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Carisoprodol

Volume 455: debated on Monday 8 January 2007

To ask the Secretary of State for Health (1) when the Medicines and Healthcare Products Regulatory Agency expects to publish its updated assessment on carisoprodol; (106272)

(2) when the Medicines and Healthcare Products Regulatory Agency expects to update the Patient Information Leaflet for carisoprodol;

(3) when her Department was first notified of possible side effects of carisoprodol linked to metabolism;

(4) what guidelines she issues on the length of time the Medicines and Healthcare Products Regulatory Agency should take to re-evaluate a drug where concerns have been raised about it;

(5) how many patients have reported side effects from using carisoprodol not listed on the patient information leaflet;

(6) what research (a) her Department and (b) the Medicines and Healthcare Products Regulatory Agency has commissioned on the side effects of carisoprodol.

Carisoprodol, brand name Carisoma, is a muscle relaxant authorised as an add-on therapy to the symptomatic treatment of acute musculoskeletal disorders associated with muscle spasm. Clinical trials carried out by the marketing authorisation holder for carisoprodol were evaluated at the time of licensing to ensure that it met appropriate standards of safety, quality and efficacy to justify its use as a muscle relaxant. Full guidance on prescribing and the use of carisoprodol, including possible side- effects, is provided in the product information for prescribers, the Summary of Product Characteristics, and the patient information leaflet.

Since the marketing of carisoprodol, although no formal research has been commissioned, the Commission on Human Medicines (CHM) and the Medicines and Healthcare products Regulatory Agency (MHRA) have kept under review its safety in routine clinical practice.

Up to 29 November 2005, a total of 31 reports of suspected adverse drug reactions (ADRs) have been received in association with carisoprodol. The majority of these (28 out of 31 reports) were received prior to 1982. Of the 31 reports, a total of 20 reports describe suspected side-effects from using carisoprodol that are not listed in the patient information leaflet. Urticaria, three reports, and chills, two reports, are the only unlisted suspected side-effects associated with carisoprodol reported in more than one patient. It is important to note that a report of a suspected ADR does not necessarily mean that the drug caused it.

In June 2005 the MHRA was alerted to concerns about the effect that an individual’s genetic makeup may have on how they metabolise carisoprodol and that this may have implications for the likelihood of experiencing potential side-effects associated with its use. Following a review of the available data, the Summary of Product Characteristics and the patient Information leaflet have been updated to reflect these new data and to add a warning that patients who are so called “poor metabolisers” for a specific enzyme, Cytochrome 2C19, involved in the metabolism of carisoprodol may be at an increased risk of certain side-effects such as drowsiness.

In parallel with this action, the overall balance of risks and benefits of carisoprodol has been raised at European level. The MHRA in conjunction with its European counterparts is currently re-evaluating the risk and benefits of carisoprodol and considering what implications this may have for its clinical use. As soon as the European review is completed the results will be made publicly available.

The use of carisoprodol in the UK is limited and the British National Formulary, a joint publication of the British Medical Association and the Royal Pharmaceutical Society of Great Britain, advises doctors that carisoprodol may not be considered as a drug of first choice although its use may be justifiable in certain circumstances.

The length of time for the Medicines and Healthcare products Regulatory Agency (MHRA) to re-evaluate a drug by completing of a risk: benefit review depends on the public health impact of the safety or efficacy concerns and is commensurate with the need for a thorough evaluation of the available data.