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Clinical Studies Experience

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect rates observed in practice.

The data described below are based on 1387 patients pooled from two double blind, randomized, multicenter, placebo controlled, one-week trials in adult patients with acute, mechanical, lower back pain [see Clinical Studies]. In these studies, patients were treated with 250 mg of SOMA (carisoprodol) , 350 mg of SOMA (carisoprodol) , or placebo three times a day and at bedtime for seven days. The mean age was about 41 years old with 54% females and 46% males and 74 % Caucasian, 16 % Black, 9% Asian, and 2% other.

There were no deaths and there were no serious adverse reactions in these two trials. In these two studies, 2.7%, 2%, and 5.4%, of patients treated with placebo, 250 mg of SOMA (carisoprodol) , and 350 mg of SOMA (carisoprodol) , respectively, discontinued due to adverse events; and 0.5%, 0.5%, and 1.8% of patients treated with placebo, 250 mg of SOMA (carisoprodol) , and 350 mg of SOMA (carisoprodol) , respectively, discontinued due to central nervous system adverse reactions.

Table 1 displays adverse reactions reported with frequencies greater than 2% and more frequently than placebo in patients treated with SOMA (carisoprodol) in the two trials described above.

Table 1. Patients with Adverse Reactions in Controlled Studies

Postmarketing Experience

The following events have been reported during postapproval use of SOMA (carisoprodol) . Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Cardiovascular

Tachycardia, postural hypotension, and facial flushing [see OVERDOSAGE].

Central Nervous System

Drowsiness, dizziness, vertigo, ataxia, tremor, agitation, irritability, headache, depressive reactions, syncope, insomnia, and seizures [see OVERDOSAGE].

Gastrointestinal

Nausea, vomiting, and epigastric discomfort.

Hematologic

Leukopenia, pancytopenia

CNS Depressants

The sedative effects of SOMA (carisoprodol) and other CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may be additive. Therefore, caution should be exercised with patients who take more than one of these CNS depressants simultaneously. Concomitant use of SOMA (carisoprodol) and meprobamate, a metabolite of SOMA (carisoprodol) , is not recommended [see WARNINGS AND PRECAUTIONS].

CYP2C19 Inhibitors and Inducers

Carisoprodol is metabolized in the liver by CYP2C19 to form meprobamate [see CLINICAL PHARMACOLOGY]. Co-administration of CYP2C19 inhibitors, such as omeprazole or fluvoxamine, with SOMA could result in increased exposure of carisoprodol and decreased exposure of meprobamate. Co-administration of CYP2C19 inducers, such as rifampin or St. John's Wort, with SOMA could result in decreased exposure of carisoprodol and increased exposure of meprobamate. Low dose aspirin also showed an induction effect on CYP2C19. The full pharmacological impact of these potential alterations of exposures in terms of either efficacy or safety of SOMA (carisoprodol) is unknown.

Drug Abuse And Dependence

SOMA (carisoprodol) is not a controlled substance [see WARNINGS AND PRECAUTIONS]. Discontinuation of carisoprodol in animals or in humans after chronic administration can produce withdrawal signs, and there are published case reports of human carisoprodol dependence.

In vitro studies demonstrate that carisoprodol elicits barbiturate-like effects. Animal behavioral studies indicate that carisoprodol produces rewarding effects. Monkeys self administer carisoprodol. Drug discrimination studies using rats indicate that carisoprodol has positive reinforcing and discriminative effects similar to barbital, meprobamate, and chlordiazepoxide.

Last reviewed on RxList: 12/28/2010
This monograph has been modified to include the generic and brand name in many instances.