Foscarnet

Definition

Foscarnet is an antiviral medication primarily used to treat infections caused by certain DNA viruses, particularly those in the herpesvirus family. It works by inhibiting viral DNA polymerase, which is essential for viral replication, making it a critical option for patients who are resistant to other antiviral drugs or have renal impairment that limits the use of those medications.

5 Must Know Facts For Your Next Test

1. Foscarnet is particularly effective against cytomegalovirus (CMV) and is often used in patients with AIDS or organ transplant recipients.
2. It is administered intravenously, and dosage adjustments are necessary in patients with renal impairment due to its potential nephrotoxic effects.
3. Unlike acyclovir, foscarnet does not require phosphorylation to be active, allowing it to be effective against resistant strains of viruses.
4. Common side effects of foscarnet include renal toxicity, electrolyte imbalances, and hematological abnormalities, requiring careful monitoring during treatment.
5. Foscarnet's mechanism involves binding directly to the pyrophosphate-binding site of the viral DNA polymerase, inhibiting the enzyme's activity and thus blocking viral replication.

Review Questions

• How does foscarnet function as an antiviral medication and what makes it a viable option for patients with resistant viral infections?
  • Foscarnet functions by directly inhibiting viral DNA polymerase, which is essential for the replication of viral DNA. This mechanism makes it effective against viruses that have developed resistance to other antiviral agents like acyclovir. Since foscarnet does not require phosphorylation for activation, it can be used effectively in cases where the virus has mutated to evade other treatments, providing a critical alternative for managing serious viral infections.
• Discuss the implications of renal toxicity associated with foscarnet and how this affects its administration in patients with pre-existing conditions.
  • Renal toxicity is a significant concern when administering foscarnet, particularly in patients with pre-existing kidney conditions. The drug must be carefully dosed and monitored due to its nephrotoxic effects, requiring dose adjustments based on kidney function. In patients with compromised renal health, the risk of further deterioration increases, making it essential for healthcare providers to evaluate kidney function regularly and manage hydration and electrolyte levels during treatment.
• Evaluate the role of foscarnet in the management of herpesvirus infections in immunocompromised patients and the challenges faced in clinical settings.
  • Foscarnet plays a crucial role in managing herpesvirus infections, particularly CMV, in immunocompromised patients such as those with HIV/AIDS or organ transplant recipients. Its effectiveness against resistant strains presents a valuable treatment option when first-line therapies fail. However, challenges include monitoring for renal toxicity and potential side effects like electrolyte imbalances, which complicate its use. Additionally, the intravenous administration route limits its practicality compared to oral antivirals, necessitating careful patient selection and management strategies to optimize treatment outcomes.

Related terms

herpesviruses: A family of viruses that includes herpes simplex virus (HSV), varicella-zoster virus (VZV), and cytomegalovirus (CMV), known for their ability to establish latency in the host.

antiviral therapy:

A type of medication specifically designed to treat viral infections by targeting different stages of the viral lifecycle.

viral DNA polymerase: An enzyme crucial for the replication of viral DNA, which is a target for certain antiviral drugs like foscarnet.