raltegravir + tenofovir disoproxil fumarate + lopinavir + ritonavir

A combination antiretroviral regimen used for the treatment of HIV infection. This regimen combines four different antiretroviral agents: raltegravir (an integrase strand transfer inhibitor), tenofovir disoproxil fumarate (a nucleotide reverse transcriptase inhibitor), and lopinavir/ritonavir (a protease inhibitor boosted with a pharmacokinetic enhancer). The PROGRESS study evaluated lopinavir/ritonavir combined with either raltegravir or tenofovir/emtricitabine in antiretroviral-naive adults over 96 weeks. Results showed similar efficacy between the two regimens, with 66.3% of subjects receiving LPV/r+RAL and 68.6% of subjects receiving LPV/r+TDF/FTC achieving plasma HIV-1 RNA levels below 40 copies/ml. Mean CD4+ T cell increases through 96 weeks were comparable between treatment groups (LPV/r+RAL=281 cells/mm³, LPV/r+TDF/FTC=296 cells/mm³). ## Safety Profile The safety profiles of these regimens showed some notable differences: - **Bone Health**: The LPV/r+RAL regimen showed significantly better bone mineral density outcomes compared to LPV/r+TDF/FTC (+0.68% vs. -2.48% change from baseline). - **Renal Function**: There was a statistically significantly greater mean reduction in estimated glomerular filtration rate in the LPV/r+TDF/FTC group compared with the LPV/r+RAL group (-7.33 ml/min vs. -1.43 ml/min). - **Body Composition**: The LPV/r+RAL regimen resulted in greater increases in peripheral fat, but not trunk fat, compared with LPV/r+TDF/FTC. ## Drug Interactions Lopinavir/ritonavir is a cytochrome P450 (CYP) 3A4 substrate and inhibitor with potential for multiple drug interactions. When using this combination, medication profiles should be carefully reviewed for potential interactions. Particular caution is needed with: - Fluticasone (should be avoided) - Antituberculous drugs (especially rifampin) - Other CYP3A4 substrates, inducers, or inhibitors. This combination represents an alternative antiretroviral regimen that may be beneficial in certain clinical scenarios, particularly where bone and renal health are concerns.