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NICE likely to recommend mexiletine for treating the symptoms of myotonia in adults with non-dystrophic myotonic disorders

4 November 2021

NICE likely to recommend mexiletine for treating the symptoms of myotonia in adults with non-dystrophic myotonic disorders

We are delighted to learn today (4 November) that NICE has published its ‘final appraisal document’ recommending the use of mexiletine (Namuscla) as an option for treating the symptoms of myotonia in adults with non-dystrophic myotonic disorders.

What is mexiletine?

Mexiletine is a drug that works by blocking a kind of pore in the membrane of a cell, called a sodium channel. Treatments for the symptoms of myotonia in adults with non-dystrophic myotonic disorders already include imported mexiletine (which is not licensed in the UK), or other sodium channel blockers, if mexiletine is not suitable. However, NICE’s recommendation means that eligible patients in England would be able to access Namuscla (manufactured by a company called Lupin), the only brand of mexiletine with a UK marketing authorisation.

What are non-dystrophic myotonic disorders?

Non-dystrophic myotonic disorders are a group of extremely rare group of muscle disorders, in which voluntary muscles are slow to relax after movement. This problem occurs intermittently, though often on a daily basis. These disorders cause muscle stiffness (myotonia), pain, weakness and fatigue. They do not cause muscle wasting, but they can reduce mobility and the ability to complete daily activities. Mexiletine hydrochloride was found to significantly reduce muscle stiffness, when compared with placebo in a phase III clinical study.

What does today’s announcement mean?

In February, MDUK reported our disappointment when we learnt that mexiletine might not be recommended by NICE because of issues around cost effectiveness. Since then, we have been attending the NICE committee meetings and calling on NICE, Lupin and NHS England to overcome the barriers for a recommendation so that everyone who is eligible benefits from this treatment as soon as possible.

Today NICE has published a final appraisal document on mexiletine for treating the symptoms of myotonia in non-dystrophic myotonic disorders. This document has been sent to consultees for this appraisal who have 15 working days to consider whether they wish to appeal against it and/or notify NICE of any factual errors. Subject to any appeal, the document may be used as the basis for NICE’s guidance on the use of the appraised technology in the NHS in England. It is expected that the guidance will be published in early December.

We are pleased that everyone who is eligible should soon have access to this new treatment. Once the guidance has been published, our advice to adult patients in England, who believe they may be eligible for treatment, is to contact their physician.

Robert Burley, MDUK Director of Care, Communications and Support, said:

“Adults living with the condition have told us first-hand how much pain and disruption muscle stiffness causes them each day, but those symptoms improve when taking the drug. We’re delighted with today’s news that adults in England, who have non-dystrophic myotonic disorders, should soon have access to mexiletine (Namuscla), following NICE’s guidance.”

The Scottish Medicines Consortium had already approved mexiletine in Scotland in December 2020. You can find further information on their approval criteria here. The authorities in Wales and Northern Ireland generally follow NICE’s guidance, and we hope that adults with non-dystrophic myotonic disorders will soon be able to access the treatment there as well.

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