The U.S. Food and Drug administration announced on Wednesday that they have updated the dosage recommendation for youths that take Valcyte (valganciclovir), a drug used by patients receiving heart and kidney transplants.

The FDA said in a written statement to health care professionals, “The update is intended to prevent drug overdosing of children with low body weight, low body surface area, and very low serum creatinine.”

Valcyte is an antiviral drug used in patients ranging from four months to sixteen years old that have undergone heart or kidney transplants.  It is said to be effective in the prevention of cytomegalovirus, a disease known to cause severe illnesses in patients with weakened immune systems.

Valcyte has also been prescribed to AIDS patients when the disease effects the patients eyes and sometimes in pancreas transplant patients.

Health care professionals have been asked to report adverse effects of the updated recommendations to the FDA.