On November 6, the Food and Drug Administration (FDA) approved revised dosing recommendations for zidovudine (Retrovir), a major anti-HIV drug used in children.

The update allows for treatment to begin at four weeks of age, as long as children weigh at least 4 kilograms (8 lb 13 oz). Previously the FDA had recommended starting children on zidovudine at six weeks of age.

Zidovudine, also known as azidothymidine (AZT), was the first drug approved for use against HIV in 1987. It is used for treating both adults and children with HIV infection and to prevent HIV transmission to children born to HIV-positive mothers.

Zidovudine can be administered as a tablet or capsule or as a syrup for children too young to swallow pills.

Initially, treatment recommendations for children included three daily doses of zidovudine. The amount was calculated based on the child’s body surface area.

In September 2008, the FDA approved a more convenient dosing regimen of twice a day for children six weeks to 18 years of age. It also included a way to provide drug amounts by the child’s weight in addition to body surface area.

For more information on the revised dosages for children, please visit the FDA Web site.