Foscarnet is the conjugate base of the chemical compound with the formula HO2CPO3H2. This phosphonic acid derivative is (marketed by AstraZeneca as foscarnet sodium under the trade name Foscavir®) is an antiviral medication used to treat herpes viruses, including cytomegalovirus (CMV) and herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2). It is particularly used to treat CMV retinitis. of the with the HOCPOH. This derivative is (marketed by as foscarnet under the trade name Foscavir®) is an used to treat , including (CMV) and viruses types 1 and 2 (HSV-1 and HSV-2). It is particularly used to treat .
Mechanism of action
Foscarnet is a structural mimic of the anion pyrophosphate that selectively inhibits the pyrophosphate binding site on viral DNA polymerases at concentrations that do not affect human DNA polymerases. Because foscarnet is not activated by thymidine kinase, it maintains activity in some viruses which have lost thymidine kinase activity to gain resistance to aciclovir or ganciclovir. Therefore, foscarnet is often used in aciclovir- or ganciclovir-resistant disease. However, acyclovir or ganciclovir resistant mutants with alterations in viral DNA polymerase may be resistant to foscarnet. that selectively inhibits the pyrophosphate binding site on viral at that do not affect human DNA polymerases. Because foscarnet is not activated by , it maintains activity in some viruses which have lost thymidine kinase activity to gain resistance to or . Therefore, foscarnet is often used in aciclovir- or ganciclovir-resistant disease. However, acyclovir or ganciclovir resistant mutants with alterations in viral DNA polymerase may be resistant to foscarnet.
Administration
Intravenous only only
Side effects
1. Nephrotoxicity - Increase in serum creatinine levels occurs on average in 45% of patients receiving foscarnet. Other nephrotoxic drugs should be avoided. Nephrotoxicity is usually reversible and can be reduced by dosage adjustment and adequate hydration.
2. Electrolyte distrubances - Changes in calcium, magnesium, potassium and phosphate levels occurs commonly and regular monitoring of electrolytes is necessary to avoid clinical toxicity.
3. Genital ulceration - Occurs more commonly in men and usually occurs during induction use of foscarnet. It is most likely a contact dermatitis due to high concentrations of foscarnet in urine. It usually resolves rapidly following discontinuation of the drug.
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