Foscarnet (foscavir), the pricey drug for cytomegalovirus (CMV) and other herpes viruses (like that pesky genital variety), had its rise to stardom halted by the hassle of a daily IV drip—and nasty side effects (kidney problems, fever, rash, dizziness). But it’s still giving the potentially blinding CMV a run for its money—and a few clever clinicians say salvage combos often perform better with foscarnet on board. While docs may prescribe the med for CMV or drug-resistant herpes (HSV), their patients get the benefit of an extra HIV-fighting machine.
New York City HIV pro Trip Gulick, MD, explains that foscarnet may block the part of HIV reproduction that escapes the nukes. HIV, a mouse in a maze, tries to evade a triple or quadruple combo—and foscarnet stands in the only remaining exit.
“I know a few docs who’ve been doing this for decades,” says Project Inform’s Martin Delaney. “They bring in Foscavir for people who’ve failed all else or have just one drug left.” Most doctors interviewed would not suggest using foscarnet for its antiretroviral powers alone. Both Gulick and Howard Grossman, MD, say it’s too hard to administer—and its side effects too hard to take—to use as a salvage drug, unless it’s needed to treat CMV or HSV.
Meanwhile, Gulick has a patient with resistant HIV whose viral load fell dramatically after starting a new combo—plus Foscavir for acyclovir-resistant herpes. His virus rebounded when the foscarnet, but not the HIV meds, was stopped. “This doesn’t prove that foscarnet caused the drop in viral load,” Gulick cautions, “but it is interesting.”