Cidofovir
Common Brand Names: Vistide
Therapeutic Class: Antiviral agent
Common Injectable Dosage Forms:
Solution for Injection: 75 mg/mL in 5 mL vials (preservative free)
Dosage Ranges:
Induction: 5 mg/kg IV over 1 hour once weekly for 2 consecutive weeks.
Maintenance: 5 mg/kg IV over 1 hour every other week.
Give 2 g probenecid orally 3 hours prior to each infusion and 1 g probenecid at 2 hours and 8 hours post-infusion (4 g total).
If SCr increases by more than 0.3-0.4 mg/dL, decrease cidofovir dose to 3 mg/kg; discontinue if SCr increases by 0.5 mg/dL or more or if ≥3+ proteinuria.
Use with caution in existing renal impairment.
Administration and Stability: Given by IV infusion over 1 hour. Hydrate patient with one liter NaCl 0.9% IV prior to cidofovir infusion. A second liter may be given over 1-3 hours after infusion, if tolerated. Dilute one vial in 100 mL normal saline. The must be prepared in Class II laminar hood with protective gear. pH 7.4
Pharmacology/Pharmacokinetics: Cidofovir suppresses CMV replication by selective inhibition of viral DNA synthesis. Incorporation of cidofovir into growing viral DNA chain results in decreased rate of viral DNA synthesis. Elimination half-life is approximately 2.6 hours. Excretion is primarily via urine. Less than 6% is bound to serum proteins. Cidofovir does not cross significantly into CSF.
Drug and Lab Interactions: Nephrotoxic drugs (e.g., amphotericin B, aminoglycosides) should not be used within 7 days of cidofovir. Temporarily discontinue or decrease zidovudine dose by 50% on day of cidofovir administration only.
Contraindications/Precautions: Contraindicated in patients hypersensitive to cidofovir, probenecid, or other sulfa medications. Use with caution in patients with SCr >1.5 mg/dL, CrCl <55 mg/min, or urine protein ≥100 mg/dL (≥2+ proteinuria). Use caution when using with or within 7 days of other nephrotoxic agents. Not for intraocular injections. Neutropenia has been reported in patients on cidofovir therapy. Indicated only for CMV retinitis treatment of HIV patients. Pregnancy Category C.
Monitoring Parameters: Cr, BUN, UAs within 48 hours of each dose, LFTs, WBCs, intraocular pressure, s/s of uveitis/iritis.
Adverse Effects: May cause chills, fever, headache, alopecia, rash, nausea, vomiting, diarrhea, anemia, neutropenia, increased intraocular pressure, increased creatinine and proteinuria.
Common Clinical Applications: Cidofovir is used in the treatment of cytomegalovirus (CMV) retinitis in patients with AIDS.
