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 6/7/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
CARISOPRODOL 250 MG TABLET Generic $1.84 each
CARISOPRODOL 350 MG TABLET Generic $0.07 each
soma (on 10/19/2016 at Medicaid.Gov Survey of pharmacy drug pricing)
SOMA 350 MG TABLET Generic $0.07 each

Ontology: Carisoprodol (C0007248)

Definition (NCI) A synthetic propanediol dicarbamate derivative and an adjunct in the treatment of painful muscle spasms, Carisoprodol is a centrally acting skeletal muscle relaxant that relieves stiffness, pain, and discomfort caused by muscle injuries. Its mechanism of action is not clear yet; perhaps due to its sedative actions. (NCI04)
Definition (MSH) A centrally acting skeletal muscle relaxant whose mechanism of action is not completely understood but may be related to its sedative actions. It is used as an adjunct in the symptomatic treatment of musculoskeletal conditions associated with painful muscle spasm. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1202)
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH D002328
SnomedCT 25076002, 387133006
LNC LP14985-3, MTHU002288
English Carisoprodate, Carisoprodol, Isobamate, Isomeprobamate, Isopropylmeprobamate, Carbamic acid, (1-methylethyl)-, 2-(((aminocarbonyl)oxy)methyl)-2-methylpentyl ester, carisoprodol, muscle relaxants skeletal carisoprodol, carisoprodol (medication), CARISOPRODOL, Carisoprodol [Chemical/Ingredient], isopropylmeprobamate, Carisoprodol (product), Carisoprodol (substance)
Swedish Karisoprodol
Czech karisoprodol
Finnish Karisoprodoli
Italian Isobamato, Carisoprodato, Isomeprobamato, Isopropilmeprobamato, Carisoprodolo
Polish Soma, Karizoprodol
Japanese イソバメート, イソプロピルメプロバメート, イソメプロバメート, カリソプロデート, カリソプロドール
Spanish carisoprodato, carisoprodol (producto), carisoprodol (sustancia), carisoprodol, isobamato, isopropilmeprobamato, Carisoprodato, Carisoprodol, Isobamato, Isomeprobamato, Isopropilmeprobamatos
French Carisoprodol
German Carisoprodat, Carisoprodol, Isobamat, Isomeprobamat, Isopropylmeprobamat
Portuguese Carisoprodato, Carisoprodol, Isobamato, Isomeprobamato, Isopropilmeprobamato