Children are stratified by age group (3 through 11 years and 12 through 16 years). Samples for HIV-1 genotype and phenotype resistance testing are obtained at screening to aid in the selection of concomitant antiretrovirals. Simultaneous to initiating T-20, all patients begin a "new" optimized antiretroviral regimen based on the patients' prior treatment history, historical resistance testing results, and the results of the testing performed at screening. Patients are followed for safety and other assessments at Weeks 1, 2, and 4, then monthly through Week 24 and bimonthly through Week 48. Pharmacokinetic sampling at selected study visits are performed.
