Safety and Efficacy of Switching From Stavudine or Zidovudine to Tenofovir DF in HIV-1 Infected Children

Tenofovir DF (oral powder or tablet): 300-mg tablets for participants \> 37 kg; 8-mg/kg oral powder (up to 300 mg) for participants ≤ 37 kg. During the extension phase, participants whose weight increases to \> 37 kg may be switched from the oral powder to the tenofovir DF tablet.

Zidovudine as prescribed by the investigator prior to study entry (pediatric participants \< 30 kg: 1 mg/kg/dose given every 12 hours; pediatric participants ≥ 30 kg: 30 mg twice daily).

Stavudine as prescribed by the investigator prior to study entry (pediatric participants 6 weeks to 12 years of age: 160 mg/m\^2 every 8 hours; pediatric participants \> 12 years of age: 300 mg twice daily).