Safety and Tolerability of Acetazolamide in the Idiopathic Intracranial Hypertension Treatment Trial.

OBJECTIVE

To examine the tolerability and adverse events reported in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT).

METHODS

Randomized, double-masked, placebo-controlled clinical trial. Trial participants (n = 165) with mild visual loss concurrently receiving low-sodium weight-reduction diet plus the maximally tolerated dosage of acetazolamide (up to 4 g/d) or placebo for 6 months.

MAIN OUTCOMES MEASURES: adverse events (AEs), assessment of clinical and laboratory findings at study visits.

RESULTS

Thirty-eight of 86 participants randomized to the acetazolamide group (44.1%) tolerated the maximum allowed dosage of 4 g/d. The average time to achieve maximum study dosage in the acetazolamide group was 13 weeks (median 12 weeks; range 10-24 weeks). A total of 676 AEs (acetazolamide, n = 480; placebo, n = 196) and 9 serious AEs (acetazolamide, n = 6; placebo, n = 3) were reported. Notably, the percentages of participants reporting at least 1 AE in the nervous, gastrointestinal, metabolic, and renal organ systems were significantly higher in the acetazolamide group (P < 0.05). The odds of paresthesia (OR 9.82; 95% CI 3.87-27.82), dysgeusia (OR ∞; 95% CI 3.99-∞), vomiting and diarrhea (OR 4.11; 95% CI 1.04-23.41), nausea (OR 2.99; 95% CI 1.26-7.49) and fatigue (OR 16.48; 95% CI 2.39-702.40) were higher in the acetazolamide group than in the placebo group.

CONCLUSION

Acetazolamide appears to have an acceptable safety profile at dosages up to 4 g/d in the treatment of idiopathic intracranial hypertension. The majority of participants in the Idiopathic Intracranial Hypertension Treatment Trial were able to tolerate acetazolamide above 1 g/d for 6 months.