Mexiletine for symptoms and signs of myotonia in nondystrophic myotonia: a randomized controlled trial.
JAMA
; 308(13): 1357-65, 2012 Oct 03.
Article
em En
| MEDLINE
| ID: mdl-23032552
ABSTRACT
CONTEXT Nondystrophic myotonias (NDMs) are rare diseases caused by mutations in skeletal muscle ion channels. Patients experience delayed muscle relaxation causing functionally limiting stiffness and pain. Mexiletine-induced sodium channel blockade reduced myotonia in small studies; however, as is common in rare diseases, larger studies of safety and efficacy have not previously been considered feasible. OBJECTIVE:
To determine the effects of mexiletine for symptoms and signs of myotonia in patients with NDMs. DESIGN, SETTING, ANDPARTICIPANTS:
A randomized, double-blind, placebo-controlled 2-period crossover study at 7 neuromuscular referral centers in 4 countries of 59 patients with NDMs conducted between December 23, 2008, and March 30, 2011, as part of the National Institutes of Health-funded Rare Disease Clinical Research Network. INTERVENTION Oral 200-mg mexiletine or placebo capsules 3 times daily for 4 weeks, followed by the opposite intervention for 4 weeks, with 1-week washout in between. MAIN OUTCOMEMEASURES:
Patient-reported severity score of stiffness recorded on an interactive voice response (IVR) diary (scale of 1 = minimal to 9 = worst ever experienced). Secondary end points included IVR-reported changes in pain, weakness, and tiredness; clinical myotonia assessment; quantitative measure of handgrip myotonia; and Individualized Neuromuscular Quality of Life summary quality of life score (INQOL-QOL, percentage of maximal detrimental impact).RESULTS:
Mexiletine significantly improved patient-reported severity score stiffness on the IVR diary. Because of a statistically significant interaction between treatment and period for this outcome, primary end point is presented by period (period 1 means were 2.53 for mexiletine and 4.21 for placebo; difference, -1.68; 95% CI, -2.66 to -0.706; P < .001; period 2 means were 1.60 for mexiletine and 5.27 for placebo; difference, -3.68; 95% CI, -3.85 to -0.139; P = .04). Mexiletine improved the INQOL-QOL score (mexiletine, 14.0 vs placebo, 16.7; difference, -2.69; 95% CI, -4.07 to -1.30; P < .001) and decreased handgrip myotonia on clinical examination (mexiletine, 0.164 seconds vs placebo, 0.494 seconds; difference, -0.330; 95% CI, -0.633 to -0.142; P < .001). The most common adverse effect was gastrointestinal (9 mexiletine and 1 placebo). Two participants experienced transient cardiac effects that did not require stopping the study (1 in each group). One serious adverse event was determined to be not study related.CONCLUSION:
In this preliminary study of patients with NDMs, the use of mexiletine compared with placebo resulted in improved patient-reported stiffness over 4 weeks of treatment, despite some concern about the maintenance of blinding. TRIAL REGISTRATION clinicaltrials.gov Identifier NCT00832000.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Mexiletina
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Antiarrítmicos
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Miotonia
Tipo de estudo:
Clinical_trials
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Diagnostic_studies
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Etiology_studies
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Prognostic_studies
Limite:
Adolescent
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Adult
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Aged
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article