Carisoprodol and meprobamate: risks outweigh benefits

Marketing authorisations for carisoprodol are to be suspended after a European review concluded that the risks of treatment outweigh the benefits.

Article date: February 2008

Post-publication note: information in this article relating to meprobamate has been updated. See the article published in April 2016 for the latest advice.

Carisoprodol

Carisoprodol (Carisoma) is a centrally acting muscle relaxant used in the short term as an adjunct to the symptomatic treatment of acute musculoskeletal disorders associated with painful muscle spasm. Carisoprodol is associated with increased risk of abuse, addiction, intoxication, and psychomotor impairment. There are safer alternatives to carisoprodol for the management of acute musculoskeletal disorders. A phased withdrawal of carisoprodol from the UK market will take place.Meprobamate is closely related to carisoprodol and has a similar balance of risks and benefits. The MHRA is therefore exploring a phased withdrawal of this medicine in the UK

In the January 2008 issue of drug safety update (a stop press article) announced the recent European review of carisoprodol for which the Committee for Medicinal Products for Human Use (CHMP) concluded that the risks of treatment outweigh the benefits. This review was triggered by concerns from the Norwegian Medical Agency that carisoprodol was associated with increased risk of abuse, addiction, intoxication, and psychomotor impairment.

The CHMP has recommended that all marketing authorisations for carisoprodol-containing products should be suspended throughout the European Union. It is anticipated that a decision by the European Commission to ratify the CHMP decision will follow in the near future. A key feature of the CHMP opinion is that there are safer alternatives to carisoprodol for the management of acute musculoskeletal disorders where a muscle relaxant is required; 1 such alternative is a benzodiazepine.

Evidence suggests that carisoprodol can be associated with a withdrawal syndrome. 1 Clinical features include anxiety, insomnia, muscle twitching, and hallucinations, and are thought to be due to withdrawal of meprobamate—the main active metabolite of carisoprodol. When a patient may be physically dependent on carisoprodol, a gradual decrease in dose is required (which might take several weeks for those on high doses). If a withdrawal syndrome occurs, benzodiazepines are recommended in the short term; antipsychotics and antidepressants have also been used.

The MHRA is working with the UK Marketing Authorisation Holder (Forest Laboratories UK Ltd) to achieve a planned withdrawal of carisoprodol from the UK market. The European Commission’s decision may be issued before complete withdrawal of carisoprodol in the UK (particularly because there are patients who are physically dependent on the medicine). In these circumstances, essential supply will be possible on a named patient basis.

Advice for healthcare professionals includes:

  • the UK Marketing Authorisation for carisoprodol is to be suspended
  • treatment with carisoprodol should not be started
  • carisoprodol is associated with a withdrawal syndrome
  • when a patient may be physically dependent on carisoprodol, a gradual decrease in dose is required (which might take several weeks for those on high doses)
  • carisoprodol should not be stopped suddenly
  • if a withdrawal syndrome occurs, benzodiazepines are recommended in the short term; antipsychotics and antidepressants have also been used

Meprobamate

Meprobamate is a carbamate used for short-term treatment of anxiety states or musculoskeletal disorders where, in either case, there is muscle tension or painful muscle spasm.

Meprobamate shares many of the risks associated with barbiturates, including dependence and withdrawal, and has therefore been mainly superseded by relatively safer medicines. Meprobamate is the main active metabolite of carisoprodol, and the conclusions of the recent European review of carisoprodol are pertinent to meprobamate.

Considering that there are safer alternative medicines to meprobamate on the market, there are risks of dependence, withdrawal, abuse, and other undesirable effects associated with meprobamate; and the outcome of the European review of carisoprodol is negative, the balance of benefits and risks for meprobamate-containing products is no longer favourable.

MHRA is in discussion with the 3 UK marketing authorisation holders for meprobamate-containing products about a phased withdrawal from the UK market. Further details will be provided in due course.

Advice for healthcare professionals includes:

  • treatment with meprobamate should not be started
  • further information about this medicine will be provided in due course

More information

Martindale: The Complete Drug Reference for full information about meprobamate

Article citation: Drug Safety Update Feb 2008; Vol 1, Issue 7: 5

  1. Reeves RR, et al. Pharmacotherapy 2007; 27: 1462–66

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