Effects of 3-4 diaminopyridine (DAP) in motor neuron diseases.

OBJECTIVE

To study the safety of 3-4 diaminopyridine (DAP) in patients with motor neuron diseases and to examine its efficacy in reducing muscle fatigue and weakness and in improving objective parameters of muscle function.

DESIGN

Assessments of safety included a questionnaire of symptoms, clinical examination, blood testing, and electrocardiography at each visit; efficacy was assessed by subjective scores of fatigue and weakness; an Amyotrophic Lateral Sclerosis Functional Rating Scale and functional ability scores, including timed verbal scores; manual muscle testing; grip dynamometry; pulmonary function tests; timed functional tests; and electrophysiological studies.

PARTICIPANTS

Thirteen subjects with amyotrophic lateral sclerosis and seven subjects with only a lower motor neuron syndrome.

MAIN OUTCOMES: Assess tolerability of DAP and determine if there was symptomatic improvement of muscle fatigue. SECONDARY OUTCOME: To determine the effects of DAP on objective parameters of muscle function.

RESULTS

The drug was well tolerated with only four subjects reporting tingling of lips and fingers during the active drug period. The subjective scores for fatigue and weakness showed a mild improvement after 4 weeks on DAP compared with placebo. A significant benefit of DAP was also demonstrated in the timed verbal scores.

CONCLUSION

3-4 DAP appeared to be safe and produced subjective benefit in motor neuron diseases. The drug could be added for symptomatic treatment in these diseases. Larger studies are necessary to demonstrate efficacy.