Overview

On 7 October 2013, orphan designation (EU/3/13/1189) was granted by the European Commission to Agenzia Industrie Difesa-Stabilimento Chimico Farmaceutico Militare, Italy, for mexiletine hydrochloride for the treatment of myotonic disorders.

Myotonic disorders are a group of inherited muscle disorders where muscles are slow to relax after contraction. The slow relaxation of the muscles causes symptoms such as stiffness and pain.

Myotonic disorders are caused by abnormalities in the ion channels, tiny pores in the muscle cells that control the passage of charged particles (ions) such as sodium or chloride and play a key role in the contraction and relaxation of muscles. When a muscle is affected by a myotonic disorder, these ion channels do not function properly. This dysfunction affects the ability of a muscle to relax after it has contracted. Until relaxation can properly occur, the muscles remain stiff and unusable.

Myotonic disorders are long-term debilitating due to the pain and muscle stiffness, which are associated with frequent falls and disability.

At the time of designation, myotonic disorders affected approximately 2 in 10,000 people in the European Union (EU). This was equivalent to a total of around 102,000 people*, and is below the ceiling for orphan designation, which is 5 people in 10,000. This is based on the information provided by the sponsor and the knowledge of the Committee for Orphan Medicinal Products (COMP).


*Disclaimer: For the purpose of the designation, the number of patients affected by the condition is estimated and assessed on the basis of data from the European Union (EU 28), Norway, Iceland and Liechtenstein. This represents a population of 512,200,000 (Eurostat 2013).

At the time of the orphan designation, mexiletine hydrochloride was authorised in France to treat myotonic disorders.

The sponsor has provided sufficient information to show that mexiletine hydrochloride might be of significant benefit for patients with myotonic disorders because the medicine has been in short supply in the EU and the orphan designation may encourage it to be made more widely available. This assumption will need to be confirmed at the time of marketing authorisation, in order to maintain the orphan status.

Mexiletine hydrochloride is a known antiarrhythmic medicine (medicine used to restore normal heart rhythm). It works by blocking ion channels for sodium ions in the muscle cells. These sodium channels play a role in the contraction and relaxation of muscles and by blocking them, the medicine helps to reduce the rate of contractions as well as the stiffness that occurs when the contractions are prolonged.

The effects of mexiletine hydrochloride have been evaluated in experimental models and in patients.

At the time of submission, mexiletine hydrochloride was authorised in France for myotonic disorders. Orphan designation of mexiletine hydrochloride had been granted in the EU for the myotonic disorder non-dystrophic myotonia and in the United States for the myotonic disorders myotonia and paramyotonia congenita.

In accordance with Regulation (EC) No 141/2000 of 16 December 1999, the COMP adopted a positive opinion on 4 September 2013 recommending the granting of this designation.

  • the seriousness of the condition;
  • the existence of alternative methods of diagnosis, prevention or treatment;
  • either the rarity of the condition (affecting not more than 5 in 10,000 people in the EU) or insufficient returns on investment.

Designated orphan medicinal products are products that are still under investigation and are considered for orphan designation on the basis of potential activity. An orphan designation is not a marketing authorisation. As a consequence, demonstration of quality, safety and efficacy is necessary before a product can be granted a marketing authorisation.

EU/3/13/1189: Public summary of opinion on orphan designation: Mexiletine hydrochloride for the treatment of myotonic disorders

Key facts

Active substance
Mexiletine hydrochloride
Intended use
Treatment of myotonic disorders
Orphan designation status
Positive
EU designation number
EU/3/13/1189
Date of designation
Sponsor

Agenzia Industrie Difesa-Stabilimento Chimico Farmaceutico Militare
Via XX Settembre 123/A
00187 Rome
Italy
Tel. +39 06 4990 3723
Fax +39 055 425 0568
E-mail: fiorentino.capozzoli@iss.it

Review of designation

The Committee for Orphan Medicinal Products reviews the orphan designation of a product if it is approved for marketing authorisation.

EMA list of opinions on orphan medicinal product designation

EMA publishes information on orphan medicinal product designation adopted by the Committee for Orphan Medicinal Products (COMP) on the IRIS online platform:

Patients' organisations

For contact details of patients’ organisations whose activities are targeted at rare diseases, see:

  • Orphanet, a database containing information on rare diseases, which includes a directory of patients’ organisations registered in Europe.

  • European Organisation for Rare Diseases (EURORDIS), a non-governmental alliance of patient organisations and individuals active in the field of rare diseases.

EU register of orphan medicines

The list of medicines that have received an orphan designation in the EU is available on the European Commission's website:

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