Effects of omeprazole on plasma levels of raltegravir.

Raltegravir, a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor, has pH-dependent solubility. Raltegravir plasma concentration increases with omeprazole coadministration in healthy subjects; this is likely secondary to an increase in bioavailability attributable to increased gastric pH. Increased gastric pH has been reported in HIV-1-infected individuals, and the effects of omeprazole in this intended population may be diminished. Further investigation is necessary.

Minimal effects of ritonavir and efavirenz on the pharmacokinetics of raltegravir.

Raltegravir is a novel human immunodeficiency virus type 1 (HIV-1) integrase strand transfer inhibitor with potent in vitro activity against HIV-1 (95% inhibitory concentration = 31 nM in 50% human serum). The possible effects of ritonavir and efavirenz on raltegravir pharmacokinetics were separately examined. Two clinical studies of healthy subjects were conducted: for ritonavir plus raltegravir, period 1, 400 mg raltegravir; period 2, 100 mg ritonavir every 12 h for 16 days with 400 mg raltegravir on day 14; for efavirenz plus raltegravir, period 1, 400 mg raltegravir; period 2, 600 mg efavirenz once daily for 14 days with 400 mg raltegravir on day 12. In the presence of ritonavir, raltegravir pharmacokinetics were weakly affected: the plasma concentration at 12 h (C(12 h)) geometric mean ratio (GMR) (90% confidence interval [CI]) was 0.99 (0.70, 1.40), area under the concentration-time curve from zero to infinity (AUC(0-infinity)) was 0.84 (0.70, 1.01), and maximum concentration of drug in serum (C(max)) was 0.76 (0.55, 1.04). In the presence of efavirenz, raltegravir pharmacokinetics were moderately to weakly reduced: C(12 h) GMR (90% CI) was 0.79 (0.49, 1.28); AUC(0-infinity) was 0.64 (0.52, 0.80); and C(max) was 0.64 (0.41, 0.98). There were no substantial differences in the time to maximum concentration of drug in plasma or the half-life. Plasma concentrations of raltegravir were not substantially affected by ritonavir. Though plasma concentrations of raltegravir were moderately to weakly reduced by efavirenz, the degree of this reduction was not clinically meaningful. No dose adjustment is required for raltegravir with coadministration with ritonavir or efavirenz.

Atazanavir modestly increases plasma levels of raltegravir in healthy subjects.

Raltegravir is an HIV integrase inhibitor that is metabolized through glucuronidation by uridine diphosphate glucuronosyltransferase 1A1, and its use is anticipated in combination with atazanavir (a uridine diphosphate glucuronosyltransferase 1A1 inhibitor). Two pharmacokinetic studies of healthy subjects assessed the effect of multiple-dose atazanavir or ritonavir-boosted atazanavir on raltegravir levels in plasma. Atazanavir and atazanavir plus ritonavir modestly increase plasma levels of raltegravir.

A double-blind, randomized, controlled, multicenter safety and immunogenicity study of a refrigerator-stable formulation of Zostavax.

The vaccine Zostavax has been shown to prevent herpes zoster (HZ) and postherpetic neuralgia and is recommended for individuals > or =60 years of age. This study compared the safety and the immunogenicity of a refrigerator-stable formulation (Zostavax refrigerated) with those of the current formulation (Zostavax frozen) in subjects > or =50 years of age. Subjects with a negative history for HZ were randomized 1:1 to receive one dose of either formulation. Enrollment was stratified 1:2 by age (50 to 59 years and > or =60 years). Safety was evaluated for 28 days postvaccination. Varicella-zoster virus (VZV) antibody responses were measured by a glycoprotein enzyme-linked immunosorbent assay (gpELISA). The primary endpoints were the VZV antibody geometric mean titer (GMT; day 28), the VZV antibody geometric mean rise (GMR; days 1 to 28), and the incidence of vaccine-related serious adverse experiences (AEs) over 28 days. The refrigerated (n = 182) and frozen (n = 185) formulations induced similar GMTs (727.4 and 834.4 gpELISA units/ml, respectively); the estimated GMT ratio (refrigerated formulation/frozen formulation) was 0.87 (95% confidence interval, 0.71 to 1.07). The GMRs were 2.6- and 2.9-fold, respectively. No vaccine-related serious AEs were reported in either group, and the safety profiles of the formulations were generally similar. The frequencies of injection-site AEs during follow-up were 35.6% and 46.4% in the refrigerated and the frozen formulation groups, respectively, and were generally mild. The frequencies of systemic AEs were similar in the two groups, and those of vaccine-related AEs were approximately 6% in both groups. The refrigerator-stable formulation of Zostavax has an acceptable safety profile and is as immunogenic as the frozen formulation; thus, the vaccine may be used in clinical settings where freezer availability is limited.

Metabolism and disposition in humans of raltegravir (MK-0518), an anti-AIDS drug targeting the human immunodeficiency virus 1 integrase enzyme.

Raltegravir is a potent human immunodeficiency virus 1 (HIV-1) integrase strand transfer inhibitor that is being developed as a novel anti-AIDS drug. The absorption, metabolism, and excretion of raltegravir were studied in healthy volunteers after a single oral dose of 200 mg (200 microCi) of [(14)C]raltegravir. Plasma, urine, and fecal samples were collected at specified intervals up to 240 h postdose, and the samples were analyzed for total radioactivity, parent compound, and metabolites. Radioactivity was eliminated in substantial amounts in both urine (32%) and feces (51%). The elimination of radioactivity was rapid, since the majority of the recovered dose was attributable to samples collected through 24 h. In extracts of urine, two components were detected and were identified as raltegravir and the glucuronide of raltegravir (M2), and each accounted for 9% and 23% of the dose recovered in urine, respectively. Only a single radioactive peak, which was identified as raltegravir, was detected in fecal extracts; raltegravir in feces is believed to be derived, at least in part, from the hydrolysis of M2 secreted in bile, as demonstrated in rats. The major entity in plasma was raltegravir, which represented 70% of the total radioactivity, with the remaining radioactivity accounted for by M2. Studies using cDNA-expressed UDP-glucuronosyltransferases (UGTs), form-selective chemical inhibitors, and correlation analysis indicated that UGT1A1 was the main UGT isoform responsible for the formation of M2. Collectively, the data indicate that the major mechanism of clearance of raltegravir in humans is UGT1A1-mediated glucuronidation.

Protective effect of the immunosuppressant sirolimus against aortic atherosclerosis in apo E-deficient mice.

Atherosclerosis is a chronic inflammatory disease that develops in response to injury to the vessel wall, and is augmented by hypercholesterolemia. To further delineate the role of the immune system and local factors in this process, we assessed the effects of the immunosuppressant sirolimus (Rapamycin, RAPAMUNE, Wyeth, Collegeville, PA) on atherosclerosis in the apoE-deficient (apoE KO) mouse, a well-accepted model of cardiovascular disease. ApoE KO mice were fed a high fat diet and sirolimus was administered. After 12 weeks, atherosclerotic lesions and plasma lipoproteins were measured. The expression of cytokines associated with atherosclerosis was also examined. All groups demonstrated plasma total cholesterol (TC) >1100 mg/dL. Sirolimus treatment was associated with a 30% increase in LDL-cholesterol (LDLc) and a dose-dependent elevation in HDL-cholesterol (HDLc). Despite increased LDLc, aortic atherosclerosis was markedly reduced in all sirolimus-treated groups. Sirolimus treatment resulted in decreased expression of IL-12p40, IFN-gamma and IL-10 mRNA. In contrast, TGF-beta1 was elevated. Sirolimus significantly reduced atherosclerosis in apo E-KO mice; this effect is independent of, and obviates, elevated plasma TC and LDLc. Sirolimus might therefore be of benefit on atherosclerosis in patients undergoing therapy, independent of any impact on circulating lipids.