When acetazolamide, an agent used to treat hyperkalemic periodic paralysis, was inadvertently found to relieve a patient with the hypokalemic variety, he and another patient were observed to compare this agent with conventional therapy. Well tolerated doses of acetazolamide, 375 to 500 mg daily, eliminated severe attacks and were much more effective than potassium or spironolactone. Preliminary results in five additional patients with hypokalemic periodic paralysis indicated that only three are improved. Two have not benefited.

It seems paradoxical that acetazolamide is prophylactic for both hypokalemic and hyperkalemic periodic paralysis. The mechanism of its action in the hypokalemic variety is not known. It did not appear to affect serum potassium, total body potassium, total body sodium, blood pH, nor was the agent shown to affect muscle excitability directly.