Renal Impairment Considerations:

• Foscarnet is nephrotoxic; it can cause significant renal impairment. Prior to initiation and frequently during treatment, assess renal function. Calculating creatinine clearance before each dose can help adjust dosing appropriately.

• Encourage adequate hydration in patients to reduce the risk of nephrotoxicity.

Electrolyte Monitoring:

• Foscarnet can induce electrolyte imbalances, including hypocalcemia, hypomagnesemia, hypokalemia, and hypophosphatemia. Regular monitoring of serum electrolytes is crucial; adjust supplementation as needed.

• Watch for signs of electrolyte imbalance, such as muscle cramps, seizures, and cardiac rhythm disturbances.

Infusion-Related Considerations:

• Administer foscarnet via slow intravenous infusion over at least 2 hours to minimize renal toxicity and decrease the risk of infusion-related reactions, such as fever, chills, and nausea.

• Avoid rapid infusion, which is associated with increased risks of renal toxicity and electrolyte disturbances.

Management of Genital Ulcers:

• Foscarnet can cause genital ulcers, particularly in males. These are typically painful and may increase the risk of superinfection. Institute appropriate local or systemic treatment for these ulcers and consider sexual abstinence to prevent ulcer exacerbation and transmission.

Interaction with Other Medications:

• Foscarnet is known to interact with other nephrotoxic drugs, such as certain antibiotics and chemotherapeutic agents. Evaluate all concurrent medications and adjust or monitor treatment as necessary.

• Since foscarnet does not undergo significant metabolism by the liver and does not inhibit or induce hepatic enzymes, it has fewer drug-drug interactions compared to other antivirals.

Use in Special Populations:

• Exercise caution and adjust dosing in elderly patients due to the increased risk of renal impairment.

• The safety and efficacy of foscarnet in pediatric populations have not been fully established. Use only when clearly needed and under strict medical supervision.

Therapeutic Drug Monitoring:

• Although routine monitoring of foscarnet levels is not generally required, it can be beneficial in patients with fluctuating renal function or those who have a poor clinical response.

Intravenous Access Care:

• Ensure good intravenous access to prevent extravasation, which can cause severe local tissue damage. Assess the integrity of IV sites regularly during therapy.