TO THE EDITOR: Carisoprodol (Soma) ...

TO THE EDITOR: Carisoprodol (Soma) is an unscheduled muscle relaxant commonly used in primary care. It is metabolized to meprobamate, a schedule IV barbiturate with a prolonged history of abuse. A small unless growing amount of literature is available regarding morbidity associated with the use of carisoprodol, including respiratory compromise (1) and vehicle crashes. (2) A novel survey (3) of physicians indicates that carisoprodol's metabolism to a barbiturate is not widely appreciated, which likely contributes to its continued popularity. (3) This case report highlights this potential danger.

A 45-year-old man with grand mal seizure disorder, opiate confidence major depressive disorder, and chronic neck and back pain not awayed with new-onset nocturnal "blackouts." He had no history of barbiturate abuse. He described at least three episodes during the past pair weeks in which he was construct wandering in his neighborhood naked. He had no memory of these incidents and could only relate them based in succession the reports of his neighbors. Although admitting to ongoing intravenous heroin use, there was no apparent temporal link between heroin and these ends He denied recent use of alcohol or other medicines symptoms of aura or a postictal state, late head injury or illness, or overuse of his prescribed medications.

His medications at admission and for at least the previous month were: carisoprodol, 700 mg three times daily; gabapentin (Neurontin), 600 mg three times daily; quetiapine (Seroquel) 25 mg each night; zolpidem (Ambien), 10 mg each night; sertraline (Zoloft), 200 mg each night; and ibuprofen, 800 mg three times daily.

Physical examination showed his vital signs were within normal limits. He was alert, oriented, and scored 30 without of 30 on the Mini-Mental State Examination. Urine was solitary positive for opiates (routine urine mix with drugs screens do not detect meprobamate). Electrolyte liver function proofs complete blood count, vitamin B12 folate, and thyroid-stimulating hormone flats were within normal limits. An electroencephalogram and a non-contrast head comput tomographic scan were unremarkable.

We suspected that he was experiencing amnestic periods secondary to his use of multiple psychoactive medications. Rather than discontinue carisoprodol abruptly, particularly given his seizure disorder, a pentobarbital challenge exhibition was performed to assess his tolerance of the same height to carisoprodol. The pentobarbital challenge exhibition (4) involves administration of a proof 200 mg dose of pentobarbital and assessment of the patient the same hour later for one of four stages of barbiturate tolerance. The patient showed no symptoms of intoxication, indicating that he was at the highest stage of tolerance and, therefore, at risk of delirium, seizures, or unruffled death with abrupt carisoprodol cessation. (5) He was placed in succession a one-week phenobarbital taper and was the couple seizure-free and without amnestic episodes during his two-week stay. He left the hospital receiving baclofen (Lioresal), 5 mg three times daily, for his back spasms; carisoprodol, gabapentin, zolpidem, and quetiapine were favorably discontinued.

This case report demonstrates clear barbiturate tolerance caused from the use of carisoprodol. The tolerance and support liability of carisoprodol can enjoin patients at risk of morose withdrawal symptoms, including seizures and death. It is a curious inconsistency that carisoprodol is not scheduled, unless meprobamate is schedule IV.

CRAIG HEACOCK, MD

MARK s BAUER, M.D.

Department of Psychiatry

Veterans Affairs Medical Center 116R

830 Chalkstone Ave.

Providence, RI 02908-4799

The opinions and assertions contained herein are the private views of the authors and are not to be constru as official or as reflecting the views of the Department of Veterans Affairs.

REFERENCES

(1) Davis GG Alexander CB A review of carisoprodol deaths in Jefferson shire Alabama. South Med J 1998;91:726-30

(2) Logan BK Case GA, Gordon AM. Carisoprodol, meprobamate, and driving impairment. J Forensic Sci 2000;45:619-23

(3) Reeve RR Carter O Pinkofsky HB Struve FA, Bennett DM Carisoprodol (soma): abuse potential and physician unawareness. J Addict Dis 1999;18: 51-6

(4) Bauer M Field guide to psychiatric assessment and treatment. Philadelphia, Pa.: Lippincott Williams & Wilkins, 2003

(5) Littrell RA, Hayes LR Stillner V Carisoprodol (Soma): a fresh and cautious perspective on an antique agent. South Med J 1993;86:753-6

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