A Cochrane review included 3 studies. Dichlorphenamide (DCP) produced a statistically significant improvement in attack rate and severity-weighted attack rate compared to placebo in patients with hypokalemic periodic paralysis (n=34 with adequate attack rate data). Similarly, DCP produced statistically significant improvent compared to placebo in respective attack rates in patients with hyperkalemic periodic paralysis (n=16 with adequate attack rate data). In patients with hypokalemic periodic paralysis, muscle strength was improved by both acetazolamide (1 trial, n=8) and pinacidil, a potassium channel opener (1 trial, n=12, 2 of the 4 patients with paralysis benefitted).
Comment: The quality of evidence is downgraded by imprecise results (few patients).