Drug Passes First Trial -- After Wide Use. By Michael Smith, North American Correspondent, MedPage Today. A drug widely used for a rare neurological condition that mainly affects overweight women -- pseudotumor cerebri -- improves vision and leads to weight loss, researchers reported. In the first randomized trial of acetazolamide (Diamox), the drug led to a significant improvement in vision in patients with the condition, also known as idiopathic intracranial hypertension, or IIH, according to Michael Wall, MD, of the University of Iowa Hospitals and Clinics in Iowa City. But the clinical significance of the improvement remains to be determined, Wall and colleagues concluded in the April 23/30 issue of the Journal of the American Medical Association. The symptoms of IIH mimic those of a brain tumor, including headaches, dizziness, increased intracranial pressure, and vision impairment, but there is no tumor. The condition affects about one in 100,000 people, mainly overweight women of childbearing age. Acetazolamide, which lowers intracranial pressure, has been used as a pharmacological treatment for years, the authors noted, but there has never been a randomized trial to demonstrate that it is beneficial. To fill the gap, they randomly assigned 161 women and four men to get acetazolamide or matching placebo for 6 months, along with a low-sodium diet for all participants. All participants had mild vision impairment -- a perimetric mean deviation between minus two and minus seven decibels (dB), where a larger negative number indicates greater vision loss. The primary endpoint was the change over the treatment period in perimetric mean deviation (a measure of global visual field loss compared with age-corrected normal values) in the most affected eye. A more intuitive endpoint would have been intracranial pressure itself, commented Jonathan Horton, MD, of the University of California San Francisco. But, in an accompanying editorial, he noted that such a measure is invasive, requiring a lumbar puncture, and the results are unreliable. There is an urgent need for a reliable, noninvasive technique to measure human intracranial pressure, Horton argued. But until such a method is available, doctors must rely on examining the optic fundi for the presence of optic disc swelling, or papilledema, he wrote. In the trial, Wall and colleagues reported, acetazolamide significantly improved vision: Among the 86 patients in the acetazolamide arm the average improvement in perimetric mean deviation was 1.43 dB, from -3.53 dB at baseline to -2.10 dB after 6 months of treatment. Among the 79 placebo patients, the average change was 0.71 dB, from -3.53 dB to -2.82 dB. The difference between the arms was significant at P=0.05. Patients getting the drug also had significantly greater improvements in papilledema grade and vision-related quality of life, at P
Posted on: Sat, 07 Jun 2014 06:02:55 +0000
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