Antiviral agents foscarnet

Nyberg G, Svalander C, Blohme I, Persson El. Tubulointerstitial nephritis caused by the antiviral agent foscarnet. Transplant Int 1989 2 223-227. 

Mechanism of Action. Foscarnet works somewhat like acyclovir and ganciclovir that is, foscarnet inhibits the DNA polymerase enzyme necessary for viral DNA replication. Foscarnet differs from these other antiviral drugs, however, in that it does not require phosphorylation (activation) by enzymes such as viral thymidine kinase. Certain strains of viruses are thymidine-kinase deficient, meaning that these viruses lack the enzyme needed to activate antiviral agents... 

The sites at which anti-HIV drugs may. in principle, act, are dealt with in detail under a main heading (see ANTIVIRAL agents). In summary, currently, of the drugs actually in use, a number are reverse transcriptase (enzyme) inhibitors (RTIs). Examples of nucleoside RTIs include zidovudine, didanosine and zalcitabine. Some non-nucleoside RTIs include foscarnet sodium, nevirapine, carbovir and TIBO analogues (some of these are at trial stage only). 

Acyclovir-resistant HSV has been isolated from patients with AIDS. The primary mechanism of resistance appears to be a deficiency in viral thymidine kinase. Strategies that have been employed for management of severe acyclovir-resistant HSV infections include increasing the dose of acyclovir, discontinuing acyclovir, and use of an alternative antiviral agent. Vidarabine and foscarnet, because they do not require phosphorylation by thymidine kinase, are examples of potential alternative agents. A randomized comparison of foscarnet and vidarabine indicated that foscarnet is more effective and associated with fewer adverse reactions than vidarabine. ... 

Antiviral Efficacy and Clinical Use. Foscarnet (Fos-cavir) is primarily given to treat CMV retinitis in patients with AIDS.6,24 This agent may also help control other infections in patients with a compromised immune system, including serious cytomegaloviral infections (pneumonia, gastrointestinal infections) and some herpesvirus infections (herpes simplex, varicella-zoster). 

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