GANCICLOVIR

GANCICLOVIR
(gan-ci'clo-vir)
Cytovene
Classifications: antiviral agent;
Therapeutic: antiviral

Prototype: Acyclovir
Pregnancy Category: C

Availability

250 mg, 500 mg capsules; 500 mg powder for injection

Action

Ganciclovir is a synthetic purine nucleoside analog that is an antiviral drug active against cytomegalovirus (CMV). It inhibits the replication of CMV DNA.

Therapeutic Effect

Sensitive human viruses include CMV, herpes simplex virus-1 and -2 (HSV-1, HSV-2), Epstein-Barr virus, and varicella-zoster virus.

Uses

CMV retinitis, prophylaxis and treatment of systemic CMV infections in immunocompromised patients including HIV-positive and transplant patients.

Contraindications

Hypersensitivity to ganciclovir or acyclovir; infection; severe thrombocytopenia; pregnancy (category C), lactation.

Cautious Use

Renal impairment, older adults, bone marrow suppression; chemotherapy; radiation therapy.

Route & Dosage

Induction Therapy
Adult/Child (>3 mo): IV 5 mg/kg q12h for 14–21 d (doses may range from 2.5–5 mg/kg q8–12h for 10–35 d)

Maintenance Therapy
Adult/Child: IV 5 mg/kg qd 7 d/wk or 6 mg/kg qd 5 d/wk PO 1000 mg t.i.d. or 500 mg 6 times/d q3h while awake

Prevention of CMV Disease in Transplant Recipients
Adult/Child: IV 5 mg/kg q12h 7–14 d, then 5 mg/kg q.d. or 6 mg/kg/d 5 d/wk

Renal Impairment
Clcr 50–70 mL/min: use 50% of dose; 25–50 mL/min: use 50% of dose and q24h interval; 10–25 mL/min: use 25% of dose and q24h interval
Hemodialysis: Give dose post-dialysis

Administration

  • Note: Do not administer if neutrophil count falls below 500/mm3 or platelet count falls below 25,000/mm3.
  • Avoid direct contact of powder in capsules or solution with skin and mucous membranes. Wash thoroughly with soap and water if contact occurs.
Oral
  • Give with food.
Intravenous
  • IV administration to infants and children: Verify correct IV concentration and rate of infusion with physician.

PREPARE: Intermittent: ??Reconstitute the 500-mg vial using only 10 mL of sterile water (supplied) for injection immediately before use to yield 50 mg/mL.??Shake well to dissolve.??Withdraw the ordered amount and add to 100 mL of NS, D5W, or RL (volume less than 100 mL may be used, but the final concentration should be <10 mg/mL). 

ADMINISTER: Intermittent: Give at a constant rate over 1 h. Avoid rapid infusion or bolus injection.  

INCOMPATIBILITIES Solution/additive: Amino acid solutions (TPN), bacteriostatic water for injection, foscarnet. Y-site: Amifostine, amsacrine, aztreonam, cefepime, cytarabine, doxorubicin, fludarabine, foscarnet, gemcitabine, ondansetron, piperacillin/tazobactam, sargramostim, tacrolimus, TPN, vinorelbine.

  • Store reconstituted solutions refrigerated at 4° C; use within 12 h.
  • Store infusion solution refrigerated up to 24 h of preparation.

Adverse Effects (≥1%)

CNS: Fever, headache, disorientation, mental status changes, ataxia, coma, confusion, dizziness, paresthesia, nervousness, somnolence, tremor. CV: Edema, phlebitis. GI: Nausea, diarrhea, anorexia, elevated liver enzymes. Hematologic: Bone marrow suppression , thrombocytopenia, granulocytopenia, eosinophilia, leukopenia, hyperbilirubinemia. Metabolic: Hyperthermia, hypoglycemia. Urogenital: Infertility. Skin: Rash.

Interactions

Drug: antineoplastic agents, amphotericin B, didanosine, trimethoprim-sulfamethoxazole (TMP-SMZ), dapsone, pentamidine, probenecid, zidovudine may increase bone marrow suppression and other toxic effects of ganciclovir; may increase risk of nephrotoxicity from cyclosporine; may increase risk of seizures due to imipenem-cilastatin. Oral product increases didanosine levels.

Pharmacokinetics

Onset: 3–8 d. Duration: Clinical relapse can occur 14 d to 3.5 mo after stopping therapy; positive blood and urine cultures recur 12–60 d after therapy. Distribution: Distributes throughout body including CSF, eye, lungs, liver, and kidneys; crosses placenta in animals; not known if distributed into breast milk. Metabolism: Not metabolized. Elimination: Unchanged in urine. Half-Life: 2.5–4.2 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Neutrophil and platelet counts at least every other day during twice-daily dosing and weekly thereafter; more frequent monitoring may be indicated in certain patients. Monitor serum creatinine or creatinine clearance at least q2wk. Closely monitor renal function in the older adult.
  • Inspect IV insertion site throughout infusion for signs and symptoms of phlebitis.

Patient & Family Education

  • Note: Drug is not a cure for CMV retinitis; follow regular ophthalmologic examination schedule.
  • Drink lots of fluids during therapy.
  • Use barrier contraception throughout therapy and for at least 90 d afterwards.
  • Maintain frequent hematologic monitoring.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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