valganciclovir hydrochloride

valganciclovir hydrochloride Warning - Hazardous drug!

Valcyte

Pharmacologic class: Synthetic guanine derivative

Therapeutic class: Antiviral

Pregnancy risk category C

FDA Boxed Warning

• Clinical toxicities of drug (which is metabolized to ganciclovir) include granulocytopenia, anemia, and thrombocytopenia. In animal studies, ganciclovir caused cancer, birth defects, and aspermatogenesis.

Action

Converts to its active form, inhibiting activity of cytomegalovirus (CMV)

Availability

Tablets: 450 mg

⊘Indications and dosages

➣ Active CMV retinitis in AIDS patients

Adults: For induction therapy, 900 mg P.O. b.i.d. for 21 days. For maintenance, 900 mg P.O. daily.

➣ CMV prevention in high-risk kidney, heart, and kidney-pancreas transplant patients

Adults: 900 mg P.O. daily with food, starting within 10 days of transplantation and continuing until 100 days after transplantation

Dosage adjustment

• Renal impairment

Contraindications

• Hypersensitivity to drug, its components, or ganciclovir
• Absolute neutrophil count below 500 cells/mm³, platelet count below 25,000 cells/mm³, or hemoglobin below 8 g/dl

Precautions

Use cautiously in:
• cytopenia, impaired renal function
• patients receiving myelosuppressive drug therapy or radiation therapy
• elderly patients
• pregnant or breastfeeding patients.

Administration

• Avoid direct contact with broken or crushed tablet. If skin contact occurs, wash thoroughly with soap and water; if eye contact occurs, rinse eyes thoroughly with plain water.

Route	Onset	Peak	Duration
P.O.	Unknown	1-3 hr	Unknown

Adverse reactions

CNS: headache, insomnia, sedation, dizziness, peripheral neuropathy, paresthesia, hallucinations, confusion, agitation, psychosis, ataxia, seizures

EENT: retinal detachment

GI: nausea, vomiting, diarrhea, abdominal pain

Hematologic: anemia, bone marrow depression, aplastic anemia, pancytopenia, thrombocytopenia, neutropenia

Other: fever, catheter-related infection, local or systemic infection, hypersensitivity reaction, sepsis

Interactions

Drug-drug. Cytotoxic drugs (such as adriamycin, amphotericin B, co-trimoxazole, dapsone, doxorubicin, flucytosine, pentamidine, vinblastine, vincristine): additive toxicity

Cilastatin, imipenem: seizures

Didanosine: decreased valganciclovir blood level, increased didanosine blood level

Nephrotoxic drugs (such as amphotericin B, cyclosporine): increased creatinine level

Probenecid: decreased renal clearance of valganciclovir

Zidovudine: increased risk of granulocytopenia and anemia

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, creatinine: increased levels

Creatinine clearance: decreased value

Granulocytes, hemoglobin, neutrophils, platelets, white blood cells: decreased levels

Drug-food. Any food: increased drug absorption

Patient monitoring

• Monitor CBC with white cell differential and platelet count. Watch for signs and symptoms of blood dyscrasias.
☞ Stay alert for hypersensitivity reaction and signs and symptoms of infection.
• Closely monitor neurologic status. Observe for signs and symptoms of impending seizure.
• Periodically assess creatinine level and creatinine clearance.

Patient teaching

• Instruct patient to take with food.
• Explain drug therapy to patient. Stress importance of taking drug exactly as prescribed to prevent overdose.
☞ Tell patient drug can cause serious adverse reactions. Teach him which ones to report immediately.
• Advise patient to avoid driving and other hazardous activities.
• Caution female of childbearing age to avoid pregnancy and breastfeeding.
• Urge male patient to use barrier contraception during and for 90 days after therapy.
• Instruct patient to have follow-up eye exams every 4 to 6 weeks, as well as periodic laboratory tests.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.