FDA approves new paediatric AZT dosing

On 19 September 2008, the FDA approved a paediatric efficacy supplement for AZT syrup, capsules and tablets allowing for a twice-daily dosing regimen in children 6 weeks to 18 years of age. It also provides for dosing by weight in addition to dosing by body surface area.

Previously, AZT dosing recommendations for the treatment of HIV in children included three times daily dosing with dose calculated using body surface area. The new label has recommendations for twice daily or three times daily dosing by weight or by body surface area. The new recommendations should allow for more convenient dosing (twice daily) of AZT (zidovudine, Retrovir) in children. The main changes include revisions to the Dosage and Administration section to include twice daily dosing in children as follows.

Paediatric patients (6 weeks to <18 years of age): Healthcare professionals should pay special attention to accurate calculation of the dose of AZT, transcription of the medication order, dispensing information, and dosing instructions to minimize risk for medication dosing errors.

Prescribers should calculate the appropriate dose of AZT for each child based on body weight (kg) and should not exceed the recommended adult dose.

Before prescribing AZT capsules or tablets, children should be assessed for the ability to swallow capsules or tablets. If a child is unable to reliably swallow an AZT capsule or tablet, the AZT Syrup should be prescribed.

The recommended dosage in pediatric patients 6 weeks of age and older and weighing >4 kg is provided in a dosing table (see FDA list serve sit or new prescribing information). AZT Syrup should be used to provide accurate dosage when whole tablets or capsules are not appropriate.

Alternatively, dosing for AZT can be based on body surface area (BSA) for each child. The recommended oral dose of RETROVIR is 480 mg/m2/day in divided doses (240 mg/m2 twice daily or 160 mg/m2 three times daily). In some cases the dose calculated by mg/kg will not be the same as that calculated by BSA.