Traditional Cultures versus Next Generation Sequencing for Suspected Orthopedic Infection: Experience Gained from a Reference Centre.

(Background) The diagnosis and the antimicrobial treatment of orthopedic infection are challenging, especially in cases with culture-negative results. New molecular methods, such as next-generation sequencing (NGS), promise to overcome some limitations of the standard culture, such as the detection of difficult-to-grow bacteria. However, data are scarce regarding the impact of molecular techniques in real-life scenarios. (Methods) We included cases of suspected orthopedic infection treated with surgery from May 2021 to September 2023. We combined traditional cultures with NGS. For NGS, we performed a metagenomic analysis of ribosomal 16s, and we queried dedicated taxonomic libraries to identify the species. To avoid false positive results, we set a cut-off of 1000 counts of the percentage of frequency of reads. (Results) We included 49 patients in our study. Our results show the presence of bacteria in 36/49 (73%) and 29/49 (59%) cases studied with NGS and traditional cultures, respectively. The concordance rate was 61%. Among the 19/49 discordant cases, in 11/19 cases, cultures were negative and NGS positive; in 4/19, cultures were positive and NGS negative; and in the remaining 4/19, different species were detected by traditional cultures and NGS. (Conclusions) Difficult-to-grow microorganisms, such as slow-growing anaerobic bacteria, were better detected by NGS compared to traditional culture in our study. However, more data to distinguish between true pathogens and contaminants are needed. NGS can be an additional tool to be used for the diagnosis of orthopedic infections and the choice of appropriate antimicrobial therapy.

Comparison of three therapeutic regimens for genotype-3 hepatitis C virus infection in a large real-life multicentre cohort.

BACKGROUND & AIMS: In the direct-acting antiviral era, treatment of genotype-3 HCV (HCV-GT3) is still challenging. Real-life comparisons between recommended regimens, sofosbuvir (SOF)+daclatasvir (DAC), SOF/velpatasvir (VEL), glecaprevir/pibrentasvir (GLE/PIB), are scarce. We aimed at filling this data gap. METHODS: Sustained virological response 12 weeks after treatment completion (SVR12) was assessed for all HCV-GT3 patients consecutively treated within the Lombardia web-based Navigatore HCV-Network; differences in SVR12 across regimens were evaluated by logistic regression. RESULTS: Of the 2082 subjects with HCV-GT3, 1544 were evaluable for comparisons between regimens: SOF + DAC (1023, 66.2%), SOF/VEL (369, 23.9%), GLE/PIB (152, 9.8%). Patients treated with former regimens were more frequently male, cirrhotic, HIV-positive, pretreated, used ribavirin in their regimen, and had lower baseline HCV-RNA. SVR12 was similar across groups: 94.8% in SOF + DAC, 97.6% in SOF/VEL, 96.7% in GLE/PIB (P = .065). At univariate analysis, SVR12 was associated with female gender (97.9% vs 94.8%, P = .007) and lower median pretreatment Log10 HCV-RNA (5.87 vs 6.20, P = .001). At multivariate logistic regression analysis, treatment with SOF/VEL was associated with a higher likelihood of SVR12 than SOF + DAC, but only in the absence of ribavirin (98% vs 90.3%). Female gender and lower pretreatment HCV-RNA were independently associated with SVR12. CONCLUSIONS: In a large real-life setting of HCV-GT3-infected patients with a high proportion of cirrhosis, the success rate was remarkable. The slight advantage of SOF/VEL on SOF + DAC was significant only without ribavirin. The current prescription shift towards novel regimens (ie SOF/VEL and GLE/PIB) in easier-to-treat patients allows ribavirin-free and shorter schedules without mining SVR12 in this <> genotype.

Real-life effectiveness and safety of sofosbuvir/velpatasvir/voxilaprevir in hepatitis C patients with previous DAA failure.

BACKGROUND & AIMS: Sofosbuvir/velpatasivr/voxilaprevir (SOF/VEL/VOX) is approved for retreatment of patients with HCV and a previous failure on direct-acting antivirals (DAAs), however real-life data are limited. The aim of this study was to assess the effectiveness and safety of SOF/VEL/VOX in a real-life setting. METHODS: All consecutive patients with HCV receiving SOF/VEL/VOX between May-October 2018 in 27 centers in Northern Italy were enrolled. Bridging fibrosis (F3) and cirrhosis (F4) were diagnosed by liver stiffness measurement: >10 and >13 kPa respectively. Sustained virological response (SVR) was defined as undetectable HCV-RNA 4 (SVR4) or 12 (SVR12) weeks after the end-of-treatment. RESULTS: A total of 179 patients were included: median age 57 (18-88) years, 74% males, median HCV-RNA 1,081,817 (482-25,590,000) IU/ml. Fibrosis stage was F0-F2 in 32%, F3 in 21%, F4 in 44%. HCV genotype was 1 in 58% (1b 33%, 1a 24%, 1nc 1%), 2 in 10%, 3 in 23% and 4 in 9%; 82% of patients carried resistance-associated substitutions in the NS3, NS5A or NS5B regions. Patients received SOF/VEL/VOX for 12 weeks, ribavirin was added in 22% of treatment schedules. Undetectable HCV-RNA was achieved by 74% of patients at week 4 and by 99% at week 12. Overall, 162/179 (91%) patients by intention to treat analysis and 162/169 (96%) by per protocol analysis achieved SVR12, respectively; treatment failures included 6 relapsers and 1 virological non-responder. Cirrhosis (p = 0.005) and hepatocellular carcinoma (p = 0.02) were the only predictors of treatment failure. Most frequent adverse events included fatigue (6%), hyperbilirubinemia (6%) and anemia (4%). CONCLUSIONS: SOF/VEL/VOX is an effective and safe retreatment for patients with HCV who have failed on a previous DAA course in a real-life setting. LAY SUMMARY: This is the largest European real-life study evaluating effectiveness and safety of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) in a large cohort of consecutive patients with hepatitis C virus infection and a prior direct-acting antiviral failure, who were treated within the NAVIGATORE Lombardia and Veneto Networks, in Italy. This study demonstrated excellent effectiveness (98% and 96% sustained virological response rates at week 4 and 12, respectively) and an optimal safety profile of SOF/VEL/VOX. Cirrhosis and hepatocellular carcinoma onset were the only features associated with treatment failure.

Real-world effectiveness and safety of glecaprevir/pibrentasvir in 723 patients with chronic hepatitis C.

BACKGROUND AND AIMS: The efficacy and safety of glecaprevir/pibrentasvir (G/P) for patients infected with hepatitis C virus (HCV) have only been investigated in clinical trials, with no real-world data currently available. The aim of our study was to investigate the effectiveness and safety of G/P in a real-world setting. METHODS: All patients with HCV consecutively starting G/P between October 2017 and January 2018 within the NAVIGATORE-Lombardia Network were analyzed. G/P was administered according to drug label (8, 12 or 16 weeks). Fibrosis was staged either histologically or by liver stiffness measurement. Sustained virological response (SVR) was defined as undetectable HCV-RNA 12 weeks after the end of treatment. RESULTS: A total of 723 patients (50% males) were treated with G/P, 89% for 8 weeks. The median age of our cohort was 58 years, with a median body mass index of 23.9 kg/m2, and median liver stiffness measurement of 6.1 kPa; 84% were F0-2 and 16% were interferon-experienced. Median HCV-RNA was 1,102,600 IU/ml, and 49% of patients had HCV genotype 1 (32% 1b), 28% genotype 2, 10% genotype 3 and 13% genotype 4. The median estimated glomerular filtration rate was 90.2 ml/min, platelet count 209x103/mm3 and albumin 4.3 g/dl. The SVR rates were 94% in intention-to-treat and 99.3% in per protocol analysis (8-week vs. 12 or 16-week: 99.2% vs. 100%). Five patients failed therapy because of post-treatment relapse; a post-treatment NS5A resistance-associated substitution was detected in 1 case. SVR rates were lower in males (p = 0.002) and in HCV genotype-3 (p = 0.046) patients treated for 8 weeks, but independent of treatment duration, fibrosis stage, baseline HCV-RNA, HIV co-infection, chronic kidney disease stage and viral kinetics. Mild adverse events were reported in 8.3% of the patients, and 0.7% of them prematurely withdrew treatment. Three patients died of drug-unrelated causes. CONCLUSIONS: In a large real-world cohort of Italian patients, we confirmed the excellent effectiveness and safety of G/P administered for 8, 12 or 16 weeks. LAY SUMMARY: A large number of patients with hepatitis C virus have been treated with glecaprevir/pibrentasvir (G/P) within the NAVIGATORE-Lombardia Network, in Italy. This is the first real-world study evaluating effectiveness and safety of G/P in patients with hepatitis C virus treated according to international recommendations. This study demonstrated excellent effectiveness (with sustained virological response rates of 99.3%) and safety profiles.

Are direct-acting antivirals safe and effective in hepatitis C virus-cryoglobulinemia? virological, immunological, and clinical data from a real-life experience.

OBJECTIVES: Hepatitis C virus (HCV) is the major cause of cryoglobulinemia. Direct-acting antivirals (DAAs) have markedly changed the therapeutic outcomes in the treatment of patients with HCV. We evaluate the efficacy, safety, immunological, and clinical response of different DAA regimens in HCV-cryoglobulinemia. PATIENTS AND METHODS: Ninety-three cryoglobulinemic patients, divided into symptomatic [symptomatic cryoglobulinemic patients (SCP; n=35)] and asymptomatic [nonsymptomatic cryoglobulinemic patients (NSCP; n=60)], underwent DAAs. Eighty-nine comparable noncryoglobulinemic patients were selected as a control group. We evaluated the sustained virological response (SVR), the adverse effects, and the immune and symptomatic response. RESULTS: Percentages of patients who achieved SVR and experienced adverse effects were not statistically different between the three groups (100, 95, 93.3% and 57.1, 53.3, 48.3%). In 68.5% of SCP and in 76.7% of NSCP, cryoglobulins disappeared at SVR. No risk factor was associated with the persistence of cryoglobulins. An increase was observed both in C4 (P=0.002; P=0.018) and in C3 (P=0.0037; P=0.031) in SCP and NSCP. About 70% of symptomatic patients showed a complete or partial symptomatic remission: persistence of symptoms is correlated to the type of clinical picture. CONCLUSION: DAA regimens are safe and effective in patients with HCV-cryoglobulinemia. The achievement of SVR is necessary, but not sufficient, to achieve a complete immunological and clinical response.

Strategic use of dual regimens of boosted protease inhibitors plus maraviroc in poorly adherent subjects in view of long-acting drugs: A retrospective study.

In view of the forthcoming long-acting antiretrovirals, measures should be taken to prevent the selection of HIV drug resistance mutations. All subjects who had been switched to boosted protease inhibitors plus maraviroc (bPIs/MVC) with baseline HIV-1 RNA >50 copies/mL between June, 2014, and April, 2015, were retrospectively evaluated. HIV-1 RNA, CD4+ T-cells, serum glucose, creatinine, ALT, and adverse events were controlled every 3 to 4 months. We retrospectively analyzed 44 patients: 18 were taking darunavir/ritonavir (DRV/r) and 26 atazanavir/ritonavir (ATV/r) once daily, plus MVC 300 mg once daily. Seven subjects were in CDC stage C. All had a follow-up of at least 24 weeks, 28 exceeded 48 weeks, and 21 exceeded 72 weeks. All had experienced at least 1 viral failure and had selected at least 1 resistance-associated mutation (RAM). At baseline, 38 had plasma HIV-1 RNA 50-499 copies/mL and 6 had ≥500. At week 24, none had viremia >500 and 30 (68.2%) had suppressed HIV-1 RNA below 50 copies/mL. Of the subgroup with 48 weeks' follow-up, 23 had HIV-1 RNA 50-499 copies/mL, 5 had ≥500, and 20/28 suppressed to <50 copies/mL. Of the longest observed subgroup (72 weeks), 17 had HIV-1 RNA 50-499 copies/mL, and 4 had ≥500 copies/mL and 15/21 (71.4%) suppressed to <50 copies/mL. This combination allowed fair suppression of viral replication, with minor genotypic evolution in 6 subjects, and seems to be a feasible strategy to prevent damaging future options.

Multiclass HCV resistance to direct-acting antiviral failure in real-life patients advocates for tailored second-line therapies.

BACKGROUND & AIMS: Despite the excellent efficacy of direct-acting antivirals (DAA) reported in clinical trials, virological failures can occur, often associated with the development of resistance-associated substitutions (RASs). This study aimed to characterize the presence of clinically relevant RASs to all classes in real-life DAA failures. METHODS: Of the 200 virological failures that were analyzed in 197 DAA-treated patients, 89 with pegylated-interferon+ribavirin (PegIFN+RBV) and 111 without (HCV-1a/1b/1g/2/3/4=58/83/1/6/24/25; 56.8% treatment experienced; 65.5% cirrhotic) were observed. Sanger sequencing of NS3/NS5A/NS5B was performed by home-made protocols, at failure (N=200) and whenever possible at baseline (N=70). RESULTS: The majority of the virological failures were relapsers (57.0%), 22.5% breakthroughs, 20.5% non-responders. RAS prevalence varied according to IFN/RBV use, DAA class, failure type and HCV genotype/subtype. It was 73.0% in IFN group vs 49.5% in IFN free, with the highest prevalence of NS5A-RASs (96.1%), compared to NS3-RASs (75.9% with IFN, 70.5% without) and NS5B-RASs (66.6% with IFN, 20.4% without, in sofosbuvir failures). In the IFN-free group, RASs were higher in breakthrough/non-responders than in relapsers (90.5% vs 40.0%, P<.001). Interestingly, 57.1% of DAA IFN-free non-responders had a misclassified genotype, and 3/4 sofosbuvir breakthroughs showed the major-RAS-S282T, while RAS-L159F was frequently found in sofosbuvir relapsers (18.2%). Notably, 9.0% of patients showed also extra target RASs, and 47.4% of patients treated with ≥2 DAA classes showed multiclass resistance, including 11/11 NS3+NS5A failures. Furthermore, 20.0% of patients had baseline-RASs, which were always confirmed at failure. CONCLUSIONS: In our failure setting, RAS prevalence was remarkably high in all genes, with a partial exception for NS5B, whose limited resistance is still higher than previously reported. This multiclass resistance advocates for HCV resistance testing at failure, in all three genes for the best second-line therapeutic tailoring.

ITPA and SLC29A1 Genotyping for the Prediction of Ribavirin Dose Reduction in Anti-HCV Triple Therapy with Protease Inhibitors.

Chronic hepatitis C is one of the most important causes of liver disease, leading to cirrhosis, hepatic decompensation and hepatocellular carcinoma. Recently some important advances in therapy have been achieved with the introduction of first wave, first generation direct acting antiviral agents (DAAs) such as boceprevir (BOC), in combination with pegylated interferon (Peg-IFN) and ribavirin (RBV). The superior rate of sustained virological response with this treatment is accompanied by an elevated frequency of anaemia. Several studies have evidenced the importance of single nucleotide polymorphisms (SNPs) in inosine triphosphatase (ITPA) and solute carrier family 29, member 1 (SLC29A1) genes in the development of this adverse event. Here, we investigated haemoglobin levels and the best-known functional SNPs in ITPA and SLC29A1 genes in 22 patients treated with triple therapy with BOC/Peg-IFN/RBV. The identification of ITPA protective and SLC29A1 risk genotypes still appears to be a current methodology in RBV dosing during hepatitis C virus therapy with DAAs.

Metabolic and kidney disorders correlate with high atazanavir concentrations in HIV-infected patients: is it time to revise atazanavir dosages?

INTRODUCTION: Ritonavir-boosted atazanavir (ATV/r) is a relatively well tolerated antiretroviral drug. However, side effects including hyperbilirubinemia, dyslipidemia, nephrolithiasis and cholelithiasis have been reported in the medium and long term. Unboosted ATV may be selected for some patients because it has fewer gastrointestinal adverse effects, less hyperbilirubinemia and less impact on lipid profiles. METHODS: We investigated the distribution of ATV plasma trough concentrations according to drug dosage and the potential relationship between ATV plasma trough concentrations and drug-related adverse events in a consecutive series of 240 HIV-infected patients treated with ATV/r 300/100 mg (68%) or ATV 400 mg (32%). RESULTS: 43.9% of patients treated with ATV/r 300/100 mg had ATV concentrations exceeding the upper therapeutic threshold. A significant and direct association has been observed between the severity of hyperbilirubinemia and ATV plasma trough concentrations (ATV concentrations: 271 [77-555], 548 [206-902], 793 [440-1164], 768 [494-1527] and 1491 [1122-1798] ng/mL in patients with grade 0, 1, 2, 3 and 4 hyperbilirubinemia, respectively). In an exploratory analysis we found that patients with dyslipidemia or nephrolitiasis had ATV concentrations significantly higher (582 [266-1148], and 1098 [631-1238] ng/mL, respectively) (p<0.001), as compared with patients with no ATV-related complications (218 [77-541] ng/mL). CONCLUSIONS: A significant proportion of patients treated with the conventional dosage of ATV (300/100) had plasma concentrations exceeding the upper therapeutic threshold. These patients that are at high risk to experience ATV-related complications may benefit from TDM-driven adjustments in ATV dosage with potential advantages in terms of costs and toxicity.

Hepatitis C virus RNA levels at week-2 of telaprevir/boceprevir administration are predictive of virological outcome.

BACKGROUND: Triple therapy with telaprevir/boceprevir + pegylated-interferon+ribavirin can achieve excellent antiviral efficacy, but it can be burdened with resistance development at failure. AIMS: To evaluate kinetics of hepatitis C virus (HCV) RNA decay and early resistance development, in order to promptly identify patients at highest risk of failure to first generation protease inhibitors. METHODS: HCV-RNA was prospectively quantified in 158 patients receiving pegylated-interferon+ribavirin+telaprevir (N = 114) or+boceprevir (N = 44), at early time-points and during per protocol follow-up. Drug resistance was contextually evaluated by population sequencing. RESULTS: HCV-RNA at week-2 was significantly higher in patients experiencing virological failure to triple-therapy than in patients with sustained viral response (2.3 [1.9-2.8] versus 1.2 [0.3-1.7]log IU/mL, p < 0.001). A 100 IU/mL cut-off value for week-2 HCV-RNA had the highest sensitivity (86%) in predicting virological success. Indeed, 23/23 (100%) patients with undetectable HCV-RNA reached success, versus 26/34 (76.5%) patients with HCV-RNA<100 IU/mL, and only 11/31 (35.5%) with HCV-RNA > 100 IU/mL (p < 0.001). Furthermore, differently from failing patients, none of the patient with undetectable HCV-RNA at week-2 had baseline/early resistance. CONCLUSIONS: With triple therapy based on first generation protease inhibitors, suboptimal HCV-RNA decay at week-2 combined with early detection of resistance can help identifying patients with higher risk of virological failure, thus requiring a closer monitoring during therapy.

Comparison of the pharmacokinetics of raltegravir given at 2 doses of 400 mg by swallowing versus one dose of 800 mg by chewing in healthy volunteers: a randomized, open-label, 2-period, single-dose, crossover phase 1 study.

BACKGROUND: The pharmacokinetics of raltegravir (RAL) in HIV patients is characterized by high interindividual and intraindividual variability. We documented previously that HIV patients taking RAL at 400 mg bid by chewing the tablets had significantly higher drug absorption and reduced pharmacokinetic variability than patients taking the drug by swallowing the tablets. This study extends our previous findings. METHODS: An open-label, 2-period crossover study compared the pharmacokinetics of 2 doses of RAL given at 400 mg every 12 hours (that mimics a bid administration) by swallowing with 1 dose of 800 mg (that mimics a qd administration) by chewing the tablets in 12 healthy volunteers. RAL plasma concentrations were measured by a chromatographic method coupled with mass spectrometry. RESULTS: Subjects taking RAL by chewing had significantly higher drug exposure (RAL area under the curve[AUC](0-24): 40722 ± 14843 versus 21753 ± 12229 ng · h/mL, P < 0.0001) and reduced pharmacokinetic variability compared with those taking the drug by swallowing the whole tablet, with no difference in the minimum RAL concentrations (RAL C(min): 36 ± 23 versus 43 ± 23 ng/mL, P = 0.298). Subjects taking RAL by chewing the tablets had significantly higher drug absorption and reduced pharmacokinetic variability compared with those taking the drug by swallowing. No differences were observed in the minimum RAL concentrations. CONCLUSIONS: RAL at 800 mg once daily by chewing the tablets may represent a novel therapeutic option for the treatment of HIV being associated with higher drug absorption, reduced pharmacokinetic variability, and potentially better compliance compared with patients swallowing the 400-mg bid intact tablets.

Four years data of raltegravir-based salvage therapy in HIV-1-infected, treatment-experienced patients: the SALIR-E Study.

Apart from the BENCHMRK study, there are no large observational experiences describing the long-term efficacy and safety of rescue regimens for human immunodeficiency virus type 1 (HIV-1) infection. Antiretroviral-experienced patients with detectable viraemia starting a raltegravir (RAL)-based regimen between March 2007 and June 2009 were consecutively enrolled and followed for ≥4 years. Data were censored at Week 206 for homogeneity. Of 333 patients, 258 (77.5%) were still on RAL-based therapy at Week 206, and 241 had undetectable HIV-1 RNA (73% in intention-to-treat analysis). Of the 75 subjects who discontinued RAL therapy, 36 were lost to follow-up, 15 changed their regimen due to virological failure, 2 simplified their regimen stopping RAL, 9 stopped all antiretrovirals and 13 died. Overall, 100 subjects (30.0%) had at least one detectable viraemia, but only 32 (9.6%) had true viral failure. Seventeen patients continued their failing regimen. 'Blips' were experienced by 53 patients (15.9%), whilst 15 (4.5%) had confirmed viral rebound due to adherence issues and were re-suppressed upon treatment re-introduction. In a multivariate analysis of predictors of interruption or failure, each baseline HIV-1 RNA log10 increase was associated with an adjusted hazard ratio for failure of 1.6; having more than 13 previous treatment courses also emerged as a predictor. Overall, adverse events were rare (n=64), with 13 deaths. Tumours were mainly early events, often fatal (7/15), mainly non-Hodgkin's lymphomas (8), followed by hepatocarcinoma (2). RAL proved effective and well tolerated in this cohort, and few patients experienced viral failure after 4 years.

Low body weight in females is a risk factor for increased tenofovir exposure and drug-related adverse events.

Treatment with tenofovir sometimes leads to non-reversible kidney and/or bone diseases. Factors associated with these drug-related adverse events are poorly characterized. Our objective was to investigate such factors in patients treated long term with daily tenofovir. One-hundred Caucasian HIV-positive patients with basal creatinine clearance >80 mL/min treated with tenofovir for at least 6 months and with at least one assessment of tenofovir plasma trough concentrations were considered. Tenofovir-associated adverse events were defined as the appearance of pathological proteinuria, worsening of renal function or bone demineralization. By multivariate regression analysis, we found that serum creatinine (p = 0.003) and body weight (p = 0.002) were the factors independently associated with plasma tenofovir concentrations. In particular, women with body weight<50 kg had significantly higher plasma tenofovir concentrations than those weighting >50 Kg (160±93 vs.71±52 ng/mL, p<0.001). High tenofovir plasma trough concentrations and the age of the patients were independently associated with the development of drug-related kidney and bone toxicity. In this retrospective study we have shown that HIV-infected women with low body weight are at risk to be exposed to high tenofovir plasma trough concentrations, ultimately resulting in a significant hazard to develop long-term tenofovir complications.

A boceprevir failure in a patient infected with HCV genotype 1g: importance and limitations of virus genotyping prior to HCV protease-inhibitor-based therapy.

A patient classified as HCV-1a-positive by both LiPA Siemens 2.0 and Abbott RealTime HCV Genotype II was instead found to be infected with HCV-1g, as determined by phylogenetic analysis of NS3 sequences. HCV-1g NS3 sequences available to date naturally harbour the resistance substitution T54S, plus P131S and L135F changes, located in the highly conserved NS3 positions within the boceprevir-binding site, as determined by structural modelling. HCV-1g NS3 sequences show some similarities to HCV-4 and are poorly responsive to interferon/ribavirin and to boceprevir/telaprevir; this patient was also a null-responder to boceprevir treatment. Baseline genotypic resistance testing may provide crucial information for the management of first-generation protease-inhibitor-based regimens, including both HCV genotype/subtype and natural resistance.

Comparison of the in vivo pharmacokinetics and in vitro dissolution of raltegravir in HIV patients receiving the drug by swallowing or by chewing.

The pharmacokinetics of raltegravir (RAL) in HIV patients is characterized by high interpatient/intrapatient variability. We investigated the potential contribution of the drug pharmaceutical formulation to RAL pharmacokinetics. We first compared in vivo the pharmacokinetics of RAL for 67 patients to whom the drug was administered by swallowing the intact tablet with those obtained from 13 HIV-infected patients who chewed the RAL tablet due to swallowing difficulties. Subsequently, we evaluated in vitro the dissolution of RAL tablets under different conditions. In the in vivo study, we found that patients given RAL by chewing the tablets presented pharmacokinetic profiles characterized by significantly higher RAL absorption than did patients receiving the drug by swallowing. The in vitro studies showed that when the whole tablets were exposed to an acidic medium, the release of RAL was very low, whereas when the tablets were crushed, the profiles presented significantly higher concentrations of RAL. Crushed tablets tested in water or in a pH 6.8 buffer exhibited prompt and complete dissolution of RAL. HIV-infected patients receiving RAL by chewing the tablet showed higher drug absorption and reduced pharmacokinetic variability compared with patients swallowing the intact tablet. This is related to problems in tablet disintegration and to erratic drug absorption. The amelioration of the RAL pharmaceutical formulation could improve drug pharmacokinetics.

96 Week follow-up of HIV-infected patients in rescue with raltegravir plus optimized backbone regimens: a multicentre Italian experience.

BACKGROUND: Long term efficacy of raltegravir (RAL)-including regimens in highly pre-treated HIV-1-infected patients has been demonstrated in registration trials. However, few studies have assessed durability in routine clinical settings. METHODS: Antiretroviral treatment-experienced patients initiating a RAL-containing salvage regimen were enrolled. Routine clinical and laboratory follow-up was performed at baseline, week 4, 12, and every 12 weeks thereafter. Data were censored at week 96. RESULTS: Out of 320 patients enrolled, 292 (91.25%) subjects maintained their initial regimen for 96 weeks; 28 discontinued prematurely for various reasons: death (11), viral failure (8), adverse events (5), loss to follow-up (3), consent withdrawal (1). Eight among these 28 subjects maintained RAL but changed the accompanying drugs. The mean CD4+ T-cell increase at week 96 was 227/mm(3); 273 out of 300 patients (91%), who were still receiving RAL at week 96, achieved viral suppression (HIV-1 RNA <50 copies/mL). When analyzing the immuno-virologic outcome according to the number of drugs used in the regimen, 2 (n = 45), 3 (n = 111), 4 (n = 124), or >4 (n = 40), CD4+ T-cell gain was similar across strata: +270, +214, +216, and +240 cells/mm(3), respectively, as was the proportion of subjects with undetectable viral load. Laboratory abnormalities (elevation of liver enzymes, total cholesterol and triglycerides) were rare, ranging from 0.9 to 3.1%. The mean 96-week total cholesterol increase was 23.6 mg/dL. CONCLUSIONS: In a routine clinical setting, a RAL-based regimen allowed most patients in salvage therapy to achieve optimal viral suppression for at least 96 weeks, with relevant immunologic gain and very few adverse events.

Co-administration of raltegravir reduces daily darunavir exposure in HIV-1 infected patients.

The potential drug-to-drug interaction between darunavir and raltegravir in the setting of HIV infection is a highly debated issue still unresolved. In the present study we have evaluated the pharmacokinetics of darunavir and ritonavir in 53 HIV-1 infected patients with or without concomitant raltegravir administration. The assessment of trough plasma drug concentrations was carried out in all subjects and the potential influence of raltegravir on darunavir and ritonavir disposition, assessed by specific pharmacokinetic evaluations in a subgroup of 25 patients. No significant differences on darunavir and ritonavir plasma trough levels were observed between patients receiving or not raltegravir. Co-administration of raltegravir was, however, associated with a 40% reduction in darunavir C(max) and estimated AUC(0-24), as well a 60% increase in the estimated darunavir clearance compared with values measured in patients not given raltegravir. Notably, this interaction was independent of the dosage of darunavir and not due to effects of raltegravir on the pharmacokinetics of ritonavir. These results should be taken into account when darunavir-based regimens are implemented in the setting of HIV, especially considering that this drug is usually administered at fixed daily dose and no therapeutic drug monitoring is performed in most centres.

Limited sampling strategies for the estimation of raltegravir daily exposure in HIV-infected patients.

Stepwise multiple regression analyses were applied to 50 raltegravir pharmacokinetic profiles from 50 HIV patients with the goal to identify limited sampling strategies for the prediction of drug area under the time-concentration curve (AUC(0-12)). Raltegravir single sampling point-based equations failed to reliably predict daily drug exposure. Conversely, different algorithms based on few samples and associated with good correlation, acceptable bias, and imprecision with the measured raltegravir AUC(0-12) were identified. These models could used to predict raltegravir exposure for clinic or research purposes.