Source: FDA, National Drug Code (US) Revision Year: 2020
Dichlorphenamide is a carbonic anhydrase inhibitor. However, the precise mechanism by which dichlorphenamide exerts its therapeutic effects in patients with periodic paralysis is unknown.
The pharmacokinetic properties of dichlorphenamide after oral absorption are not known.
Studies to assess the carcinogenic potential of dichlorphenamide have not been conducted.
Studies to assess the genotoxicity of dichlorphenamide have not been conducted.
Studies to assess the effects of dichlorphenamide on fertility have not been conducted.
The efficacy of KEVEYIS was evaluated in two clinical studies, Study 1 and Study 2.
Study 1 was a 9-week, double blind, placebo-controlled multi-center study. Study 1 consisted of two substudies: a substudy in patients with hypokalemic periodic paralysis (n=44), and a substudy in patients with hyperkalemic periodic paralysis (n=21). The primary efficacy endpoint in both substudies was the average number of self-reported attacks of muscle weakness per week over the final 8 weeks of the trial. Withdrawal from the study for acute severe worsening was also assessed as an endpoint.
In Study 1, the dose of KEVEYIS was 50 mg b.i.d. for treatment-naïve patients. Patients already on dichlorphenamide prior to the study continued on the same dose while on KEVEYIS during the study. In patients taking acetazolamide prior to the study, the dose of KEVEYIS was set at 20% of the acetazolamide dose. Dose reduction for tolerability was permitted.
In the hypokalemic periodic paralysis substudy, median age of patients was 45 years and 73% of patients were male. Patients treated with KEVEYIS (n=24) had 2.2 fewer attacks per week than patients (n=20) treated with placebo (p=0.02). None of the patients randomized to KEVEYIS reached the endpoint of acute worsening, vs. five patients randomized to placebo. The mean dose of KEVEYIS at Week 9 was 94 mg/day.
In the Hyperkalemic Periodic Paralysis substudy, median age of patients was 43 years and 43% of patients were male. During the double-blind treatment period, patients treated with KEVEYIS (n=12) had 3.9 fewer attacks per week than patients (n=9) treated with placebo (p=0.08). None of the patients randomized to KEVEYIS reached the endpoint of acute worsening, vs. two patients randomized to placebo. The mean dose of KEVEYIS at Week 9 was 82 mg/day.
Study 2 was a 35-week, double blind, placebo-controlled, multi-center, two-period crossover study. Study 2 also consisted of two substudies: a substudy in a substudy in patients with hypokalemic periodic paralysis (n=42), and a substudy in patients with hyperkalemic periodic paralysis (n=31), including patients with Paramyotonia Congenita. The primary endpoint in the hypokalemic periodic paralysis substudy was the incidence of acute intolerable worsening (based on attack frequency or severity) necessitating withdrawal. The primary endpoint in the hyperkalemic periodic paralysis substudy was the average number of self-reported attacks of muscle weakness per week. Dosing was determined similarly to Study 1.
In the hypokalemic periodic paralysis substudy, mean age of patients was 38 years and 79% of patients were male. Acute intolerable worsening was observed in 2 patients on KEVEYIS vs. 11 patients on placebo (p=0.02). The mean dose of KEVEYIS at the end of the study was 96 mg/day.
In the hyperkalemic periodic paralysis substudy, mean age of patients was 37 years and 79% of patients were male. Patients treated had 2.3 fewer attacks per week on KEVEYIS than on placebo (p=0.006). The mean dose of KEVEYIS at the end of the study was 73 mg/day.
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