Safety and efficacy of treatment switch to raltegravir plus tenofovir/emtricitabine or abacavir/lamivudine in patients with optimal virological control: 48-week results from a randomized pilot study (Raltegravir Switch for Toxicity or Adverse Events, RASTA Study).

BACKGROUND: The Raltegravir Switch for Toxicity or Adverse Events (RASTA) Study is a 2-arm randomized pilot study exploring the safety and efficacy at 48 weeks of a treatment switch to raltegravir associated with tenofovir/emtricitabine or abacavir/lamivudine in patients with regimens with optimal virological control. METHODS: Patients treated with stable protease inhibitor (PI)-, non-nucleoside reverse transcriptase inhibitor (NNRTI)-, or nucleoside reverse transcriptase inhibitor (NRTI)-based regimens, with HIV-RNA levels < 50 copies/ml for ≥ 3 months and a CD4 cell count > 200 cells/µl were eligible. Enrollment of 40 patients was planned: at baseline patients were randomized 1:1 to switch to raltegravir plus tenofovir/emtricitabine (arm A) or abacavir/lamivudine (arm B). Laboratory parameters, raltegravir plasma levels, self- reported adherence, quality of life parameters, neurocognitive performance, bone composition, and body fat distribution were monitored. Virological failure was defined as HIV-RNA > 50 copies/ml on 2 consecutive determinations. RESULTS: After 48 weeks, 5/40 (12.5%) regimen discontinuations occurred: 2 were for low-level viremia virological failure (both in arm A, at weeks 24 and 48) and 3 were for adverse events (neurological disturbances and skin rash in arm B; proximal tubulopathy in arm A). Overall, a significant CD4 increase was observed at weeks 36 and 48, and a significant decrease in total cholesterol, non-high density lipoprotein cholesterol, and triglycerides was observed at each study visit. Physical health/satisfaction in therapy scores and neuropsychological performance improved. The lumbar column Z-score improved, with no modification in other bone composition and fat distribution parameters. CONCLUSIONS: The investigated switch strategy was associated with rare virological failure. Improvements in lipid levels, quality of life measures, neuropsychological performance, and bone composition suggest good tolerability of raltegravir-based regimens.

The role of small intestinal bacterial overgrowth in Parkinson's disease.

Parkinson's disease is associated with gastrointestinal motility abnormalities favoring the occurrence of local infections. The aim of this study was to investigate whether small intestinal bacterial overgrowth contributes to the pathophysiology of motor fluctuations. Thirty-three patients and 30 controls underwent glucose, lactulose, and urea breath tests to detect small intestinal bacterial overgrowth and Helicobacter pylori infection. Patients also underwent ultrasonography to evaluate gastric emptying. The clinical status and plasma concentration of levodopa were assessed after an acute drug challenge with a standard dose of levodopa, and motor complications were assessed by Unified Parkinson's Disease Rating Scale-IV and by 1-week diaries of motor conditions. Patients with small intestinal bacterial overgrowth were treated with rifaximin and were clinically and instrumentally reevaluated 1 and 6 months later. The prevalence of small intestinal bacterial overgrowth was significantly higher in patients than in controls (54.5% vs. 20.0%; P = .01), whereas the prevalence of Helicobacter pylori infection was not (33.3% vs. 26.7%). Compared with patients without any infection, the prevalence of unpredictable fluctuations was significantly higher in patients with both infections (8.3% vs. 87.5%; P = .008). Gastric half-emptying time was significantly longer in patients than in healthy controls but did not differ in patients based on their infective status. Compared with patients without isolated small intestinal bacterial overgrowth, patients with isolated small intestinal bacterial overgrowth had longer off time daily and more episodes of delayed-on and no-on. The eradication of small intestinal bacterial overgrowth resulted in improvement in motor fluctuations without affecting the pharmacokinetics of levodopa. The relapse rate of small intestinal bacterial overgrowth at 6 months was 43%. © 2013 Movement Disorder Society.

Validation of an UPLC-MS/MS method for quantitative analysis of raltegravir in human plasma samples.

BACKGROUND: An ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the quantification of raltegravir (RTG) plasma concentrations in samples from HIV patients treated with the drug. METHODS: Plasma samples were extracted by liquid-liquid extraction followed by evaporation to dryness and reconstitution in mobile phase. The chromatographic separation was carried out on an AQUITY UPLC C18 column with an isocratic mobile phase consisting of water containing 0.1% formic acid and acetonitrile containing 0.1% formic acid (50:50 vol/vol). The detection was performed on a triple quadrupole tandem mass spectrometer using multi-reaction monitoring via electrospray ionization source with positive ionization mode. RESULTS: Under these conditions, a single chromatographic run could be completed within 1 minute. The method was validated by estimating the precision and the accuracy for inter- and intra-day analysis in the concentration range of 5-2560 ng/mL. The method was linear over the investigated range with all the correlation coefficients, r, greater than 0.995 on 5 replicates. The intra- and inter-day precision (percentage of coefficient of variation) ranged from 2.4% to 11.2%, and the inaccuracy (percent of relative standard deviation) ranged from 2.5% to 12.9%. No significant matrix effect was observed. The mean recovery value of RTG was 80%. CONCLUSIONS: This rapid and sensitive method was validated and could be applied to pharmacokinetic studies for the determination of RTG concentrations in human plasma samples.

Variability of raltegravir plasma levels in the clinical setting.

Therapeutic drug monitoring of raltegravir Ctrough levels was carried out in the setting of the Raltegravir Switch for Toxicity or Adverse events (RASTA) trial, a randomized pilot study exploring a 48-week safety and efficacy of treatment switch to raltegravir associated with tenofovir/emtricitabine or abacavir/lamivudine in patients with regimens with optimal virologic control. Blood sampling for measurement of raltegravir plasma levels was carried out at weeks 4, 12, 24, 36 and 48. Plasma samples were analysed by a recently developed and validated UPLC-MS method. A total of 164 samples from 39 patients were assayed. Analysis for intra- and inter-subject variability was restricted to those patients with 4 or more determinations, including 30 patients and 142 determinations. The intra- and inter-subject variability measures were 85.9 and 124.6%, respectively, with an intra-/inter-subject variability ratio of 69%. We also analysed data from a subset of patients with well-documented adherence to protocol, defined as protocol compliant population, including 21 patients and 93 determinations. In this subpopulation, we estimated intra- and inter-subject variability of 79.87% and 110%, respectively, with an intra-/inter-subject variability ratio of 72.6%. This study confirms the notion that raltegravir is a highly variable drug according to the European Medicines Agency criteria. While this condition does not favour the adoption of therapeutic drug monitoring in the clinical practice, the latter is deemed useful in patients with drug plasma concentrations below or near the threshold level of efficacy (since intracellular raltegravir levels might be as low as 5% of the corresponding plasma levels), or to identify drug-drug interactions of potential clinical relevance.

Validation of a new HPLC-UV method for determination of the antibiotic linezolid in human plasma and in bronchoalveolar lavage.

A rapid and selective HPLC-UV method was developed for the quantification of linezolid (LNZ) in human plasma and bronchoalveolar lavage (BAL) at the concentrations associated with therapy. Plasma samples were extracted by solid-phase extraction followed by evaporation to dryness and reconstitution in mobile phase solution. The chromatographic separation was carried out on a C18 column with an isocratic mobile phase consisting of dihydrogen phosphate buffer 50 mm (pH 3.5) and acetonitrile (60:40 v/v). The detection was performed using a photodiode array. Under these conditions, a single chromatographic run could be completed within 12 min. The method was validated by estimating the precision and the accuracy for inter- and intra-day analysis in the concentration range of 25-25600 ng/mL. The method was linear over the investigated range with all the correlation coefficients R > 0.999. The intra- and inter-day precision was within 8.90% and the accuracy ranged from -4.76 to +5.20%. This rapid and sensitive method was fully validated and could be applied to pharmacokinetic study for the determination of LNZ levels in human plasma and BAL samples.

Linezolid plasma and intrapulmonary concentrations in critically ill obese patients with ventilator-associated pneumonia: intermittent vs continuous administration.

PURPOSE: Clinical application of an antibiotic's pharmacokinetic/pharmacodynamic (PK/PD) properties may improve the outcome of severe infections. No data are available on the use of linezolid (LNZ) continuous infusion in critically ill obese patients affected by ventilator-associated pneumonia (VAP). METHODS: We conducted a prospective randomized controlled trial to compare LNZ concentrations in plasma and epithelial lining fluid (ELF), when administered by intermittent and continuous infusion (II, CI), in obese critically ill patients affected by VAP. RESULTS: Twenty-two critically ill obese patients were enrolled. At the steady state, in the II group, mean ± SD total and unbound maximum-minimum concentrations (C max/C max,u - C min/Cmin,u) were 10 ± 3.7/6.8 ± 2.6 mg/L and 1.7 ± 1.1/1.2 ± 0.8 mg/L, respectively. In the CI group, the mean ± SD total and unbound plasma concentrations (C ss and C ss,u) were 6.2 ± 2.3 and 4.3 ± 1.6 mg/L, respectively. Within a minimum inhibitory concentration (MIC) range of 1-4 mg/L, the median (IQR) time LNZ plasma concentration persisted above MIC (% T > MIC) was significantly higher in the CI than the II group [100 (100-100) vs 100 (89-100), p = 0.05; 100 (100-100) vs 82 (54.8-98.8), p = 0.009; 100 (74.2-100) vs 33 (30.2-78.5), p = 0.005; respectively]. Pulmonary penetration (%) was higher in the CI group, as confirmed by a Monte Carlo simulation [98.8 (IQR 93.8-104.3) vs 87.1 (IQR 78.7-95.4); p < 0.001]. CONCLUSIONS: In critically ill obese patients affected by VAP, LNZ CI may overcome the limits of standard administration but these advantages are less evident with difficult to treat pathogens (MIC = 4 mg/L). These data support the usefulness of LNZ continuous infusion, combined with therapeutic drug monitoring (TDM), in selected critically ill populations.

Kinetics of hepatitis C virus RNA decay, quasispecies evolution and risk of virological failure during telaprevir-based triple therapy in clinical practice.

BACKGROUND: The used first generation protease inhibitors may be hampered by virological failure in partially interferon-sensitive patients. AIM: To investigate early hepatitis C virus (HCV)-RNA decay and quasispecies modifications, and disclose viral dynamics underlying failure. METHODS: Viraemia decay at early time-points during telaprevir treatment was modelled according to Neumann et al. (1998). NS3-sequences were obtained by population-sequencing and ultradeep-454-pyrosequencing. RESULTS: 13 treatment-experienced (8 non-responders, 5 relapsers), and two cirrhotic naïve patients, received telaprevir+pegylated-interferon-α+ribavirin. Viraemia decay was biphasic. In all patients, first-phase was rapid and consistent, with a median [interquartile-range] viraemia decay of 2.8 [2.6-3.2]logIU/ml within 48h. Second-phase decay was slower, especially in failing patients: 3/3 showed <1logIU/ml decay between 48h and 2 weeks, and HCV-RNA >100IU/ml at week 2. Only one patient experiencing sustained viral response showed similar kinetics. By pyrosequencing, mutational freeze was observed in all 15 patients within the first 24h, but only in patients with sustained response afterwards. Indeed, 2/2 failing patients showed early resistance, as minor (V36A-T54A: prevalence <26% at 48h) or major (V36M/A-R155K: prevalence, 99.8% at week 2) variants. CONCLUSIONS: Following telaprevir administration, first-phase HCV-RNA decay is consistent with mutational freeze and limited/no viral replication, while second-phase is significantly slower in failing patients (with appearance of resistance), suggesting the usefulness of early HCV-RNA monitoring.

Liquid melevodopa versus standard levodopa in patients with Parkinson disease and small intestinal bacterial overgrowth.

OBJECTIVES: Patients with Parkinson disease exhibit a highly increased prevalence of small intestinal bacterial overgrowth (SIBO), which has been also associated with the severity of motor fluctuations. Aim of this study was to test the efficacy of liquid levodopa with higher bioavailability in patients with SIBO. METHODS: Thirty-three patients with Parkinson disease underwent both lactulose and glucose breath tests to assess the presence of SIBO. A urea breath test was performed to assess the presence of a concomitant Helicobacter pylori infection. Patients were challenged with 250 mg of levodopa and 314 mg of levodopa methylester. Drug challenges were performed on different days and at baseline and 1 month after SIBO eradication. During the tests, the motor condition and the plasma levodopa concentrations were evaluated. RESULTS: At baseline, the onset of motor benefit was significantly shorter after melevodopa than after standard levodopa, as confirmed by the latency to motor on condition and t max (time to the on condition, 28.8±11.5 vs 55.5±40.2 minutes; P=0.0004; and t max, 28.2±9.7 vs 50.0±11.0 minutes; P=0.002). The duration of the on time or area under the curve was not significantly different. The underlying gastrointestinal condition did not influence these results. CONCLUSIONS: The reduction of the latency to the on condition in the absence of a reduction of the on duration is a promising feature of melevodopa because this effect would increase the total daily on duration. Future studies that evaluate the usefulness of melevodopa beyond the acute challenge (eg, using motor diaries) in patients with gastrointestinal infections are warranted.