Carisoprodol is a centrally acting muscle relaxant that has been in use for more than fifty years without significant evidence for causing hepatic injury.
Carisoprodol (kar eye" soe proe' dol) is a carbamate derivative similar to meprobamate. Its mechanism of action as a muscle relaxant is unknown, but it is a sedative and may act centrally by modifying perception of pain without affecting pain reflexes. Carisoprodol is recommended for treatment of acute, painful disorders of the musculoskeletal system. Carisoprodol is available in 250 and 350 mg tablets in generic formulations and under the trade names of Soma, Carisoma, Sodol and Vanadom. Fixed combinations of carisoprodol with aspirin or codeine are also available. The recommended adult dosage is 250 to 350 mg three to four times daily for 2 to 3 weeks. Carisoprodol was approved for use in the United States in 1959 and is widely used with more than 10 million prescriptions filled yearly. It is available by prescription only and is classified as a Schedule IV agent, meaning that it has low potential for abuse and physical or psychological dependence and has an accepted medical usefulness. Common side effects include dizziness, drowsiness and headache. Overdose can cause progressive obtundation, coma, neuromuscular rigidity, myoclonus and seizures.
There have been no adequate prospective studies demonstrating the rates of aminotransferase elevations on carisoprodol therapy or convincing case reports of clinically apparent liver injury due to carisoprodol. Thus, the hepatotoxic potential of this medication is low. It has been increasingly reported as a substance of abuse, taken in higher than recommended doses.
Likelihood score: E (Unlikely cause of clinically apparent liver injury).
REPRESENTATIVE TRADE NAMES
Carisoprodol – Generic, Soma®
Autonomic Agents: Muscle Relaxants, Central
Product labeling at DailyMed, National Library of Medicine, NIH
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References updated: 30 January 2017
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Citation (Among ~50,000 liver transplants done in the US between 1990 and 2002, 270 [0.5%] were done for drug induced acute liver failure, but none were attributed to a specific muscle relaxant).
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Hernández N, Bessone F, Sánchez A, di Pace M, Brahm J, Zapata R, A Chirino R, et al. Profile of idiosyncratic drug induced liver injury in Latin America: an analysis of published reports. Ann Hepatol 2014; 13: 231-9. PubMed Citation (Among 176 reports of drug induced liver injury from Latin America published between 1996 and 2012, none were attributed to carisoprodol or other muscle relaxants).
Chalasani N, Bonkovsky HL, Fontana R, Lee W, Stolz A, Talwalkar J, Reddy KR, et al.; United States Drug Induced Liver Injury Network. Features and outcomes of 899 patients with drug-induced liver injury: The DILIN Prospective Study. Gastroenterology 2015; 148: 1340-1352. PubMed Citation (Among 899 cases of drug induced liver injury enrolled in a US prospective study between 2004 and 2013, 5 [0.7%] were attributed to muscle relaxants [2 to dantrolene, and 1 each to baclofen, metaxalone and tizanidine], but none were attributed to carisoprodol).