A form of hemifumarate 9 - [(R) - 2 - [[(S) - [(S) - 1 - (isopropoxicarbonil) ethyl] amino] propyl] fenoxifosfinil] methoxy] adenine (tenofovir alafenamida) and Antiviral Therapy that uses hemifumarate tenofovir alafenamida Therapies (e.g., anti anti HIV and HBV).Una forma de hemifumarato de 9-[(R)-2-[[(S)-[[(S)-1-(isopropoxicarbonil)etil]-amino]fenoxifosfinil]metoxi]propil]adenina (tenofovir alafenamida) y la terapia antiviral que utiliza hemifumarato de tenofovir alafenamida (p.ej., las terapias anti-HIV y anti-HBV).