The primary purpose of the study is to assess the safety and pharmacokinetics of KP-1461 given every 12 hours for 14 days when administered to HIV+ patients who have failed multiple highly active antiretroviral therapy (HAART) regimens. Patients currently on HAART will be required to discontinue all HAART medications for up to 6 weeks after screening eligibility has been determined.

KP-1461 is a carbamate prodrug of the active nucleoside, KP-1212. KP-1212 is incorporated into the proviral DNA. After multiple rounds of replication, KP-1212 increases the high inherent mutation rate of HIV beyond the threshold of viability, a process called "viral decay acceleration". KP-1212 is unique from conventional nucleoside reverse transcriptase inhibitors in that it inserts mutations randomly across the entire 10,000 nucleotide HIV genome and does not exert selective pressure by targeting a specific viral or cellular process, thus potentially avoiding drug resistance.

Inclusion Criteria:

• CD4 > 100 cells/mm3
• Viral load 2,500 - 200,000 copies/mL
• Exposure to at least 2 different HAART regimens containing NRTI(s), NNRTI(s), and 2 PI(s), excluding Ritonavir, for a minimum of 4 months or documented resistance to at least 3 of the 4 classes of approved antiretroviral drugs.
• Few, if any, effective treatment options available

Exclusion Criteria:

• HBsAb (hepatitis B) positive serology