Background:  Raltegravir (RAL) is a 1^st in class integrase strand-transfer inhibitor. Metabolic parameters, including DEXA, were compared between RAL- and efavirenz (EFV)-based regimens after 96 weeks of treatment.

Methods:  Patients were randomized in a double-blind study of RAL vs EFV, each with TDF/FTC (n = 563). Groups were compared for metabolic parameters, including fasting lipid and glucose abnormalities according to DAIDS criteria, NCEP goals, and lipoatrophy (defined as ≤-20% change from baseline in appendicular fat) with follow-up through 96 week. DEXA scans were obtained on a subset of patients (n = 86) at baseline and Week 48, and on a subset of patients (n = 75) at both baseline and Week 96.

Results:  At Week 96, RAL had less impact on fasting lipids, including total, low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C) cholesterol levels, triglycerides as well as glucose than EFV; the impact on the total:HDL-C ratio was similar (Table 1). Fat changes by DEXA appear to be similar on average at Week 96 (Table 2). While the majority of Patients in both groups experienced modest fat gain, 3/37 patients on RAL and 2/38 patients on EFV had at least 20% appendicular fat loss (lipoatrophy).

Conclusions:  Through Week 96, RAL demonstrated minimal effects on serum lipids and glucose.  DEXA showed minimal gains in body fat, with no patterns of fat loss in both treatment groups. Longer-term experience with RAL suggests a favorable metabolic profile in treatment-naive patients.