.

VALGANCICLOVIR HYDROCHLORIDE

Medical Diagnosis and Drugs, Medications
VALGANCICLOVIR HYDROCHLORIDE
(val-gan-ci'clo-vir)
Valcyte
Classifications: antiviral agent;
Therapeutic: antiviral
Prototype: Acyclovir
Pregnancy Category: C

Availability

450 mg tablets

Action

Rapidly converted to ganciclovir by intestinal and hepatic enzymes. In cells infected with cytomegalovirus (CMV), ganciclovir is phosphorylated to ganciclovir triphosphate, which inhibits viral DNA synthesis.

Therapeutic Effect

Antiviral drug active against cytomegalovirus (CMV). Prevents replication of viral CMV DNA.

Uses

Treatment of CMV retinitis; prevention of CMV disease in high-risk kidney, kidney-pancreas, and heart transplant patients (not effective in liver transplants).

Contraindications

Hypersensitivity to valganciclovir, ganciclovir, or acyclovir. Not recommended for persons on hemodialysis; renal failure; dental work; antimicrobial resistance; neutropenia, thrombocytopenia; pregnancy (category C), females of childbearing age; lactation.

Cautious Use

Impaired kidney function; older adults; dental disease; anemia; leukopenia; bone marrow depression; concomitant use of myelosuppressive drugs; irradiation. Safety and efficacy in children are not established.

Route & Dosage

Cytomegalovirus Prophylaxis
Adult: PO 900 mg once daily with food, starting within 10 d of transplantation until 100 d posttransplantation

Cytomegalovirus Retinitis Induction
Adult: PO 900 mg b.i.d. with food x 21 d

Cytomegalovirus Retinitis Maintenance
Adult: PO 900 mg q.d. with food

Renal Impairment
Clcr 40–59 mL/min: 450 mg b.i.d. (induction) or q.d. (maintenance); 25–39 mL/min: 450 mg q.d. (induction) or q2d (maintenance); 10–24 mL/min: 450 mg q2d (induction) or twice weekly (maintenance)

Administration

Oral
  • Exercise caution in handling tablets. Do not crush or break tablets. Avoid direct contact of crushed or broken tablets with skin or mucous membranes.
  • Give with food.
  • Do not give to patients on hemodialysis.
  • Store at 25°–30° C (77°–86° F).

Adverse Effects (≥1%)

Body as a Whole: Fever, local and systemic infections, hypersensitivity reactions. CNS: Headache, insomnia, peripheral neuropathy, paresthesia, convulsions, psychosis, confusion, hallucinations, agitation. GI: Diarrhea, nausea, vomiting, abdominal pain. Hematologic: Neutropenia, anemia, thrombocytopenia, pancytopenia, bone marrow suppression, aplastic anemia. Special Senses: Retinal detachment.

Interactions

Drug: antineoplastic agents, amphotericin B, didanosine, trimethoprim-sulfa-methoxazole (TMP-SMZ), dapsone, pentamidine, probenecid, zidovudine may increase bone marrow suppression and other toxic effects of valganciclovir; may increase risk of nephrotoxicity from cyclosporine; antiretroviral agents may decrease valganciclovir levels; valganciclovir may increase levels and toxicity of antiretroviral agents; may increase risk of seizures due to imipenem-cilastatin.

Pharmacokinetics

Absorption: Well absorbed from GI tract, 60% reaches systemic circulation as ganciclovir. Onset: 3–8 d. Peak: 1–3 h. 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: Metabolized in intestinal wall to ganciclovir, ganciclovir is not metabolized. Elimination: 94–99% of dose is excreted unchanged in urine. Half-Life: 4 h.

Nursing Implications

Assessment & Drug Effects

  • Withhold drug and notify physician for any of the following: Absolute neutrophil count <500 cells/mm3, platelet count <25,000/mm3, hemoglobin <8 g/dL, declining creatinine clearance.
  • Monitor for S&S of bronchospasm in asthma patients; notify physician immediately.
  • Lab tests: Baseline and frequent serum creatinine or creatinine clearance, CBC with differential, platelet count, Hct & Hgb.

Patient & Family Education

  • Schedule ophthalmologic follow-up examinations at least every 4–6 wk while being treated with valganciclovir.
  • Keep all scheduled appointments for laboratory tests.
  • Do not drive or engage in potentially hazardous activities until response to drug is known.
  • Report any of the following immediately: unexpected bleeding, infection.
  • Use effective methods of contraception (barrier and other types) during and for at least 90 d following treatment.
  • Discontinue drug and notify physician immediately in the event of pregnancy.

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

(11)