Phase III Randomized, Double-Blind, Placebo-Controlled Study of Dichlorphenamide for Periodic Paralyses and Associated Sodium Channel Disorders

PROTOCOL ENTRY CRITERIA: --Disease Characteristics-- Hypokalemic periodic paralysis Typical clinical profile Normal serum thyroxine Hypokalemia during spontaneous or glucose-induced paralytic attack in subject or affected family member Periodic paralysis associated with sodium channel 17q alpha-subunit, e.g.: * Hyperkalemic periodic paralysis with or without myotonia * Paramyotonia congenita with periodic paralysis Distinct, regular episodes of weakness at least once a week and no more than 3 times a day No history of worsening symptoms with carbonic anhydrase inhibitor No history of life-threatening weakness episodes prior to treatment No atypical periodic paralysis without demonstrable 17q alpha-subunit defect --Prior/Concurrent Therapy-- No requirement for the following agents, unless for periodic paralysis: * Diuretics * Antiepileptics * Antiarrhythmics * Magnesium supplements * Steroids * Calcium supplements * Beta-blockers * Potassium supplements * Calcium channel blockers --Patient Characteristics-- Hepatic: No hepatic disease Renal: * No renal failure * No nephrolithiasis Cardiovascular: * No heart disease * No cardiac arrhythmia Pulmonary: No restrictive or obstructive lung disease Other: * No active thyroid disease * No pregnant women