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