Diclofenamide

Diclofenamide (or dichlorphenamide) is a sulfonamide and a carbonic anhydrase inhibitor of the "meta"-disulfamoylbenzene class.
Uses.
Diclofenamide was approved in the United States in 1958 as "Daranide" to treat glaucoma, Subsequently, it was found effective in cases of therapy-resistant epilepsy. In 2015, the medication was approved in the US under the name "Keveyis" as an orphan drug for the treatment of primary hypokalemic and hyperkalemic periodic paralysis.
Cost.
In 2001, diclofenamide had a U.S. list price of $50 for a bottle of 100 pills, and was approved for glaucoma. Merck discontinued diclofenamide when better glaucoma drugs were developed. In 2010, Sun Pharmaceutical Industries bought the rights. In 2015, the F.D.A. approved it as an orphan drug, with 7-year exclusive marketing rights, for periodic paralysis, which the company estimates affects 5,000 people in the U.S. In 2016, Strongbridge Biopharma acquired Sun, which raised the price to $15,001 for 100 pills. The cost of treatment would range from $109,500 to $219,000 a year. Sun gives the drug free to patients who don't have insurance.