ABSTRACT
Foscarnet, also known as phosphonoformate, usually abbreviated as FOS and occasionally abbreviated as PFA, is an organic analog of inorganic pyrophosphate. Foscarnet is a broad inhibitor of viral DNA polymerases, including both DNA-dependent and RNA-dependent enzymes (the latter usually termed reverse transcriptases). Consequently it is active against DNA viruses, including herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), cytomegalovirus (CMV), varicella-zoster virus (VZV), Epstein-Barr virus (EBV), and human herpesviruses types 6 and possibly 8 (HHV-6 and HHV-8) (Helgstrand et al., 1978; Mesri et al., 1996; Wagstaff and Bryson, 1994). In addition, it inhibits the reverse transcriptases of hepadnaviruses, including human and duck hepatitis B viruses, and primate immunodeficiency viruses such as HIV-1 and HIV-2 (Sandstrom et al., 1985; Sarin et al., 1985). It also interferes with mRNA synthesis of influenza viruses (Stridh et al., 1979; Oberg, 1983; Strid et al., 1989). Clinically, it is used to treat herpesvirus infections, especially those resistant to the usual antiviral drugs and, almost never, for treatment of multidrug-resistant HIV infection.
