Dosing and uses of Vistide (cidofovir)
Adult dosage forms and strengths
injectable solution
- 75mg/mL
Cytomegalovirus Retinitis
Induction treatment: 5 mg/kg IV over 1 hour, once/week x2 weeks
Maintenance treatment: 5 mg/kg IV q2Weeks
Serum creatinine (SCr) increase 0.3-0.4 mg/dL above baseline: Reduce to 3 mg/kg IV
SCr increase >0.4 mg/dL above baseline: Discontinue therapy
Monitor: SCr, urine protein, WBC with differential prior to each dose, IOP, visual acuity
Concomitant Therapy
Must administer probenecid orally with each dose of cidofovir
Probenecid dose: Must administer 2 g of probenecid 3 hours prior to each cidofovir dose and 1 g at 2 hours and again at 8 hours after completion of 1 hour cidofovir infusion (for a total of 4 g); ingestion of food prior to each dose of probenecid may reduce drug-related nausea and vomiting
Hydration: Must receive at least 1 L of 0.9% (normal) saline solution IV prior to each infusion of cidofovir; should administer over 1-2 hours; may administer a second liter over 1-3 hours at start of cidofovir infusion or immediately following infusion if tolerated
Pediatric dosage forms and strengths
<18 years old: Safety & efficacy not established
Vistide (cidofovir) adverse (side) effects
>10%
Infection
Chills
Fever
Headache
Amnesia
Anxiety
Confusion
Seizures
Insomnia
Weakness
Paresthesia
Alopecia
Rash
Acne
Skin discoloration
Nausea
Vomiting
Diarrhea
Anorexia
Abdominal pain
Constipation
Dyspepsia
Gastritis
Thrombocytopenia
Neutropenia
Anemia
Amblyopia
Conjunctivitis
Ocular hypotony
Tubular damage
Proteinuria
Elevated creatinine
1-10%
Hypotension
Diaphoresis
Pallor
Syncope
Tachycardia
Dizziness
Hallucinations
Depression
Somnolence
Malaise
Pruritus
Urticaria
Hyperglycemia
Hyperlipidemia
Hypocalcemia
Hypokalemia
Dehydration
Abnormal taste
Stomatitis
Glycosuria
Hematuria
Urinary incontinence
Urinary tract infections
Skeletal pain
Retinal detachment
Iritis
Uveitis
Abnormal vision
Pneumonia
Rhinitis
Sinusitis
Allergic reactions
Warnings
Black box warnings
Renal impairment is the major toxicity, and acute renal failure resulting in dialysis or contributing to death have occurred with as few as 1 or 2 doses
Reduce nephrotoxicity risk by IV prehydration with normal saline, and administration of probenecid must be used with each infusion
Renal function (serum creatinine and urine protein) must be monitored within 48 hr prior to each dose, and, if necessary, modify dose in renal function as appropriate
Contraindicated if taking other nephrotoxic agents
Neutropenia observed; monitor neutrophil counts
Indicated only for the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS)
Animal studies showed cidofovir was carcinogenic, teratogenic, and caused hypospermia
Contraindications
Hypersensitivity to cidofovir or probenecid
SCr >1.5 mg/dL, CrCl <55 mL/min, urine protein >100 mg/dL (2+ proteinuria)
Direct intraocular injection
Concomitant nephrotoxic drugs
Cautions
Risk of nephrotoxicity (dose-limiting)
Risk of neutropenia
Probenecid must be administered w/each dose: 2 g PO 3 hr before cidofovir, 1 g at 2 hr & 8 hr after completion of cidofovir infusion
1 L saline IV with each cidofovir infusion; 1 add'l liter if pt can tolerate
Pregnancy and lactation
Pregnancy category: C
Lactation: It is not known whether cidofovir is excreted in milk. It should not be administered to nursing mothers. The CDC advises HIV-infected women not to breast-feed to avoid postnatal transmission of HIV.
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Vistide (cidofovir)
Distribution: Vd: 0.54 L/kg; does not cross significantly into CSF
Protein Bound: <6%
Half-life elimination: 2.6 hr
Metabolism: minimal; phosphorylation occurs intracellularly
Excretion: urine
Mechanism of action
Inhibits viral DNA synthesis in CMV
Administration
IV Preparation
Administer within 24 hr of dilution; refrigerate if not used immediately but still use within 24 hr
Admixtures should be allowed to equilibrate to room temp prior to use
IV Administration
For IV infusion only
Infuse in 100 mL NS over 1 hr
Prehydrate with 1 L of NS IV over 1-2 hr prior to cidofovir infusion; a second liter may be administered over a 1-3 hr period immediately following infusion, if tolerated
Storage
Store at controlled room temp
Store admixtures under refrigeration
