II. Precautions

  1. Schedule IV drug in U.S. as of January 2012
  2. Risk of transient neurologic changes, serious Allergic Reactions, Substance Abuse, and fatal Overdoses
  3. Metabolized to Meprobamate, a Sedative and FDA controlled substance similar to Barbiturates
  4. Two tablets (700 mg dose) may require Endotracheal Intubation in infants

III. Mechanism

  1. Carisoprodol is a centrally acting Skeletal Muscle Relaxant
  2. Meprobamate is primary active metabolite
    1. Barbiturate-like effects at GABA-A Receptors

IV. Dosing

  1. Carisoprodol (Soma) 350 mg up to four times daily

V. Pharmacokinetics

  1. Rapid absorption
  2. Rapid onset
  3. Drug Clearance (variable)
    1. Half-Life: 100 minutes
    2. Hepatic metabolism: CYP2C19
    3. Renal Excretion

VI. Adverse Effects: Toxicity or Overdose

  1. Myoclonic encephalopathy (abnormal movements)
  2. Agitation
  3. Lethargy to coma (Meprobamate related)
  4. Seizures (rare)
  5. Cardiopulmonary depression (apnea, Acute Heart Failure)
  6. Withdrawal symptoms (e.g. Delirium) after cessation

VII. Labs: Toxicity

  1. See Unknown Ingestion
  2. Complete Blood Count (CBC)
  3. Comprehensive Metabolic Panel (Chem18)
  4. Creatinine Kinase (CK)

VIII. Diagnostics: Toxicity

IX. Management: Toxicity

  1. Supportive Care
    1. ABC Management
    2. Endotracheal Intubation as indicated
  2. Gastric Decontamination is not typically indicated
  3. Sedation for Agitation, rigidity
  4. Antidotes
    1. May consider Flumazenil (but risk of severe withdrawal if concurrent Benzodiazepine Abuse)
    2. Roberge (2000) J Emerg Med 18(1):61-4 +PMID: 10645840 [PubMed]

X. References

  1. Sun and Tomaszewski (2017) Crit Dec Emerg Med 31(12): 24
  2. Høiseth (2008) Clin Toxicol 46(4):307-9 +PMID: 18363125

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Related Studies

Cost: Medications

carisoprodol (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
CARISOPRODOL 250 MG TABLET Generic $0.78 each
CARISOPRODOL 350 MG TABLET Generic $0.05 each