Vistide
cidofovir
Pharmacologic class: Purine nucleotide cytosine analog
Therapeutic class: Antiviral
Pregnancy risk category C
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
See 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.
See If drug touches skin, flush thoroughly with water.
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
See 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
(sye-doe-foe-veer) cidofovir,Vistide
(trade name)Classification
Therapeutic: antiviralsIndications
Action
Therapeutic effects
Pharmacokinetics
Time/action profile
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| IV | rapid | end of infusion | unknown |
Contraindications/Precautions
Adverse Reactions/Side Effects
Central nervous system
- headache (most frequent)
- weakness (most frequent)
Ear, Eye, Nose, Throat
- ↓ intraocular pressure
- hearing loss
- iritis
- ocular hypotony
- uveitis
Respiratory
- dyspnea (most frequent)
- pneumonia
Gastrointestinal
- hepatotoxicity (life-threatening)
- pancreatitis (life-threatening)
- abdominal pain (most frequent)
- nausea (most frequent)
- vomiting (most frequent)
- anorexia
- diarrhea
Genitourinary
- renal failure (life-threatening)
- proteinuria (most frequent)
Dermatologic
- alopecia (most frequent)
- rash (most frequent)
Fluid and Electrolyte
- ↓ serum bicarbonate
Hematologic
- neutropenia (most frequent)
- anemia
Metabolic
- metabolic acidosis (life-threatening)
Miscellaneous
- chills (most frequent)
- fever (most frequent)
- infection (most frequent)
Interactions
Drug-Drug interaction
↑ 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
Renal Impairment
Intravenous (Adults) ↑ in serum creatinine of 0.3–0.4 mg/dL—↓ dose to 3 mg/kg; discontinue if serum creatinine ↑ ≥0.5 mg/dL over baseline.Availability (generic available)
Nursing implications
Nursing 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.
Intravenous Administration
- 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.
- Discuss with patient the possibility of hair loss. Explore coping strategies.
- Advise patients to have routine ophthalmologic exams after cidofovir therapy.
- 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.
Evaluation/Desired Outcomes
- Decrease in symptoms and arrest of progression of CMV retinitis in HIV-infected patients.