REVEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for REVEX (REVEX).
Nalmefene is an opioid antagonist that competitively binds to mu, delta, and kappa opioid receptors, reversing or preventing opioid effects.
| Metabolism | Primarily hepatic via glucuronidation; major metabolite is nalmefene glucuronide; minor CYP450 involvement. |
| Excretion | Renal: 60% as unchanged drug and metabolites; fecal: 40% via biliary elimination. |
| Half-life | Terminal elimination half-life: 2.4-4.2 hours in adults; prolonged in renal impairment (up to 50 hours). |
| Protein binding | Approximately 80% bound to albumin. |
| Volume of Distribution | Volume of distribution: 2.5-3.8 L/kg, indicating extensive tissue distribution. |
| Bioavailability | IM: 100%; subcutaneous: 100%. |
| Onset of Action | IV: within 2 minutes; IM: 5-15 minutes; subcutaneous: 15-30 minutes. |
| Duration of Action | IV: 30-60 minutes (dose-dependent); may require repeated doses due to longer half-life of opioids. |
0.5 mg to 1 mg intravenous, intramuscular, or subcutaneous, repeated every 2 to 5 minutes as needed, up to a maximum of 2 mg total dose per episode.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment for renal impairment is recommended, but use with caution in severe renal failure due to potential accumulation. |
| Liver impairment | No specific Child-Pugh-based dose adjustments are established; use with caution in hepatic impairment due to prolonged elimination. |
| Pediatric use | Initial dose of 0.5 mg per 20 kg body weight (0.025 mg/kg) intravenous, intramuscular, or subcutaneous, repeated every 2 to 5 minutes as needed, up to a maximum total of 2 mg per episode. |
| Geriatric use | No specific dose adjustment required, but consider reduced initial doses (e.g., 0.25 mg) due to age-related decline in renal and hepatic function and increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for REVEX (REVEX).
| Breastfeeding | No data on excretion in human milk; M/P ratio unknown. Potential for adverse effects in infant (hypotension, bradycardia). Consider risk-benefit. |
| Teratogenic Risk | No human data; animal studies show no teratogenicity at high doses. Risk cannot be excluded, especially in first trimester. Use only if maternal benefit outweighs fetal risk. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and oxygen saturation; fetal heart rate monitoring via electronic fetal monitoring; observe for uterine hypertonus. |
■ FDA Black Box Warning
Risk of recurrent respiratory depression: due to the duration of action of nalmefene being shorter than that of some opioids, repeated monitoring and administration may be necessary.
| Serious Effects |
["Hypersensitivity to nalmefene or any component of the formulation"]
| Precautions | ["Risk of recurrent respiratory depression due to shorter duration of action","May precipitate acute opioid withdrawal in opioid-dependent patients","Limited efficacy against buprenorphine-induced respiratory depression","Use with caution in patients with known cardiovascular disease or those taking drugs that may prolong QT interval"] |
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| Fertility Effects | No known effect on human fertility; animal studies show no impairment. |