Valganciclovir

Strict adherence to dosage recommendations is essential to avoid overdose. Prolonged induction treatment may increase the risk of bone marrow toxicity. Patients whose retinitis worsens may repeat induction treatment, but the possibility of viral drug resistance should be considered; the duration of maintenance treatment should be determined on an individual basis. The SPC states that oral valganciclovir 900 mg twice daily is therapeutically equivalent to intravenous ganciclovir 5 mg/kg twice daily — that 5 mg/kg figure belongs to INTRAVENOUS GANCICLOVIR and is not a valganciclovir dose; do not use it to calculate valganciclovir. Valganciclovir is considered a potential teratogen and carcinogen in humans: avoid direct contact of broken or crushed tablets with skin or mucous membranes; if contact occurs wash thoroughly with soap and water and rinse eyes thoroughly with sterile water (or plain water if sterile water is unavailable). Elderly: safety and efficacy have not been established and no studies have been conducted in adults older than 65 years — since renal clearance decreases with age, give with special consideration of renal status. Hepatic impairment: safety and efficacy of the tablets have not been established. This draft REPLACES an earlier US-labelling-only draft; the UK SPC has now been used throughout (note the paediatric rounding increment differs — the UK SPC specifies rounding to the nearest 25 mg, not 10 mg).

Prevention of CMV disease in paediatric solid organ transplant patients, aged from birth, at risk of developing CMV disease. Once-daily dose (mg) = 7 x BSA x ClcrS, where BSA is body surface area (Mosteller formula) and ClcrS is creatinine clearance derived from the Schwartz formula. If the calculated Schwartz creatinine clearance exceeds 150 mL/min/1.73m2, use a maximum value of 150 mL/min/1.73m2 in the equation. Schwartz k values: 0.45 for patients aged under 2 years; 0.55 for boys aged 2 to under 13 years and girls aged 2 to 16 years; 0.7 for boys aged 13 to 16 years. These k values are based on the Jaffe method of measuring serum creatinine and may require correction when enzymatic methods are used; a lower k value may also be necessary in some sub-populations (for example paediatric patients with low birth weight). Refer to adult dosing for patients older than 16 years. Duration: paediatric kidney transplant — start within 10 days post-transplantation and continue until 200 days post-transplantation; other solid organ transplants — start within 10 days post-transplantation and continue until 100 days post-transplantation. Round all calculated doses to the nearest 25 mg increment for the actual deliverable dose. If the calculated dose exceeds 900 mg, administer a maximum dose of 900 mg. The oral solution is the preferred formulation because it allows a dose calculated by the formula to be given; film-coated tablets may be used only if the calculated dose is within 10% of an available tablet dose and the patient can swallow tablets (for example, a calculated dose between 405 mg and 495 mg may be given as one 450 mg tablet). Monitor serum creatinine regularly and adapt the dose for changes in height and weight during prophylaxis. Safety and efficacy in the TREATMENT of CMV retinitis have not been established in paediatric patients. Verify all paediatric dosing against a children's formulary.