An ongoing study of metabolic abnormalities, body shape, and virologic and immunologic parameters in patients switched from protease inhibitor (PI)-containing to nevirapine (NVP)-containing regimens suggests that PIs may contribute to the development of lipodystrophy. At 14 months, patients who switched to NVP-containing regimens showed decreases in cholesterol, triglycerides, glucose, and fasting insulin resistance index. Additionally, waist/hip ratio decreased in subjects, although none of the patients subjectively acknowledged this improvement. Furthermore, patients had continued virologic and immune responses, with only 1 of 23 patients showing detectable viral load at 6 months. All of the improvements were observed regardless of the nucleoside reverse transcriptase inhibitors (NRTIs) used in the regimen (AZT, 9; d4T, 13; ddI, 7; ddC, 3; 3TC, 10).

Patients on d4T showed lower decreases in cholesterol and triglyceride levels compared to those receiving other NRTIs; however, data from the poster session indicate that d4T treated patients did not have the same elevations in laboratory parameters as did patients receiving AZT. Eight weeks after switching to NVP, patients receiving d4T had comparable triglyceride and cholesterol levels to those receiving AZT. However, the patients were not randomized, so selection bias may limit the study.