When to switch depends on what you can switch to.
Huff
Bob
B
D019380:Anti-HIV Agents / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D010818:Practice Patterns, Physicians'; D019562:Viral Load
D019380:Anti-HIV Agents