SOMA COMPOUND
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SOMA COMPOUND (SOMA COMPOUND).
Carisoprodol is a centrally acting muscle relaxant that acts through its metabolite meprobamate, which modulates GABA-A receptors and inhibits neuronal activity in the reticular formation and spinal cord. Aspirin is a nonsteroidal anti-inflammatory drug (NSAID) that irreversibly inhibits cyclooxygenase (COX-1 and COX-2), reducing prostaglandin synthesis and providing analgesic, anti-inflammatory, and antipyretic effects.
| Metabolism | Carisoprodol is metabolized by CYP2C19 to meprobamate (active metabolite); aspirin is hydrolyzed to salicylic acid via esterases in the liver and plasma. |
| Excretion | Carisoprodol and its active metabolite meprobamate are primarily excreted renally. Approximately 60% of a dose is eliminated as unchanged carisoprodol and meprobamate in urine, with the remainder as various hydroxylated metabolites. Less than 1% is eliminated in feces. Meprobamate undergoes hepatic metabolism, and about 10-20% is excreted unchanged in urine. |
| Half-life | Carisoprodol: approximately 2-4 hours in adults with normal renal function. Meprobamate: approximately 10-12 hours. The prolonged half-life of meprobamate contributes to accumulation with repeated dosing, especially in elderly or renally impaired patients, leading to increased risk of sedation and dependence. |
| Protein binding | Carisoprodol: approximately 60% bound to plasma proteins, primarily albumin. Meprobamate: approximately 15-25% bound to plasma proteins. |
| Volume of Distribution | Carisoprodol: Vd approximately 0.5-1.0 L/kg, indicating distribution into total body water and some tissue binding. Meprobamate: Vd about 0.7 L/kg. |
| Bioavailability | Oral: Carisoprodol is well absorbed with bioavailability >90%. The absorption rate may be slightly reduced with food, but extent is not significantly affected. |
| Onset of Action | Oral: Onset of muscle relaxant effect typically occurs within 30 minutes, with peak plasma concentrations reached at 1-2 hours post-dose. |
| Duration of Action | Oral: Clinical effects last approximately 4-6 hours for carisoprodol. However, due to the long half-life of meprobamate, sedation and residual effects may persist longer. Clinical use is limited to short-term (up to 2-3 weeks) due to risk of dependence. |
1-2 tablets (carisoprodol 200mg/aspirin 325mg) orally 4 times daily.
| Dosage form | TABLET |
| Renal impairment | CrCl <30 mL/min: avoid use due to aspirin component; CrCl 30-50 mL/min: reduce dose or extend interval; monitor for carisoprodol accumulation. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | Not recommended for children under 12 years; safety and efficacy not established. |
| Geriatric use | Initiate at lowest dose (1 tablet); avoid use in patients with CrCl <30 mL/min; monitor for CNS depression and bleeding risk. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SOMA COMPOUND (SOMA COMPOUND).
| Breastfeeding | Carisoprodol and its active metabolite meprobamate are excreted in breast milk. M/P ratio not well established. Concentrations may reach clinical significance. Potential for infant sedation, hypotonia, or withdrawal. Avoid breastfeeding while on this medication. |
| Teratogenic Risk | Carisoprodol (Soma) is FDA Pregnancy Category C. Inadequate human data; animal studies suggest risk. Not recommended in first trimester due to potential teratogenicity. Aspirin component (if present in compound) is associated with increased risk of neural tube defects and fetal hemorrhage if used in third trimester. Avoid use during pregnancy unless benefit outweighs risk. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["History of acute intermittent porphyria","Hypersensitivity to carisoprodol, meprobamate, aspirin, or any component","Severe hepatic or renal impairment","Gastrointestinal bleeding or peptic ulcer disease (active)","Children with viral infections (Reye's syndrome risk)","Third trimester of pregnancy (aspirin component)"]
| Precautions | ["Dependence and withdrawal: Carisoprodol can cause dependence, abuse, and withdrawal symptoms after prolonged use","Sedation: May impair mental or physical abilities; caution with driving or operating machinery","Bleeding risk: Aspirin component increases risk of bleeding, especially with alcohol, anticoagulants, or existing bleeding disorders","Hypersensitivity: Allergic reactions including anaphylaxis can occur"] |
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| Fetal Monitoring | Monitor maternal CNS effects (sedation, dizziness). No specific fetal monitoring recommended except standard obstetric care. If used near term, monitor newborn for signs of respiratory depression or withdrawal. |
| Fertility Effects | No specific human data on fertility effects. Animal studies have not shown significant impairment. Theoretical risk due to CNS depressant effects on hormonal regulation. |