From the Guidelines
Foscarnet and cyclosporine should be used together with caution due to potential interactions that may increase the risk of nephrotoxicity. When these medications must be administered concurrently, close monitoring of renal function is essential, with baseline and regular assessment of serum creatinine, BUN, and electrolytes. According to the guidelines for the management of chronic kidney disease in HIV-infected patients 1, several drugs used in the treatment of HIV-infected persons, including foscarnet, may cause acute renal failure (ARF) and should be administered under close supervision.
Key considerations when using foscarnet and cyclosporine together include:
- Monitoring cyclosporine levels closely as foscarnet may affect its metabolism
- Maintaining adequate hydration during foscarnet therapy to minimize renal toxicity
- Regularly assessing serum creatinine, BUN, and electrolytes to detect early signs of renal impairment
- Being aware that patients with pre-existing renal impairment are at particularly high risk and may require more frequent monitoring or alternative treatment options if possible
The potential for nephrotoxicity with both medications is a significant concern, as foscarnet can cause direct tubular toxicity and cyclosporine can cause vasoconstriction of the afferent arteriole, creating an additive effect when used together 1. Therefore, it is crucial to carefully weigh the benefits and risks of concurrent use and to closely monitor patients for signs of renal impairment.
From the FDA Drug Label
Because of foscarnet's tendency to cause renal impairment, the use of FOSCAVIR should be avoided in combination with potentially nephrotoxic drugs such as aminoglycosides, amphotericin B, cyclosporine, acyclovir, methotrexate, tacrolimus and intravenous pentamidine (see above) unless the potential benefits outweigh the risks to the patient The interaction between Foscarnet and cyclosporine is that their concurrent use should be avoided due to the potential for renal impairment, as both drugs can be nephrotoxic. Caution is advised when considering concomitant administration of these drugs, and the potential benefits should be weighed against the risks to the patient 2.
From the Research
Foscarnet Interaction with Cyclosporine
- There is no direct evidence of an interaction between foscarnet and cyclosporine in the provided studies 3, 4, 5, 6, 7.
- However, both foscarnet and cyclosporine are known to be nephrotoxic, which may increase the risk of renal dysfunction when used together 5, 6, 7.
- Foscarnet is primarily eliminated unchanged through the kidneys, and its use requires aggressive dose adjustment during kidney failure 4.
- Cyclosporine-induced nephrotoxicity is a major limitation in transplant patients, and dose reduction may lead to substantial early improvement in renal function 6.
- The concomitant use of foscarnet and cyclosporine may increase the risk of acute renal failure, and renal function should be carefully monitored in patients receiving both drugs 7.