gan·ci·clo·vir (g n-s  kl -vîr)n. An antiviral agent derived from guanine and used in the prevention and treatment of opportunistic cytomegalovirus infections. |
ganciclovir
ganciclovir (gansī´klōvir),
drug class: antiviral;
action: inhibits replication of most herpes viruses in vitro; in vivo by selective inhibition of human cytomegalovirus (CMV) DNA polymerase and by direct incorporation into viral DNA;
uses: CMV-retinitis in patients with AIDS.
ganciclovir (DHPG) Warning - Hazardous drug!
Cymevene (UK), Cytovene, Vitrasert
Pharmacologic class: Acyclic purine nucleoside analog of 2'-deoxyguanosine
Therapeutic class: Antiviral
Pregnancy risk category C
FDA Boxed Warning
• Drug may lead to granulocytopenia, anemia, and thrombocytopenia. In animal studies, it was carcinogenic and teratogenic and caused aspermatogenesis.
• Drug is indicated only to treat cytomegalovirus (CMV) retinitis in immunocompromised patients and to prevent CMV disease in at-risk transplant patients.
Action
Inhibits binding of deoxyguanosine triphosphate to DNA polymerase by terminating DNA synthesis, thereby inhibiting viral replication
Availability
Capsules: 250 mg, 500 mg
Injection: 500 mg/vial
Intravitreal implant: 4.5 mg
⊘Indications and dosages
➣ Prevention of CMV in advanced human immunodeficiency virus (HIV) infection
Adults: 1,000 mg P.O. t.i.d.
➣ Prevention of CMV in transplant recipients
Adults: 5 mg/kg I.V. q 12 hours for 7 to 14 days; then 5 mg/kg/day 7 days per week or 6 mg/kg/day 5 days per week
➣ CMV retinitis in immunocompromised patients
Adults and children ages 9 and older: Intravitreal implant (4.5 mg) placed during intraocular surgery
Adults and children older than 3 months: Initially, 5 mg/kg I.V. q 12 hours for 14 to 21 days, followed by a maintenance dosage of 5 mg/kg/day 7 days per week or 6 mg/kg 5 days per week. For P.O. maintenance, 1,000 mg P.O. t.i.d. or 500 mg P.O. q 3 hours while patient is awake.
Dosage adjustment
• Renal impairment
• Elderly patients
Off-label uses
• CMV gastroenteritis, CMV pneumonia
Contraindications
• Hypersensitivity to drug or acyclovir
• Neutropenia or thrombocytopenia
• Contraindications for intraocular surgery, such as external infections or thrombocytopenia (with intravitreal implant)
• Breastfeeding
Precautions
Use cautiously in:
• renal impairment
• history of cytopenic reactions
• pregnant patients
• children younger than age 9 (with intravitreal implant).
Administration
☞ Follow facility policy for handling and disposing of antineoplastic drugs. (Drug shares some properties with antitumor agents.)
☞ Don't let powder in capsules or I.V. solution contact skin, eyes, or mucous membranes. If contact occurs, wash skin thoroughly with soap and water, or flush eyes with water.
• Reconstitute 500-mg vial with 10 ml of sterile water; shake vial to dissolve drug. Then dilute drug again in 50 to 250 ml of compatible I.V. solution.
• If patient is on fluid restriction, dilute to a concentration of 10 mg/ml or less.
☞ Administer a single dose by I.V. infusion slowly (over at least 1 hour), using infusion pump or microdrip (60 gtt/ml).
• Give I.V. solution within 24 hours of dilution to reduce risk of bacterial contamination.
☞ Don't give by I.V. bolus or by I.M. or subcutaneous route.
• Administer oral doses with food.
• Be aware that intravitreal implant is designed to release drug over 5 to 8 months. Once drug is depleted (as shown by retinitis progression), implant may be removed and replaced.
☞ Handle intravitreal implant carefully by suture tab only, to avoid damage to polymer coating. (Damage could increase rate of drug release.)
| Route | Onset | Peak | Duration |
| P.O. | Slow | 2-4 hr | Unknown |
| I.V., intravit. | Unknown | Unknown | Unknown |
Adverse reactions
CNS: ataxia, confusion, dizziness, headache, drowsiness, tremor, abnormal thinking, agitation, amnesia, neuropathy, paresthesia, seizures, coma
CV: hypertension, hypotension, phlebitis, arrhythmias
EENT: vision loss for 2 to 4 weeks, vitreous loss, vitreous hemorrhage, cataract, retinal detachment, uveitis, endophthalmitis (all with intravitreal implant)
GI: nausea, vomiting, diarrhea, abdominal pain, dyspepsia, flatulence, anorexia, dry mouth
Hematologic: anemia, agranulocytosis, thrombocytopenia, leukopenia
Respiratory: pneumonia
Skin: rash, diaphoresis, pruritus
Other: fever; infection; chills; inflammation, pain, and phlebitis at injection site; sepsis
Interactions
Drug-drug. Amphotericin B, cyclosporine, other nephrotoxic drugs: increased risk of renal impairment and ganciclovir toxicity
Cilastatin, imipenem: increased seizure activity
Cytotoxic drugs: increased toxic effects
Immunosuppressants: increased immunologic and bone marrow depression
Probenecid: increased ganciclovir blood level
Zidovudine: increased risk of agranulocytosis
Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, creatinine, gamma-glutamyltransferase: increased values
Granulocytes, hemoglobin, neutrophils, platelets, white blood cells: decreased values
Liver function tests: abnormal results
Patient monitoring
• Monitor liver function test results.
• Monitor neutrophil and platelet counts.
• Assess fluid intake and output to ensure adequate hydration.
• Make sure patient has regular ophthalmic examinations during both induction and maintenance therapy.
☞ Monitor neurologic status closely; watch for seizures and coma.
☞ Check for signs and symptoms of infection, particularly sepsis.
Patient teaching
☞ Advise patient to immediately report signs and symptoms of infection, including those at infusion site.
☞Instruct patient to immediately report easy bruising or bleeding.
• Instruct patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Caution female patient not to breastfeed.
• Inform patient that drug may cause birth defects. Tell females to use effective birth control during therapy; advise males to use barrier contraception during and for 90 days after therapy.
☞ Caution patient not to open or crush capsule. If powder from capsule contacts skin or eyes, tell him to wash skin thoroughly with soap and water or flush eyes with water.
• Instruct patient to minimize GI upset by eating frequent, small servings of healthy food.
• Tell patient he'll undergo regular blood testing during therapy.
• Explain that drug doesn't cure CMV retinitis and that patient should have eye exams every 4 to 6 weeks during therapy.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.
ganciclovir
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