oral absorption. Tenofovir disoproxil was approved in the U.S. in 2001, for the treatment of HIV, and in 2008, for the treatment of chronic hepatitis B. Drug forms Tenofovir disoproxil can be taken by mouth and is sold under the brand name Viread, among others. Tenofovir disoproxil is a pro-drug form of tenofovir phosphonate, which is liberated intracellularly and converted to tenofovir disphophate. It is marketed by Gilead Sciences (as the fumarate, abbreviated TDF). Tenofovir disoproxil is also available in pills which combine a number of antiviral drugs into a single dose. Well-known combinations include Atripla (tenofovir disoproxil/emtricitabine/efavirenz), Complera (tenofovir disoproxil/emtricitabine/rilpivirine), Stribild (tenofovir disoproxil/emtricitabine/elvitegravir/cobicistat), and Truvada (tenofovir disoproxil/emtricitabine). Gilead has created a second pro-drug form of the active drug, tenofovir diphosphate, called tenofovir alafenamide. It differs from tenofovir disoproxil due to its activation in the lymphoid cells. This allows the active metabolites to accumulate in those cells, leading to lower systemic exposure and potential toxicities. References External links Carbonate esters Gilead Sciences Hepatotoxins Isopropyl esters Microbicides Nucleoside analog reverse transcriptase inhibitors Prodrugs Purines World Health Organization essential medicines Wikipedia medicine articles ready to translate Czech inventions