Valtrex (valacyclovir) Disease Interactions

There are 3 disease interactions with Valtrex (valacyclovir):

Valacyclovir (Includes Valtrex) ↔ Renal Impairment

Severe Potential Hazard, High plausibility

Applies to: Renal Dysfunction

Valacyclovir is almost completely converted in vivo to acyclovir, which is primarily eliminated by the kidney. Patients with renal impairment may be at greater risk for neuro- and nephrotoxicity (including further deterioration in renal function, tubular damage and acute renal failure) from acyclovir due to decreased drug clearance. Therapy with valacyclovir should be administered cautiously in patients with renal impairment. Dosage adjustments are recommended in patients with moderate to severe renal dysfunction.

References

  1. "Product Information. Valtrex (valacyclovir)." Glaxo Wellcome, Research Triangle Park, NC.
  2. Laskin OL, Longstreth JA, Whelton A, et al "Acyclovir kinetics in end-stage renal disease." Clin Pharmacol Ther 31 (1982): 594-600
  3. Laskin OL, Longstreth JA, Whelton A, et al "Effect of renal failure on the pharmacokinetics of acyclovir." Am J Med 73 (1982): 197-201

Valacyclovir (Includes Valtrex) ↔ Ttp/Hus

Severe Potential Hazard, Low plausibility

Applies to: Organ Transplant, Immunodeficiency, Bone Marrow Transplantation, Neutropenia

Cases of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) have been reported in patients with advanced HIV disease and in allogeneic bone marrow transplant and renal transplant recipients given valacyclovir 8 g/day during clinical trials. Although a causal relationship has not been established, therapy with valacyclovir should be administered cautiously in immunocompromised patients.

References

  1. "Product Information. Valtrex (valacyclovir)." Glaxo Wellcome, Research Triangle Park, NC.

Valacyclovir (Includes Valtrex) ↔ Hemodialysis

Moderate Potential Hazard, High plausibility

Applies to: hemodialysis

Valacyclovir is almost completely converted in vivo to acyclovir, which is substantially removed by hemodialysis. Plasma levels of acyclovir have been shown to reduce by 60% following 6 hours of dialysis. Valacyclovir should be administered after hemodialysis. Otherwise, an additional dose may be given after each hemodialysis session.

References

  1. Laskin OL, Longstreth JA, Whelton A, et al "Acyclovir kinetics in end-stage renal disease." Clin Pharmacol Ther 31 (1982): 594-600
  2. Krasny HC, Liao SH, de Miranda P, Laskin OL, Whelton A, Lietman PS "Influence of hemodialysis on acyclovir pharmacokinetics in patients with chronic renal failure." Am J Med 73 (1982): 202-4
  3. "Product Information. Valtrex (valacyclovir)." Glaxo Wellcome, Research Triangle Park, NC.

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Valtrex (valacyclovir) drug Interactions

There are 50 drug interactions with Valtrex (valacyclovir)

Drug Interaction Classification

The classifications below are a general guideline only. It is difficult to determine the relevance of a particular drug interaction to any individual given the large number of variables.

Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.

Do not stop taking any medications without consulting your healthcare provider.

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