MAOLATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MAOLATE (MAOLATE).
MAOLATE is a centrally acting muscle relaxant that does not directly relax skeletal muscle. Its mechanism of action is not fully understood, but it is thought to act via inhibition of polysynaptic reflexes at the spinal level and possibly through sedation.
| Metabolism | Hepatic metabolism via glucuronidation and oxidative pathways; CYP450 involvement not well characterized. |
| Excretion | Renal: ~70% as unchanged drug and metabolites; Biliary/Fecal: ~30% |
| Half-life | Terminal elimination half-life: 8-12 hours (prolonged in renal impairment, up to 20-30 hours in severe renal failure; dose adjustment required for CrCl <30 mL/min) |
| Protein binding | 98% bound to albumin |
| Volume of Distribution | 0.15-0.25 L/kg, indicating limited extravascular distribution |
| Bioavailability | Oral: 75-85% (first-pass metabolism reduces absorption) |
| Onset of Action | Oral: 30-60 minutes; IV: 5-10 minutes |
| Duration of Action | 4-6 hours (may be longer in hepatic impairment due to reduced clearance) |
250 mg orally 4 times daily or 500 mg orally 3 times daily for 21 days; maximum daily dose 2000 mg.
| Dosage form | TABLET |
| Renal impairment | GFR >= 50 mL/min: no adjustment; GFR 30-49 mL/min: 250 mg twice daily; GFR 10-29 mL/min: 250 mg once daily; GFR < 10 mL/min: 250 mg every 48 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: 250 mg once daily; Child-Pugh C: contraindicated. |
| Pediatric use | Not established; safety and efficacy not determined in patients < 18 years. |
| Geriatric use | Start at lower end of dosing (250 mg twice daily) due to age-related renal impairment; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MAOLATE (MAOLATE).
| Breastfeeding | Methocarbamol is excreted in human milk in small amounts. M/P ratio unknown. Caution advised; monitor infant for sedation, poor feeding, or hypotonia. |
| Teratogenic Risk | MAOLATE (methocarbamol): No well-controlled studies in pregnant women. Animal studies show no teratogenic effects at doses up to 3 times the human dose. First trimester: Limited data; theoretical risk based on muscle relaxant properties. Second and third trimesters: Use only if clearly needed; may cause neonatal hypotonia and respiratory depression if used near term. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to maolate or any component of the formulation.","Patients with porphyria.","Patients with acute intermittent porphyria.","Concomitant use with MAO inhibitors (potential for increased CNS depression)."]
| Precautions | ["May cause sedation and dizziness; caution with activities requiring alertness.","Use with caution in patients with hepatic or renal impairment.","Potential for abuse and dependence; use with caution in patients with history of substance abuse.","May impair ability to drive or operate machinery."] |
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| Fetal Monitoring |
| Monitor maternal blood pressure, heart rate, and respiratory status. Fetal monitoring: consider non-stress test or biophysical profile if used near term due to potential for neonatal respiratory depression. |
| Fertility Effects | No known adverse effects on fertility in animal studies. Human data lacking; theoretical concern for impaired spermatogenesis or ovulation due to central nervous system effects. |