What Is Foscarnet?
Foscarnet, also known as phosphonomethanoic acid, is an antiviral compound with the formula CH3O5P. Its structure integrates formic acid with phosphoric acid, leading to its unique antiviral properties. Marketed primarily as Foscarnet sodium hydrate, it’s recognized under CAS numbers 4428-95-9 for the sodium salt and 34156-56-4 for the sodium hydrate.
Uses of Foscarnet
Foscarnet sodium hydrate is employed as an antiviral chemotherapeutic agent, particularly effective against cytomegalovirus (CMV) infections and human herpesvirus 6 encephalitis. It’s vital for treating CMV retinitis in AIDS patients, CMV infections in stem cell transplant recipients, and encephalitis post-transplantation. Marketed as Foscavir by Clinigen Corporation, it’s not recommended for congenital or neonatal CMV infections or as a preventive measure.
Properties of Foscarnet
Typically isolated as Foscarnet sodium hydrate, it appears as a white crystalline powder, with a molecular weight of 300.04 and formula CNa3O5P – 6H2O. Its solubility is limited to water, showing minimal solubility in ethanol and almost none in diethyl ether.
Types of Foscarnet
Foscarnet is available both as a pharmaceutical product for medical use and as a reagent for research. The drug version is provided in 250 mL vials for intravenous infusion at 24 mg/mL, while research-grade foscarnet is sold in various quantities from 25 mg to 100 g.
Other Information on Foscarnet
1. Mechanism of Action
Foscarnet acts by mimicking pyrophosphoric acid, selectively inhibiting viral DNA polymerase without affecting human DNA synthase. This mechanism blocks the replication of CMV and human herpesvirus 6.
2. Pharmaceutical Precautions
Prescribed under strict medical supervision, Foscarnet requires monitoring for potential decreases in serum calcium, magnesium, and potassium levels. Precautions include monitoring for hypersensitivity reactions, ensuring genital tract hygiene to prevent irritation and ulceration, and conducting thorough medical interviews to anticipate severe adverse reactions.