• To evaluate the pharmacokinetics profile on day 14 of two different doses of TMC114 in combination with ritonavir in the pediatric population at steady-state and to provide dose recommendation of TMC114 per body weight in pediatric patients. [ Time Frame: 24 weeks ] [ Designated as safety issue: Yes ]
  

• To evaluate long-term safety, tolerability and efficacy of TMC114 in combination with low dose ritonavir administered twice daily. and other ARV agents over a 48-week treatment period at the recommended pediatric and adult doses. [ Time Frame: 48 weeks ] [ Designated as safety issue: No ]
  

This study is a randomized (patients are assigned different treatments based on chance), open-label Phase II trial to evaluate pharmacokinetics, safety, tolerability and efficacy in HIV-1 infected treatment experienced pediatric patients to support dose recommendations of TMC114 administered in combination with low-dose ritonavir and other ARV agents in the pediatric population aged from 6-17 years. Approximately 80 patients will be included in the trial. Patients will be considered treatment-experienced if they have received antiretroviral therapy (ART), including both commercially available as well as investigational ARVs indicated for the treatment of HIV-infection. The trial will be structured in two parts: Part I (pediatric dose selection): All assessments to be performed in Part I are targeted to provide dose recommendations of TMC114/rtv per body weight in patients > or equal to 20 kg up to < 50 kg. Maximally 48 treatment experienced HIV-1 infected pediatric patients will be randomized in a 1:1 ratio to receive either the adult equivalent dose of TMC114 with low-dose ritonavir twice daily. (Dose Group A) or a 20 to 33% higher dose of TMC114 with low-dose ritonavir twice daily (Dose Group B).The weight bands are as follows: from 20 - < 30 kg, from 30 - < 40 kg, and from 40 < 50 kg.To ensure an equal distribution across all weight bands, a minimum of 12 and a maximum of 18 patients per weight band will be recruited. Once Week 2 (Day 14) assessments are available for all Part I patients, a recommended pediatric dose of TMC114/rtv will be selected and communicated to the sites. Part I patients who are not on this dose will be switched to the recommended pediatric dose, and will continue the overall schedule of assessments up to Week 48 as Part II patients. Part II (recommended pediatric or adult dose): The assessments included in Part II are targeted to evaluate long-term safety, tolerability and efficacy on the recommended pediatric and adult dose, depending on body weight. The primary analysis will be done when all patients have been treated for 24 weeks or discontinued earlier. An updated and final analysis will be performed once all patients have been treated for 48 weeks, or have dropped out earlier (early withdrawal).

All patients of > = to 20 kg to < 50 kg in Part I will be on one of the two dose groups (A and B) of TMC114/rtv stratified by body weight within each weight band. Part I patients will switch to the recommended pediatric dose after dose selection (completion of Day 14) and will continue treatment in Part II up to 48 weeks. Part II patients weighing above or equal to 50 kg will receive the recommended adult dose of 600 mg TMC114/100 mg ritonavir orally twice daily for 48 weeks.