• The frequency of treatment-emergent adverse events (AEs), all serious AEs, and additional safety laboratory parameters
  
• The occurrence of PI class-specific AEs, such as hemorrhage, dyslipidemia, hepatic events, hyperglycemia, pancreatitis, and rash
  

• The quantity of HIV-1 RNA
  
• The CD4 cell count
  

The purpose of this open label study is to assess the safety and tolerability of tipranavir co-administered with low-dose ritonavir (500 mg tipranavir/200 mg ritonavir BID) in HIV-1 infected patients who are triple antiretroviral class experienced with at least two previous PI-containing regimens.

The safety assessment will be performed by evaluating:

• The frequency of treatment-emergent adverse events (AEs) , all serious adverse events (SAEs), and additional safety laboratory parameters.
• The occurrence of PI class-specific AEs, such as hemorrhage, dyslipidemia, hepatic events, hyperglycemia, pancreatitis, and rash.

The efficacy assessment will be performed by evaluating:

• The quantity of HIV-1 RNA
• The CD4 cell count.

Study Hypothesis:

The purpose of this open label study is to assess the safety and tolerability of tipranavir co-administered with low-dose ritonavir (500 mg tipranavir/200 mg ritonavir BID) in HIV-1 infected patients who are triple antiretroviral class experienced with at least two previous PI-containing regimens.

Comparison(s):

N.A.

Inclusion Criteria:

1. Triple antiretroviral class experienced patients with at least two previous PI-based regimens, who had failed or are intolerant to currently approved HIV-1 treatments
2. Age >= 18 years
3. Patient is willing to use an effective barrier method of contraception for the duration of study participation and up to three months thereafter
4. Patient voluntarily provides written informed consent to participate, in compliance with local law

Exclusion Criteria:

1. Hypersensitivity to active ingredients or any of the excipients in tipranavir or ritonavir
2. Required use of restricted medications

3. Female patients of childbearing potential who:

   • Have a positive pregnancy test at baseline or
   • Are breast feeding.
4. Any medical condition(s) which, in the opinion of the investigator, would interfere with the patient´s ability to participate in or adhere to the requirements of this protocol.
5. Use of other investigational drugs, within 30 days prior to TPV/r initiation and for the duration of study participation.

6. Hepatic impairment(*) evidenced by the following baseline laboratory findings:

   • AST or ALT >5X upper limit of normal (ULN) or total bilirubin >3.5X ULN or
   • AST or ALT >2.5X ULN and total bilirubin >2X ULN

(*) Patients with liver enzymes outside this range will be restricted from participation in this safety study until more data become available from ongoing phase III clinical studies.