cidofovir

General

Pronunciation
sye-doe-FOE-veer [Pronunciation]

Trade Name(s)

• Vistide

Pregnancy Category
Category C

Ther. class.
antivirals

Indications

Management of cytomegalovirus (CMV) retinitis in HIV-infected patients (with probenecid).

Action

Suppresses replication of CMV by inhibiting viral DNA synthesis.

Therapeutic Effect(s):
Slows progression of CMV retinitis; may not be curative.

Pharmacokinetics

Absorption: IV administration results in complete bioavailability.

Distribution: Unknown.

Metabolism and Excretion: Excreted mostly unchanged by the kidneys.

Half-life: Unknown.

TIME/ACTION PROFILE

ROUTE	ONSET	PEAK	DURATION
IV	rapid	end of infusion	unknown

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity to cidofovir, probenecid, or sulfonamides;

• Serum Cr >1.5 mg/dL, CCr ≤55 mL/min, or urine protein ≥100 mg/dL (≥2+ proteinuria);

• Concurrent use of foscarnet, amphotericin B, aminoglycoside anti-infectives, NSAIDs, or IV pentamidine.

Use Cautiously in:
Pregnancy or children (safety not established); breastfeeding is not recommended in HIV-positive patients.

Exercise Extreme Caution in:
Any condition or medication that increases the risk of dehydration.

Adverse Reactions/Side Effects

CNS: headache, weakness.

EENT: decreased intraocular pressure, hearing loss, iritis, ocular hypotony, uveitis.

Resp: dyspnea, pneumonia.

GI: HEPATIC DYSFUNCTION, PANCREATITIS, abdominal pain, nausea, vomiting, anorexia, diarrhea.

GU: RENAL FAILURE, proteinuria.

Derm: alopecia, rash.

F and E: decreased serum bicarbonate.

Hemat: neutropenia, anemia.

Metabolic: METABOLIC ACIDOSIS.

Misc: chills, fever, infection.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• ↑ risk of nephrotoxicity with aminoglycosides , amphotericin B , foscarnet , and pentamidine and should be avoided; wait 7 days after giving other nephrotoxic agents.

• Probenecid , which is required concurrently, may interact with acetaminophen , acyclovir , ACE inhibitors , barbiturates , benzodiazepines , bumetanide , methotrexate , famotidine , furosemide , NSAIDs , theophylline , and zidovudine .

Route/Dosage

• IV (Adults): 5 mg/kg once weekly for 2 wk, followed by 5 mg/kg every 2 wk (must be given with probenecid)..

Renal Impairment

• IV (Adults): Increase in serum creatinine of 0.3–0.4 mg/dL—decrease dose to 3 mg/kg; discontinue if serum creatinine increases ≥0.5 mg/dL over baseline..

Availability

• Solution for injection: 75 mg/mL in 5-mL ampules

Assessment

• Monitor vision for progression of CMV retinitis. Monitor ocular symptoms, intraocular pressure, and visual acuity periodically.

• Antiemetics and administration after a meal may minimize nausea and vomiting associated with probenecid. If allergic reactions occur in association with probenecid, pretreatment with antihistamines or acetaminophen should be considered.

• Monitor vital signs periodically. May cause fever, hypotension, and tachycardia. Monitor patients for early signs and symptoms of infection.

Lab Test Considerations

• Renal function, measured by serum Cr and urine protein, must be monitored within 48 hr before each dose and throughout cidofovir therapy. In patients with proteinuria, administer IV hydration and repeat urine protein test. If renal function deteriorates, dose modification or temporary discontinuation should be considered.

» Monitor WBC before each dose. Granulocytopenia may occur.

» May cause hyperglycemia, hyperlipemia, hypocalcemia, hypokalemia, and elevated alkaline phosphatase, AST, and ALT.

Potential Nursing Diagnoses

• Risk for infection (Indications)

Implementation

Probenecid and saline prehydration must be given with cidofovir to minimize renal toxicity. Probenecid must be administered 2 g orally given 3 hr before, then 1 g given 2 hr and 8 hr after completion of cidofovir infusion. Saline prehydration with 1 L of 0.9% NaCl must be given over 1–2 hr before cidofovir. A second liter over 1–3 hr is recommended concurrently with or after cidofovir.

» Patients receiving foscarnet, amphotericin B, aminoglycoside, NSAIDs, or IV pentamidine should wait at least 7 days after these agents to begin cidofovir.

IV Adminstration:

• pH:
6.7–7.6.

• Intermittent Infusion:

Diluent: Dilute in 100 mL of 0.9% NaCl. Solution is stable for 24 hr if refrigerated. Allow refrigerated solution to return to room temperature before administration.

• Rate:
Administer over 1 hr.

• Additive Incompatibility:
Information unavailable. Do not admix with other solutions or medications.

Patient/Family Teaching

• Inform patient that cidofovir is not a cure for CMV retinitis and that retinitis may continue to progress during and after therapy.

• Inform patient that concurrent antiretroviral therapy may be continued. However, zidovudine therapy should be temporarily discontinued or decreased by 50% on the days of cidofovir therapy because of the effects of probenicid on zidovudine.

• Advise patient of the possibility of renal toxicity from cidofovir. Emphasize the importance of routine lab tests to monitor renal function.

• Inform patient that cidofovir may have teratogenic effects. Women should use contraception during and for 1 mo after therapy. Men should use barrier contraception during and for 3 mo after therapy.

• Discuss with patient the possibility of hair loss. Explore coping strategies.

• Advise patients to have routine ophthalmologic exams after cidofovir therapy.

Evaluation/Desired Outcomes

Decrease in symptoms and arrest of progression of CMV retinitis in HIV-infected patients.