A PK and Salvage Study for Children With HIV-infection

Inclusion Criteria: 1. Confirmed HIV-1 infection by HIV-DNA PCR if \< 18 months old or by HIV ELISA if greater than or equal to 18 months old 2. Subject is less than or equal to 16 years of age at the day of the first dosing. 3. Subject is failing a current NRTI and/or NNRTI containing regimen and is naïve to protease inhibitor containing therapy. 4. Results of biochemistry and haematology testing should be within pre-specified ranges. 5. Subject is able to swallow capsules 6. Caretaker(s) is/are able and willing to sign the Informed Consent Form prior to screening evaluations. Exclusion Criteria: 1. History of sensitivity/idiosyncrasy to lopinavir, ritonavir, saquinavir or chemically related compounds or excipients which may be employed in the trial. 2. Relevant history or current condition that might interfere with drug absorption, distribution, metabolism or excretion. 3. Inability of both child and caregiver(s) to understand the nature and extent of the trial and the procedures required. 4. Use of any of concomitant medication, including the drug listed below, that may interfere with the pharmacokinetics of LPV/r or SQV. * NNRTIs * Rifampicin * Rifabutin * Phenobarbital * Phenytoine * Carbamazepine * Dexamethasone * Ketoconazole * Clarithromycin 5. Pregnancy