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

ten Hove, Martin W. MD; Friedman, Deborah I. MD; Patel, Anil D. MD; Irrcher, Isabella PhD; Wall, Michael MD; McDermott, Michael P. PhDfor the NORDIC Idiopathic Intracranial Hypertension Study Group

Journal of Neuro-Ophthalmology: March 2016 - Volume 36 - Issue 1 - p 13–19
doi: 10.1097/WNO.0000000000000322
Original Contribution

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.

Department of Ophthalmology (MWtH, II), Queen's University and Hotel Dieu Hospital, Kingston, Ontario, Canada; Departments of Neurology and Neurotherapeutics and Ophthalmology (DIF), University of Texas Southwestern Medical Center, Dallas, Texas; Department of Ophthalmology (ADP), Dean McGee Eye Institute, University of Oklahoma, Oklahoma City, Oklahoma; Department of Neurology (MW), University of Iowa, Iowa City, Iowa; and Department of Biostatistics and Computational Biology (MPM), University of Rochester, Rochester, New York.

Address correspondence to Martin W. ten Hove, MD, Queen's University and Hotel Dieu Hospital, Department of Ophthalmology, 166 Brock Street, Kingston, Ontario, K7L 5G2; E-mail:

Funding Source: U10 EY017281-01A1, U10 EY017387-01A.

The authors report no conflicts of interest.

© 2016 by North American Neuro-Ophthalmology Society