SOMA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SOMA (SOMA).
Centrally acting muscle relaxant; acts at brainstem reticular formation and spinal cord levels to inhibit polysynaptic reflexes, possibly via GABAergic and monoaminergic pathways.
| Metabolism | Hepatic via CYP2C19 and CYP3A4; also undergoes dealkylation and hydroxylation. |
| Excretion | Renal: ~60-70% as metabolites (including meprobamate and glucuronide conjugates); fecal: minimal; biliary: negligible. |
| Half-life | 1-2 hours; prolonged to 3-4 hours in hepatic impairment; parent drug rapidly cleared via CYP2C19 metabolism to meprobamate (active, t1/2 6-16 hours). |
| Protein binding | ~60% bound to albumin. |
| Volume of Distribution | 0.7-1.0 L/kg; consistent with moderate tissue distribution. |
| Bioavailability | Oral: ~100% (rapidly and completely absorbed). |
| Onset of Action | Oral: 30 minutes; peak effect at 1-2 hours. |
| Duration of Action | 2-4 hours for sedative effect; muscle relaxant effects may persist up to 6 hours; repeated dosing leads to tolerance and shorter duration. |
250 mg to 350 mg orally three times daily and at bedtime.
| Dosage form | CAPSULE |
| Renal impairment | No specific dose adjustment guidelines; use with caution in severe renal impairment (GFR <30 mL/min). |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). Use with caution in mild to moderate impairment; reduce dose or extend dosing interval. |
| Pediatric use | Not recommended for children under 12 years of age. For adolescents, adult dosing may be considered based on weight and clinical judgment. |
| Geriatric use | Initiate at lower doses (e.g., 250 mg three times daily) due to increased sensitivity and risk of CNS adverse effects; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SOMA (SOMA).
| Breastfeeding | M/P ratio unknown. Carisoprodol and its active metabolite meprobamate are excreted in breast milk. Potential for sedation in nursing infants. Use caution; monitor infant for drowsiness and feeding difficulties. |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: Limited human data; animal studies show increased fetal resorptions and skeletal anomalies. Second/third trimester: Risk of neonatal withdrawal syndrome (irritability, hypertonia) with chronic maternal use near term. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to carisoprodol or its components","Acute intermittent porphyria","Concurrent use with other CNS depressants (relative)"]
| Precautions | ["May cause sedation, dizziness, and impaired psychomotor function; avoid driving or operating machinery.","Risk of abuse, dependence, and withdrawal; use with caution in patients with substance use disorder.","Concomitant use with alcohol or other CNS depressants may potentiate effects.","Elderly patients more sensitive to anticholinergic effects; monitor for confusion or falls.","Hepatic impairment: reduce dose or avoid use.","Pregnancy: limited data; use only if clearly needed."] |
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| Monitor maternal CNS depression, respiratory rate, and blood pressure. Assess fetal heart rate and uterine activity if used during labor. Neonatal observation for withdrawal symptoms if chronic maternal use. |
| Fertility Effects | No human data on fertility impairment. Animal studies have not demonstrated adverse effects on fertility. |