Home Drug Guide Valganciclovir Hydrochloride

Drug Guide

Generic Name

Valganciclovir Hydrochloride

Brand Names Valcyte

Classification

Therapeutic: Antiviral, Antiviral Agent for CMV infections

Pharmacological: Ganciclovir prodrug, Nucleoside analog

FDA Approved Indications

Treatment of cytomegalovirus (CMV) retinitis in immunocompromised patients, such as those with AIDS
Prevention of CMV disease in solid organ transplant patients

Mechanism of Action

Valganciclovir is a prodrug of ganciclovir. After oral administration, it is rapidly converted to ganciclovir, which inhibits viral DNA polymerase by incorporation into viral DNA, leading to chain termination and inhibition of viral replication.

Dosage and Administration

Adult: Typically 900 mg twice daily for induction, then 900 mg once daily for maintenance, adjusted based on renal function.

Pediatric: Dosing based on body weight and renal function, typically 16 mg/kg BID for induction in pediatric patients.

Geriatric: Adjust dose based on renal function, careful monitoring needed.

Renal Impairment: Dose adjustments are necessary based on the degree of renal dysfunction.

Hepatic Impairment: No specific adjustments documented, but caution advised.

Pharmacokinetics

Absorption: Good oral bioavailability (~60%), bioavailability increases with food.

Distribution: Widely distributed in body tissues and fluids, crosses the blood-brain barrier.

Metabolism: Converted to ganciclovir; minimal hepatic metabolism.

Excretion: Primarily excreted unchanged in urine via glomerular filtration and tubular secretion.

Half Life: Approximately 4-6 hours in individuals with normal renal function.

Contraindications

Hypersensitivity to valganciclovir or ganciclovir.

Precautions

Use with caution in pregnant women, nursing mothers, and patients with renal impairment; monitor renal function closely. Risk of hematological toxicity.

Adverse Reactions - Common

Granulocytopenia (very common)
Thrombocytopenia (common)
Anemia (common)
Nausea (common)
Vomiting (common)

Adverse Reactions - Serious

Myelosuppression leading to neutropenia, anemia, thrombocytopenia (serious)
Neutropenic fever (serious)
Altered mental status or seizures (rare)
Severe hypersensitivity reactions (rare)

Drug-Drug Interactions

Mycophenolate mofetil (antagonistic effect on immune suppression),
Cytotoxic drugs,
Other nephrotoxic drugs.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function, complete blood counts (CBC), and for signs of infection or hematological toxicity.

Diagnoses:

Risk for infection due to immunosuppression
Risk for neutropenia or other hematological toxicity.

Implementation: Administer as prescribed, monitor labs regularly, educate patient on signs of toxicity.

Evaluation: Therapeutic efficacy observed through reduction in CMV viral load and prevention of CMV disease; toxicity managed through dose adjustments.

Patient/Family Teaching

Take medication exactly as prescribed.
Report any signs of infection, unusual bruising, bleeding, or allergic reactions.
Maintain good hygiene to prevent infections.
Stay well-hydrated to prevent renal toxicity.

Special Considerations

Black Box Warnings:

Myelosuppression leading to neutropenia, anemia, thrombocytopenia, which may be severe and require discontinuation.
Potential for carcinogenic and teratogenic effects. Use only if clearly indicated.
Use in pregnant women is contraindicated.

Genetic Factors: No specific genetic factors alter dosing currently known.

Lab Test Interference: Can cause hematological abnormalities that interfere with routine blood tests.

Overdose Management

Signs/Symptoms: Severe cytopenias, renal failure, or neurological symptoms.

Treatment: Supportive care, possible hemodialysis to enhance drug removal, monitor and treat symptoms as needed.

Storage and Handling

Storage: Store at room temperature (15-30°C), protect from moisture and light.

Stability: Stable for up to 24 months under proper conditions.