Foscarnet

Background

• Inhibits DNA polymerase in human herpesviruses
• Indications: CMV after hematopoietic stem cell transplantation, CMV after solid organ transplantation, Cytomegalovirus, Herpes simplex virus, Herpesviridae, Post-transplant acute limbic encephalitis

Spectrum of Activity

• Active against all human herpesviruses

Mechanism of Action

• Acts as a pyrophosphate analogue that competitively and reversibly inhibits herpesvirus DNA polymerase, causing premature chain termination of DNA

Pharmacokinetics and Pharmacodynamics

• CSF penetration 66% of serum levels

Dosing

Pediatric Dosing

• Induction: foscarnet 60 mg/kg IV q8h or 90 mg/kg IV q12h
• Maintenance: foscarnet 90 to 120 mg/kg IV q24h

Safety

Adverse Events

• Most common AEs include infusion-related nausea, electrolyte abnormalities, and acute kidney injury
  • Renal tubular nephrotoxicity is common, dose-dependent, and usually reversible if drug is stopped early
  • Crystal glomerular nephropathy also occurs
  • Electrolyte abnormalities, including hypocalcemia, hypophosphatemia, hyperphosphatemia, hypomagnesemia, and hypokalemia
  • Nausea is very common, and can be debilitating
    • Minimize with concurrent IV and oral hydration, antiemetics, and slowing the infusion rate1
• Other AEs include:
  • Seizure
  • Genital ulcers
  • Anemia
  • Nephrogenic diabetes insipidus

Monitoring

• Close monitoring of electrolytes and creatinine is required