ABSTRACT
Objective: The aim of our study was to evaluate the long-term efficacy and safety of mexiletine in 112 patients affected by genetically confirmed non-dystrophic myotonias. The study was performed at the Neurophysiologic Division of Fondazione Policlinico Universitario A. Gemelli Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), Rome and the Children's Hospital Bambino Gesù, Rome. Methods: The treatment was accepted by 59 patients according to clinical severity, individual needs, and concerns about a chronic medication. Forty-three patients were affected by recessive congenita myotonia, 11 by sodium channel myotonia, and five by dominant congenital myotonia. They underwent clinical examination before and after starting therapy, and Electromyography (EMG). A number of recessive myotonia patients underwent a protocol of repetitive nerve stimulations, for detecting and quantifying the transitory weakness, and a modified version of the Timed Up and Go test, to document and quantify the gait impairment. Results: Treatment duration ranged from 1 month to 20 years and the daily dosages in adults ranged between 200 and 600 mg. No patient developed cardiac arrhythmias causing drug discontinuation. Mexiletine was suspended in 13 cases (22%); in three patients, affected by Sodium Channel myotonia, because flecainide showed better efficacy; in one patient because of a gastric cancer antecedent treatment; in four patients because of untreatable dyspepsia; and five patients considered the treatment not necessary. Conclusions: In our experience, mexiletine is very useful and not expensive. We did not observe any hazarding cardiac arrhythmias. Dyspepsia was the most frequent dose-limiting side effect.
ABSTRACT
According to the Regulation (EC) N. 141/2000 of the European Parliament and of the Council, rare diseases are life-threatening or chronically debilitating conditions, affecting no more than 5 in 10 000 persons in the European Community. It is estimated that between 6000 to 8000 distinct rare diseases affect up to 6% of the total EU population. Therefore, these conditions can be considered rare if taken individually but they affect a significant proportion of the European population when considered as a single group. Several initiatives have been undertaken at international, European and national level to tackle public health as well as research issues related to the prevention, diagnosis, treatment and surveillance of these diseases. The development of innovative and effective medical products for their diagnosis and treatment is frequently hampered by several factors, including the limited knowledge of their natural history, the difficulties in setting up clinical studies due to the limited numbers of patients affected by a specific disease, the weak interest of sponsors due to the restricted market opportunities. Therefore, incentives and other facilitations have been adopted in many parts of the world, including in the EU, in order to facilitate the development and commercialization of diagnostic tools and treatments devoted to rare diseases. This paper illustrates mainly the European initiatives and will discuss the problematic and controversial aspects surrounding orphan drugs. Finally, activities and measures adopted in Italy are presented.
