cidofovir

cidofovir /ci·dof·o·vir/ (sĭ-dof´o-vir) an antiviral nucleoside analogue used in the treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome.

---

cidofovir,

an antiviral.

indication It is used to treat cytomegalovirus retinitis in patients with AIDS.

contraindications Known hypersensitivity to acyclovir or this drug prohibits its use.

adverse effects Life-threatening effects include coma, hemorrhage, hematuria, granulocytopenia, thrombocytopenia, irreversible neutropenia, anemia, and eosinophilia. Other serious adverse effects include confusion, psychosis, tremors, somnolence, arrhythmias, hypertension/hypotension, retinal detachment in cytomegalovirus retinitis, abnormal liver function tests, increased creatinine, increased blood urea nitrogen, and phlebitis.

---

cidofovir [si-dof´ah-vir]

an antiviral nucleoside analogue used in treatment of cytomegalovirus retinitis in patients with acquired immunodeficiency syndrome; administered by intravenous infusion.

---

cidofovir Warning - Hazardous drug!

Vistide

Pharmacologic class: Purine nucleotide cytosine analog

Therapeutic class: Antiviral

Pregnancy risk category C

FDA Boxed Warning

• Drug is indicated only for treatment of cytomegalovirus (CMV) retinitis in patients with AIDS.
• Renal impairment is major toxicity. As few as one or two doses have caused acute renal failure resulting in dialysis or contributing to death. To reduce possible nephrotoxicity, prehydrate with I.V. normal saline solution and give probenecid with each drug infusion. Monitor renal function within 48 hours before each dose, and modify dosage as indicated.
• Drug is contraindicated in patients receiving other nephrotoxic agents.
• Drug may cause neutropenia. Monitor neutrophil counts during therapy.
• In animal studies, drug was carcinogenic and teratogenic and caused hypospermia.

Action

Exerts antiviral effect by interfering with DNA synthesis of CMV, thereby inhibiting viral replication

Availability

Solution for injection: 75 mg/ml in 5-ml, single-use vials

⊘Indications and dosages

➣ CMV retinitis in AIDS patients

Adults: 5 mg/kg I.V. infused over 1 hour q week for 2 continuous weeks; then 5 mg/kg I.V. once q 2 weeks as a maintenance dose

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug, probenecid, or other sulfa-containing agents
• Creatinine level above 1.5 mg/dl, calculated creatinine clearance of 55 ml/minute or less, or urine protein level of 100 mg/dl or higher
• Concurrent use of nephrotoxic drugs

Precautions

Use cautiously in:
• renal impairment
• elderly patients
• pregnant or breastfeeding patients
• children younger than age 12 (safety and efficacy not established).

Administration

☞ Be aware that drug carries a high risk of nephrotoxicity. Follow administration instructions carefully, including preinfusion and postinfusion hydration with I.V. normal saline solution.
• Premedicate with probenecid 2 g P.O., as prescribed, 3 hours before starting cidofovir infusion.
• Before starting infusion, give 1 L of normal saline solution over 1 to 2 hours.
• Mix I.V. dose in 100 ml of normal saline solution and infuse over 1 hour using infusion pump.
• Give 1 L of normal saline solution during or immediately after cidofovir infusion (unless contraindicated).
• Administer probenecid 1 g 2 hours and 8 hours after infusion ends, as prescribed.
☞ If drug touches skin, flush thoroughly with water.

Route	Onset	Peak	Duration
I.V.	Rapid	End of infusion	Unknown

Adverse reactions

CNS: headache, seizures, coma

EENT: decreased intraocular pressure

GI: nausea, vomiting, diarrhea, anorexia, oral candidiasis

GU: proteinuria, nephrotoxicity

Hematologic: neutropenia

Hepatic: hepatomegaly

Metabolic: metabolic acidosis

Musculoskeletal: muscle contractions

Respiratory: dyspnea, increased cough

Skin: rash, alopecia

Other: pain, fever, chills, infection, pain at I.V. site

Interactions

Drug-drug. Nephrotoxic drugs: increased risk of nephrotoxicity

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, blood urea nitrogen, creatinine, lactate dehydrogenase: increased values

Bicarbonate, creatinine clearance, hemoglobin, neutrophils, platelets: decreased values

Patient monitoring

• Assess white blood cell count and creatinine and urine protein levels within 48 hours of each dose.
• Closely monitor intraocular pressure and visual acuity.
• Monitor hepatic enzyme levels in patients with hepatic disease.

Patient teaching

☞ Tell patient to immediately report fever, vision changes, nausea, vomiting, rash, or urinary output changes.
• Instruct patient to take probenecid, as prescribed, before each dose and to have regular eye examinations.
• Urge female patient of childbearing age to use effective contraception during and for 1 month after therapy.
• Instruct male patients to use barrier contraception during and for 3 months after therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

---

cidofovir

Forvade, GS-504, HPMPC, Vistide AIDS A nucleotide analogue effective against a broad spectrum of herpesviruses Indications CMV retinitis, CMV-induced blindness, genital warts Adverse effect Nephrotoxicity