatening respiratory depression; monitor closely especially during initiation and dose escalation","Accidental ingestion may be fatal","Neonatal opioid withdrawal syndrome with prolonged use during pregnancy","Risk of opioid-induced hyperalgesia","Risk of serotonin syndrome with concomitant serotonergic drugs","Adrenal insufficiency with prolonged use","Severe hypotension in patients with compromised ability to maintain blood pressure","Seizures in patients with seizure disorders","Do not abruptly discontinue in physically dependent patients; taper gradually"] |
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| Fetal Monitoring |
| Monitor maternal respiratory rate, oxygen saturation, sedation level, and pain control. Fetal: heart rate monitoring (non-stress test or biophysical profile) with chronic use; assess for growth restriction via serial ultrasound. Neonatal: observe for withdrawal (e.g., NAS score) for 48-72 hours postpartum. |
| Fertility Effects | May impair fertility in both sexes. In females: possible menstrual irregularities due to hormonal changes. In males: potential for decreased libido, erectile dysfunction, and altered sperm parameters. Effects are generally reversible upon discontinuation. |