The present Invention relates to (2R, 5S, 13ar) - 7.9 - [- 10 - (2,4,6 - trifluorobencil) Carbamoyl) - 2,3,4,5,7,9,13, 13th - octahidro - 2.5 - metanopirido [1 ', 2': pirazino 4.5] [2,1-b] [1.3] oxazepin - 8 - olato Sodium Form I, their use, and Methods for treating or Preventing an HIV infection.La presente invención de se relaciona con (2R, 5S, 13aR)-7,9-dioxo-10-((2,4,6- trifluorobencil)carbamoil)-2,3,4,5,7,9,13, 13a-octahidro-2,5-metanopirido[1', 2':4,5]pirazino [2,1-b] [1,3] oxazepin-8-olato de sodio Forma I, su uso y métodos para tratar o prevenir una infección por VIH.