Dual Boosted - Protease Inhibitor (PI) Pharmacokinetics (PK) Trial (Tipranavir / Ritonavir) in Highly Treatment-experienced HIV-1 Infected Patients

Inclusion criteria: * Signed informed consent prior to trial participation. * Human Immunodeficiency Virus type 1 (HIV-1) infected males or females ≥18 years of age. * Acceptable laboratory screening values in Trial 1182.12 (RESIST 1) or 1182.48 (RESIST 2), excluding genotype. * Genotypic resistance report from screening visit of study RESIST 1 or RESIST 2 indicating at least three mutations at protease codons 33, 82, 84, and 90. * At least 3 consecutive months experience taking ARVs from each of the classes of Nucleoside reverse transcriptase inhibitors (NRTI), Non-nucleoside reverse transcriptase inhibitor 1 (NNRTI), and Protease Inhibitor (PI) at some point in treatment history, with at least 2 PI-based regimens, one of which must be part of the current regimen, and current PI-based Anti-retroviral (ARV) medication regimen for at least 3 months prior to randomization. * HIV-1 viral load ≥1000 copies/mL at screening. * Further inclusion criteria apply. Exclusion criteria: * Anti-retroviral (ARV) medication naïve. * Patients on recent drug holiday, defined as off ARV medications for at least 7 consecutive days within the last 3 months. * Female patients of child-bearing potential who: * have a positive serum pregnancy test at screening or during the study, * are breast feeding, * are planning to become pregnant, * are not willing to a use barrier method of contraception, or * require ethinyl estradiol administration. * Prior tipranavir use. * Use of investigational medications within 30 days before study entry or during the trial. * Further exclusion criteria apply.