Valganciclovir hydrochloride dosage and administration

# dosage and administration

## General Dosing Information
- Valcyte for oral solution and tablets should be taken with food .
- Valcyte for oral solution (50 mg/mL) must be prepared by the pharmacist prior to dispensing to the patient .
- The bioavailability of ganciclovir from Valcyte is significantly higher than from ganciclovir capsules. Therefore, Valcyte tablets cannot be substituted for ganciclovir capsules on a one-to-one basis .
- Adult patients should use Valcyte tablets, not Valcyte for oral solution.

## Adult Patients With Normal Renal Function
For dosage recommendations in adult patients with renal impairment see Dosage and Administration (2.5).
Treatment of CMV Retinitis:
- Induction: The recommended dose is 900 mg (two 450 mg tablets) twice a day for 21 days.
- Maintenance: Following induction treatment, or in adult patients with inactive CMV retinitis, the recommended dose is 900 mg (two 450 mg tablets) once a day.
Prevention of CMV Disease:
- For adult patients who have received a heart or kidney-pancreas transplant, the recommended dose is 900 mg (two 450 mg tablets) once a day starting within 10 days of transplantation until 100 days post-transplantation.
- For adult patients who have received a kidney transplant, the recommended dose is 900 mg (two 450 mg tablets) once a day starting within 10 days of transplantation until 200 days post-transplantation.

## Pediatric Patients
Prevention of CMV Disease:For pediatric patients 4 months to 16 years of age who have received a kidney or heart transplant, the recommended once daily dose of Valcyte starting within 10 days of transplantation until 100 days post-transplantation is based on body surface area (BSA) and creatinine clearance (CrCl) derived from a modified Schwartz formula, and is calculated using the equation below:
- Pediatric Dose (mg) = 7  BSA  CrCl (calculated using a modified Schwartz formula). If the calculated Schwartz creatinine clearance exceeds 150 mL/min/1.73m2, then a maximum value of 150 mL/min/1.73m2 should be used in the equation.
where k =
0.45 for patients aged 4 months to < 1 year,
0.45 for patients aged 1 to < 2 years (note k value is 0.45 instead of the typical value of 0.55),
0.55 for boys aged 2 to < 13 years and girls aged 2 to 16 years, and
0.7 for boys aged 13 to 16 years.
All calculated doses should be rounded to the nearest 25 mg increment for the actual deliverable dose. If the calculated dose exceeds 900 mg, a maximum dose of 900 mg should be administered. Valcyte for oral solution is the preferred formulation since it provides the ability to administer a dose calculated according to the formula above; however, Valcyte tablets may be used if the calculated doses are within 10% of available tablet strength (450 mg). For example, if the calculated dose is between 405 mg and 495 mg, one 450 mg tablet may be taken.

## Preparation of Valcyte for Oral Solution
Prior to dispensing to the patient, Valcyte for oral solution must be prepared by the pharmacist as follows :
- Measure 91 mL of purified water in a graduated cylinder.
- Shake the Valcyte bottle to loosen the powder. Remove the child resistant bottle cap and add approximately half the total amount of water for constitution to the bottle and shake the closed bottle well for about 1 minute. Add the remainder of water and shake the closed bottle well for about 1 minute. This prepared solution contains 50 mg of valganciclovir free base per 1 mL.
- Remove the child resistant bottle cap and push the bottle adapter into the neck of the bottle.
- Close bottle with child resistant bottle cap tightly. This will assure the proper seating of the bottle adapter in the bottle and child resistant status of the cap.
- Store constituted oral solution under refrigeration at 2C to 8C (36F to 46F) for no longer than 49 days. Do not freeze.
- Write the date of expiration of the constituted oral solution on the bottle label.
The patient package insert, which includes the dosing instructions for patients, and 2 oral dispensers should be dispensed to the patient .

## Renal Impairment
Dosage recommendations for adult patients with reduced renal function are provided in Table 1. For adult patients on hemodialysis (CrCl <10 mL/min), a dose recommendation for Valcyte cannot be given .
Dosing in pediatric patients with renal impairment can be done using the recommended equations because CrCl is a component in the calculation .

## Handling and Disposal
Caution should be exercised in the handling of Valcyte tablets and Valcyte for oral solution. Tablets should not be broken or crushed. Because valganciclovir is considered a potential teratogen and carcinogen in humans, caution should be observed in handling broken tablets, the powder for oral solution, and the constituted oral solution . Avoid direct contact with broken or crushed tablets, the powder for oral solution, and the constituted oral solution with skin or mucous membranes. If such contact occurs, wash thoroughly with soap and water, and rinse eyes thoroughly with plain water.
Because ganciclovir shares some of the properties of antitumor agents (i.e., carcinogenicity and mutagenicity), consideration should be given to handling and disposal according to guidelines issued for antineoplastic drugs. Several guidelines on this subject have been published. However, there is no general agreement that all of the procedures recommended in the guidelines are necessary or appropriate .