Dichlorphenamide: A Review in Primary Periodic Paralyses.

Area of Science:

• Neurology
• Pharmacology

Background:

• Primary hyperkalaemic and hypokalaemic periodic paralyses are rare genetic disorders.
• Current treatment options for periodic paralyses are limited.

Purpose of the Study:

• To evaluate the efficacy and safety of oral dichlorphenamide for treating primary hyperkalaemic and hypokalaemic periodic paralyses.
• To assess the long-term effectiveness and tolerability of dichlorphenamide.

Main Methods:

• Four randomized, double-blind, placebo-controlled, phase III trials (parallel-group and crossover) were conducted.
• Open-label extension trials assessed long-term efficacy and safety over 52 weeks.

Main Results:

• Dichlorphenamide significantly reduced paralytic attack rates in hypokalaemic periodic paralysis (eightfold lower).
• In hyperkalaemic periodic paralysis, attack rates were lower with dichlorphenamide (fivefold lower in one trial).
• Sustained efficacy and good tolerability were observed during long-term treatment.

Conclusions:

• Dichlorphenamide is an effective and well-tolerated treatment for primary hyperkalaemic and hypokalaemic periodic paralyses.
• As the first approved agent for this indication in the USA, dichlorphenamide offers a valuable therapeutic option.