Low concordance and resistance mutation emergence in the HIV protease gene among circulating and cell-associated viruses at viral replication episodes during darunavir/ritonavir monotherapy.

OBJECTIVE: To assess the changes on the HIV protease gene in plasma and peripheral blood mononuclear cell (PBMC) compartments during viral replication episodes in patients on boosted-darunavir monotherapy (mtDRV/rtv). METHODS: A prospective study was carried out in which adult HIV-1-infected patients who started mtDRV/rtv after viral suppression for ≥ 6 months with no major darunavir-related resistance mutations were enrolled. Patients with two consecutive plasma HIV RNA measurements >200 HIV-1 RNA copies/mL were considered as having virological failure (VF), while patients with two consecutive plasma HIV RNA measurements >50 copies/mL without meeting the VF criteria were considered to have virological rebound (VR). HIV protease genotypic profiles from plasma and PBMCs were performed at baseline and at VF and VR episodes. RESULTS: One hundred and fifty patients were included in the study, with overall VF and VR rates of 14% (n=21) and 14.7% (n=22), respectively. No major darunavir resistance mutations were observed in the plasma or PBMC samples. Circulating and cell-associated viruses showed a wild-type protease gene sequence in 54% and 23% of patients, respectively while the remainder patients only harboured minor protease inhibitor-associated mutations. Full concordance between plasma RNA and PBMC DNA protease genotypes was found in 23% of the sequences. CONCLUSIONS: No darunavir-related mutations were found in patients with VF or VR, either in plasma or in PBMCs; thus, simplification to mtDRV/rtv does not comprise future antiretroviral treatment options.

Impact of the peginterferon-α 2a and ribavirin plasma levels on viral kinetics and sustained virological response in genotype 1 HCV/HIV-co-infected patients with the unfavourable non-CC IL28B genotypes.

Studies on the association between the peginterferon-α and ribavirin levels and sustained virological response (SVR) have shown yielded conflicting results, but most of them were performed before the influence of IL28B polymorphisms was known. Our aim was to assess the effects of peginterferon-α 2a and ribavirin plasma levels on viral kinetics and SVR in hepatitis C virus genotype 1 HCV-1/HIV-co-infected patients according to IL28B genotype. This was a cohort study of HCV-1/HIV-co-infected patients who were HCV-treatment naïve and for whom the efficacy of peginterferon-α 2a plus ribavirin was evaluated by per-protocol analysis. The peginterferon-α 2a and ribavirin levels were measured by ELISA and HPLC-UV, respectively. The relationships among host and viral factors, the trough drugs levels and virological responses were analysed by multivariate regression analyses. A total of 131 Caucasian patients were included (cirrhosis:38.9%). Overall, SVR rate was 39.6%. In patients with CC IL28B genotype, SVR was related neither to peginterferon-α 2a nor to ribavirin plasma levels, while higher levels of both drugs were the only variables independently associated with SVR in individuals with CT/TT IL28B genotypes (OR, 5.02; CI95 , 1.45-17.1; P = 0.001 and 4.0; CI95 , 1.08-14.7; P = 0.038, respectively). Moreover, faster viral declines were observed in CT/TT patients when pegIFN-α 2a and ribavirin plasma levels were greater than 3400 pg/mL and 1.6 µg/mL, respectively. In contrast to the results for CC patients, the results in patients carrying the unfavourable CT/TT IL28B genotypes showed that plasma levels of both drugs have significant effects on viral kinetics and SVR.

Immune activation throughout a boosted darunavir monotherapy simplification strategy.

Our aim was to assess the evolution and the impact that blips, intermittent low-level viraemia and virological failure (VF) episodes have on patients' immune activation (IA) profiles during ritonavir-boosted darunavir monotherapy (mtDRV/rtv). A prospective cohort of human immunodeficiency virus-1-infected patients who switched to mtDRV/rtv was followed for 2 years. Cellular IA was assessed according to HLA-DR and CD38 expression in CD4(+) and CD8(+) T-cells and their naïve, effector memory and central memory subpopulations, and systemic IA was evaluated according to sCD14 and D-dimer levels. Seventy-five patients from the MonDAR cohort were selected for this substudy, and classified according to viral outcome as having continuous undetectable viraemia (n = 19), blips (n = 19), intermittent viraemia (n = 21), and VF (n = 16). The IA profile was closely linked to viral behaviour. Patients on viral suppression for 24 months showed a significant decrease in CD4(+) and CD8(+) T-cell activation and sCD14 and D-dimer levels. Patients with transient low-level viraemia episodes (blips and intermittent viraemia) showed cellular and systemic IA similar to baseline values. In contrast, significant increases in T-cell activation and sCD14 and D-dimer levels were observed in patients with VF. Baseline levels of HLA-DR(+)CD38(+)CD8(+) T-cells of >6.4% were independently associated with the emergence of VF. Therefore, mtDRV/rtv might be considered as a safe simplification strategy, on the basis of the IA results, whenever viral replication is under medium-term and long-term control. Transient low-level viraemia episodes do not affect patients' IA status. Moreover, HLA-DR(+)CD38(+)CD8(+) T-cell baseline levels should be considered when patients are switched to mtDRV/rtv.

Efficacy of daptomycin versus vancomycin in an experimental model of foreign-body and systemic infection caused by biofilm producers and methicillin-resistant Staphylococcus epidermidis.

Staphylococcus epidermidis is a frequent cause of device-associated infections. In this study, we compared the efficacy of daptomycin versus vancomycin against biofilm-producing methicillin-resistant S. epidermidis (MRSE) strains in a murine model of foreign-body and systemic infection. Two bacteremic biofilm-producing MRSE strains were used (SE284 and SE385). The MIC of daptomycin was 1 mg/liter for both strains, and the MICs of vancomycin were 4 and 2 mg/liter for SE284 and for SE385, respectively. The in vitro bactericidal activities of daptomycin and vancomycin were evaluated by using time-kill curves. The model of foreign-body and systemic infection of neutropenic female C57BL/6 mice was used to ascertain in vivo efficacy. Animals were randomly allocated into three groups (n = 15): without treatment (controls) or treated with daptomycin at 50 mg/kg/day or vancomycin at 440 mg/kg/day. In vitro, daptomycin showed concentration-dependent bactericidal activity, while vancomycin presented time-dependent activity. In the experimental in vivo model, daptomycin and vancomycin decreased liver and catheter bacterial concentrations (P < 0.05) and increased the survival and the number of sterile blood cultures (P < 0.05) using both strains. Daptomycin produced a reduction in the bacterial liver concentration higher than 2.5 log(10) CFU/g compared to vancomycin using both strains, with this difference being significant (P < 0.05) for infection with SE385. For the catheter bacterial concentrations, daptomycin reduced the concentration of SE284 3.0 log(10) CFU/ml more than did vancomycin (P < 0.05). Daptomycin is more effective than vancomycin for the treatment of experimental foreign-body and systemic infections by biofilm-producing methicillin-resistant S. epidermidis.

Role of pegylated interferon-alpha-2a and ribavirin concentrations in sustained viral response in HCV/HIV-coinfected patients.

The effect of simultaneous plasma concentrations of pegylated interferon-alpha-2a (pegIFN-alpha-2a) and ribavirin (Rbv) on viral response has not been addressed to date. Hepatitis C virus (HCV)/human immunodeficiency virus (HIV)-coinfected patients received pegIFN-alpha-2a and Rbv under routine clinical care conditions. Plasma concentrations of the two drugs were measured using enzyme-linked immunosorbent assay and high-performance liquid chromatography after 2, 4, 8, and 12 weeks and at the end of the treatment period (24-48 weeks, according to HCV genotype and treatment duration). Large interindividual variability was observed in the plasma levels of both drugs. After multivariate analysis, only HCV genotype 3, low HCV-RNA levels, and pegIFN-alpha-2a exposure remained as independent factors associated with sustained viral response (SVR). The probability of attaining an SVR in HCV genotypes 1 and 4 was more than three to four times higher in patients with pegIFN-alpha-2a levels above the selected cutoff point. Early therapeutic drug monitoring of pegIFN-alpha-2a levels could be beneficial in improving current treatment outcomes.

Intravitreal pharmacokinetics and retinal concentrations of ganciclovir and foscarnet after intravitreal administration in rabbits.

PURPOSE: To perform a detailed pharmacokinetic study and to evaluate the drug levels reached in the retina after the intravitreal administration of ganciclovir and foscarnet to rabbits. METHODS: Retinal and vitreal levels of both drugs were measured by high-performance liquid chromatography at 1, 6, 12, 24, 36, 48, 60, and 72 hours after a single intravitreal injection of 196 microg and 800 microg of ganciclovir and 960 microg of foscarnet to three groups of 24 pigmented rabbits. A noncompartmental pharmacokinetic analysis was used. RESULTS: Both drugs incorporated rapidly into the retina, but no equilibrium was observed between the drug levels in the vitreous humor and retina. Mean ganciclovir levels in vitreous and retina were 179.6 microg/g and 131.3 microg/g (dose of 196 microg), 755.7 microg/g and 381.6 microg/g (dose of 800 microg) at 1 hour after administration, decreasing to 0.1 microg/g, 0.6 microg/g, 0.8 microg/g, and 0.7 microg/g, respectively, by 72 hours. Mean foscarnet levels in vitreous and retina were 944 microg/g and 217.1 microg/g at 1 hour after administration, decreasing to 74 microg/g and 17.1 microg/g, respectively, by 72 hours. Whereas both doses of ganciclovir yielded retinal levels above the mean inhibitory concentration (IC50) of most human cytomegalovirus (CMV) isolates for more than 60 hours, foscarnet retinal levels were lower than the CMV IC50 before 36 hours had elapsed after administration. CONCLUSIONS: The results suggest that the intravitreal administration of ganciclovir has a better pharmacokinetic profile than foscarnet for the treatment of retinitis caused by CMV and other herpes viruses and support the administration of intravitreal ganciclovir twice a week as a treatment for CMV retinitis.

Intravitreal, retinal, and central nervous system foscarnet concentrations after rapid intravenous administration to rabbits.

Retinal, vitreous humor, brain, and cerebrospinal fluid (CSF) foscarnet levels were measured by high-performance liquid chromatography after administration of an intravenous dose of 120 mg/kg of body weight to 32 pigmented rabbits. A pharmacokinetic analysis was done using a two-compartment model. The penetration ratios, defined as ratios of retinal, vitreous humor, brain, and CSF areas under the concentration-time curve from 0 to 2 h were 110% +/- 1%, 12.3% +/- 0.7%, 118% +/- 1%, and 20.2% +/- 2.2%, respectively. These results suggest a good penetration of foscarnet into the retinal and brain tissues, reaching higher concentrations than those estimated from vitreous humor and CSF levels.