Phenytoin (PHT), sold under the brand name Dilantin among others, Blood levels can be measured to determine the proper dose. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Phenytoin is available as a generic medication and usually not too expensive. The wholesale cost in the developing world is between US$0.003 and US$0.15 per dose. A month of treatment is about US$30 in the United States. In 2016 it was the 201st most prescribed medication in the United States with more than 2 million prescriptions.