Neuropsychiatric effects As of 2016 the mechanism of efavirenz' neuropsychiatric adverse effects was not clear. Efavirenz appears to have neurotoxicity, possibly by interfering with mitochondrial function, which may in turn possibly be caused by inhibiting creatine kinase but also possibly by disrupting mitochondrial membranes or by interfering with nitric oxide signalling. Some neuropsychiatric adverse effects may be mediated through cannabinoid receptors, or through activity at the 5-HT2A receptor, but efavirenz interacts with many CNS receptors, so this is not clear. The neuropsychiatric adverse effects are dose-dependent. Chemical properties Efavirenz is chemically described as (4S)-6-chloro-4-(2-cyclopropylethynyl)-4-(trifluoromethyl)-1H-3,1-benzoxazin-2-one. Its empirical formula is C14H9ClF3NO2. Efavirenz is a white to slightly pink crystalline powder with a molecular mass of 315.68 g/mol. It is practically insoluble in water (<10 µg/mL). History Efavirenz was approved by the FDA on 21 September 1998. On 17 February 2016, the FDA approved the generic tablet formulation to be produced by Mylan. In late 2018, Thailand's Government Pharmaceutical Organization (GPO) announced that it will produce efavirenz after receiving WHO approval. Efavirenz code name is DMP 266, discovered by Du pont Pharma. European countries are set to receive the license for manufacturing of Efavirenz in May 1999. Society and culture Pricing information A one-month supply of 600 mg tablets costs approximately US$1,010 in July 2016. In 2007, Merck provided Efavirenz in certain developing countries and countries largely affected by HIV for about US$0.65 per day. Some emerging countries have opted to purchase Indian generics. In Thailand, a one-month supply of efavirenz + Truvada, as of June 2012, cost 2,900 baht (), and there is a social program for patients who cannot afford the medication. Thailand will produce efavirenz domestically. Its Government Pharmaceutical Organization product costs 180 baht per bottle of thirty 600 mg tablets. The imported version in Thailand retails for more than 1,000 baht per bottle. GPO will devote 2.5 percent of its manufacturing capacity to make 42 million efavirenz pills in 2018, allowing it to serve export markets as well as domestic. The Philippines alone will order about 300,000 bottles of efavirenz for 51 million baht. In South Africa, a license has been granted to generics giant Aspen Pharmacare to manufacture, and distribute to sub-Saharan Africa, a cost-effective antiretroviral drug. Recreational use Abuse of efavirenz by crushing and smoking the tablets for supposed hallucinogenic and dissociative effects has been reported in South Africa, where it is used in a mixture known