Sex-related difference analyses of efficacy and safety in clinical trials of direct-acting antivirals to treat chronic HCV genotype 1 and 3 infections.

This study aims to identify clinically meaningful sex differences in efficacy and selected safety adverse events for the treatment of chronic hepatitis C virus infection (HCV) or HIV/HCV co-infection in those receiving combination direct-acting antiviral (DAA) regimens. Our assessment was based on adult trial participants treated at the approved DAA dosage and treatment duration from 40 phase 3 clinical trials submitted to the FDA. Female enrollment ranged from 11% to 54% (overall mean 38%). Females with HCV genotype (GT) 1 or 3 infection had statistically significant higher unadjusted or covariant-adjusted odds of achieving sustained virologic response at post-treatment Week 12 (SVR12) compared with males. Odds ratios favouring females were observed among Whites and those ≥40 years of age with HCV GT1 or 3 infections, and among those ≥50 years of age, non-cirrhotic and those with HCV GT3 infection who were treatment-experienced. These differences were not clinically relevant due to the high SVR12 rate achieved by females and males, overall or in subgroups. No differences were observed in SVR12 rates between HCV GT1 mono-infected and HCV GT1/ HIV-1 co-infected participants. Numerically, more females reported headache, fatigue and nausea compared to males, but the differences were small and predominately Grade 1 or 2 severity. Discontinuation rates for any reason or due to an adverse event were low and similar between the sexes. Our study demonstrated females successfully complete DAA regimens and achieve high SVR12 rates despite numerically higher adverse events for certain commonly reported events.

Long-Acting Formulations for the Prevention and Treatment of Human Immunodeficiency Virus (HIV)-1 Infection: Strategic Leveraging and Integration of Multidisciplinary Knowledge to Advance Public Health.

The landscape for the development of therapeutics for prevention and treatment of human immunodeficiency virus (HIV)-1 infection has pivoted towards long-acting antiretrovirals (LA-ARVs). LA-ARVs have the potential to transform global implementation of HIV-1 prevention and treatment strategies. The ability to identify potential knowledge gaps early in development, proactively address missing information or data gaps, and strategically leverage all the available information is the key to streamline the development of safe and effective LA-ARV therapeutics. The purpose of this article is to discuss some potential considerations for development of LA-ARVs. Three possible drug development scenarios are briefly discussed and include developing (1) a novel LA-ARV, (2) a novel LA formulation of an approved oral ARV, and (3) an LA pro-drug of an approved oral ARV. For each of these scenarios, we briefly describe what type(s) of information may be helpful and discuss potential opportunities to leverage available information. Additionally, we discuss some unique LA-ARV drug development considerations, including the use of an oral lead-in, and assessing the impact of residual ARV exposures on subsequent regimens and evaluation of LA-ARVs in specific populations. We strongly believe that efficient integration of multidisciplinary knowledge can advance the development, availability, and accessibility of therapeutics not only for HIV-1 prevention and treatment but also for other chronic viral infections.

Benefit-risk assessment for sofosbuvir/velpatasvir/voxilaprevir based on patient population and hepatitis C virus genotype: U. S. Food and Drug Administration's evaluation.

On July 18, 2017, the U.S. Food and Drug Administration (FDA) approved sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) (Vosevi) fixed-dose combination (FDC), an interferon-free, complete regimen for adult patients with chronic hepatitis C virus (HCV) infection without cirrhosis or with compensated cirrhosis (Child-Pugh A) who have: • genotype 1, 2, 3, 4, 5, or 6 infection and have previously been treated with an HCV regimen containing a nonstructural protein 5A (NS5A) inhibitor; and • genotype 1a or 3 infection and have previously been treated with an HCV regimen containing sofosbuvir without an NS5A inhibitor. Approval was based on an acceptable safety profile and high sustained virological response rates 12 weeks after the end of treatment (SVR12) in two phase 3 clinical trials in subjects previously treated with a direct-acting antiviral (DAA) regimen. In POLARIS-1, 96% of SOF/VEL/VOX-treated subjects achieved SVR12. In POLARIS-4, 98% of SOF/VEL/VOX-treated subjects achieved SVR12. A key and challenging question in evaluating the data was determining the contribution of VOX to SOF/VEL and how this differed depending on the genotype and patient population. In this article, we provide our perspective on the issues considered in making these determinations, especially regarding the POLARIS-4 data in subjects who have previously been treated with a chronic HCV regimen containing sofosbuvir without an NS5A inhibitor. Conclusion: We seek to provide context as to why a broad indication was given for NS5A inhibitor-experienced patients (HCV genotypes 1-6) while the indication for NS5A inhibitor- naïve patients was limited to HCV genotypes 1a and 3 only. (Hepatology 2018;67:482-491).

Why did the FDA approve efavirenz 800 mg when co-administered with rifampin?

OBJECTIVES: Literature reports regarding the efficacy of efavirenz (EFV) 600 mg with rifampin (RIF) are not consistent. Evaluation of a drug-drug interaction (DDI) study and supportive semi-mechanistic population pharmacokinetic (PK) analyses were undertaken to help delineate this issue. DESIGN/METHODS: DDI study and supportive semi-mechanistic population PK analyses were provided by BMS. Population PK analysis was based on six studies with intensive EFV PK sampling. An ACTG study with sparse PK sampling was used for model evaluation. Simulations compared EFV exposure at various doses in combination with RIF to EFV exposures at 600 mg once daily (QD). Effects of CYP2B6 genotypes on the magnitude of EFV-RIF interaction were also explored. RESULTS: In DDI study, co-administering EFV 600 mg QD and RIF reduced mean EFV exposure by ~ 30%. Population PK model provided acceptable predictive performance of central tendency and variability for EFV C0, Cmax, and AUC. Simulations predicted that increasing EFV to 800 mg QD with RIF would result in EFV AUC and Cmax similar to EFV 600 mg QD alone. EFV AUC and Cmax were ~ 2 times higher in subjects with reduced function CYP2B6 genotypes. However, the RIF effect was consistent across all genotypes. EFV dose adjustment to 800 mg QD did not increase the risk of overexposure compared to 600 mg EFV QD within each genotype. CONCLUSION: Dose adjustment based on matching systemic exposure was recommended to mitigate the potential for sub-therapeutic EFV exposures. Our review did not reveal any safety concerns in subjects receiving EFV 800 mg QD with RIF.

Pharmacokinetics of Antiretroviral Agents in Pregnant Individuals Living With HIV: Current Status and Considerations for Study Design and Interpretation.

Determining the appropriate dosing regimens of antiretroviral (ARV) drugs for pregnant individuals living with HIV-1 infection is critical to maximize maternal health and prevent perinatal HIV transmission. Throughout pregnancy, pharmacokinetics (PK) of ARVs can be significantly altered due to physiological, anatomic, and metabolic changes. As such, conducting PK studies of ARVs during pregnancy is crucial to optimize dosing regimens. In this article, we summarize available data, key issues, challenges, and considerations in interpreting results of ARV PK studies in pregnant individuals. Discussion topics include the choice of the reference population (postpartum vs historical control), pregnancy trimester-dependent changes in ARV PK, effects of pregnancy on once- versus twice-daily dosing, factors to consider for ARVs that are administered with a PK booster such as ritonavir and cobicistat, and considerations when evaluating the effects of pregnancy on unbound ARV concentrations. Common approaches for the translation of the results into clinical recommendations and rationales and considerations when making clinical recommendations are summarized. Currently, limited PK data in pregnancy are available with long-acting ARVs. Collection of PK data to characterize the PK profile of long-acting ARVs is an important goal shared by many stakeholders.

Participation of HIV-1 infected treatment-naive females in clinical trials and sex differences in efficacy and safety outcomes.

OBJECTIVES: To examine female participation and the observed efficacy and safety by sex from phase 3 HIV-1 trials submitted to the United States Food and Drug Administration (FDA) to support approval or a major labeling change. DESIGN: Our analyses were based on phase 3 trials in HIV-1 infected treatment-naive adults submitted to FDA since 2010. METHODS: We evaluated enrollment of treatment-naive females in 18 clinical trials for HIV-1. Participation to prevalence ratio (PPR) was calculated as the percentage of females among trial participants divided by the percentage of females in the disease population. PPR between 0.8 and 1.2 reflects similar representation of females in the trial and the disease population. Sex differences in efficacy (virologic response rates) and selected safety events were evaluated. RESULTS: United States (US) females, particularly US Black females were not adequately represented in clinical trials. The PPR for US females overall was 0.59 and for US Black females was 0.63. Statistically significant sex differences favoring males were observed for efficacy outcomes in both the global population and US participants. Statistically significant sex differences were observed for some safety outcomes. CONCLUSIONS: US females are underrepresented in phase 3 HIV-1 clinical trials. Underrepresentation was not likely due to enrollment criteria. Statistically significant sex differences were noted for efficacy and selected safety outcomes; however, some differences were not clinically relevant. The ability to detect sex differences was hindered by low numbers of female participants overall and within subgroups. Additional research into innovative approaches to recruit and retain females in clinical trials should continue.

Considerations and Challenges in the Remdesivir COVID-19 Pediatric Development Program.

The US Food and Drug Administration is committed to the development of effective antiviral regimens for pediatric patients with coronavirus disease 2019 (COVID-19), including infants and neonates. On April 25, 2022, the approved indication of remdesivir (RDV) was expanded to include pediatric patients 28 days and older and weighing at least 3 kg with positive results of direct severe acute respiratory syndrome coronavirus 2 viral testing, who are: Hospitalized, or Not hospitalized and have mild to moderate COVID-19 and are at high risk for progression to severe COVID-19, including hospitalization or death. Given the similar course of COVID-19 in adults and pediatric patients, the approval of RDV for use in pediatric patients is supported by the safety and efficacy data from adequate and well-controlled phase 3 trials in adults and adolescents; and by the safety and pharmacokinetic data from a single-arm, open-label, phase 2/3 pediatric clinical trial of 53 pediatric patients at least 28 days of age and weighing at least 3 kg with confirmed severe acute respiratory syndrome coronavirus 2 infection and mild, moderate, or severe COVID-19. At the time of the April 25, 2022, approval action, the US Food and Drug Administration also revoked the emergency use authorization for RDV that previously covered this pediatric population. This article summarizes key issues and regulatory considerations involved in the RDV COVID-19 pediatric development program, including the evolution of the emergency use authorization issued for RDV as results from registrational studies became available, and discusses lessons learned.

Emergency use authorization for intravenous peramivir: evaluation of safety in the treatment of hospitalized patients infected with 2009 H1N1 influenza A virus.

BACKGROUND: On 23 October 2009, the US Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for intravenous peramivir, an unapproved antiviral, to treat suspected or confirmed 2009 H1N1 influenza A virus infection. Eligible hospitalized patients were unresponsive to or unable to tolerate available antivirals or lacked dependable oral or inhaled drug delivery routes. The EUA required healthcare providers to report medication errors, selected adverse events (AEs), serious AEs, and deaths to the FDA. METHODS: An FDA safety team analyzed reports submitted to the Adverse Event Reporting System (AERS) and sought follow-up in selected cases. RESULTS: The FDA received AERS reports for 344 patients (including 28 children and 3 pregnant women). Many patients were critically ill on mechanical ventilation (41%) and renal replacement therapies (19%); 38% had received oseltamivir. The most frequently reported serious AEs by MedDRA preferred term were death (15%), H1N1 influenza (8%), respiratory failure (8%), acute renal failure (7%), and acute respiratory distress syndrome (7%). Six medication errors were reported. Most deaths occurred among patients who were obese, immunosuppressed, aged >65 years, or received oseltamivir. Rash was the only treatment-emergent AE attributable to peramivir. Influenza severity, comorbidities, and concomitant medications confounded additional peramivir AE assessments. Missing clinical and laboratory data precluded evaluation of some reports. CONCLUSIONS: Many peramivir recipients under the EUA were critically ill and at risk for influenza-related complications. The safety data were insufficient to assess whether peramivir affected outcome or caused adverse reactions other than rash. Clinical trials in hospitalized patients with serious influenza infections should provide additional information.

Characterization of Plasma Protein Alterations in Pregnant and Postpartum Individuals Living With HIV to Support Physiologically-Based Pharmacokinetic Model Development.

Background: Alterations in plasma protein concentrations in pregnant and postpartum individuals can influence antiretroviral (ARV) pharmacokinetics. Physiologically-based pharmacokinetic (PBPK) models can serve to inform drug dosing decisions in understudied populations. However, development of such models requires quantitative physiological information (e.g., changes in plasma protein concentration) from the population of interest. Objective: To quantitatively describe the time-course of albumin and α1-acid glycoprotein (AAG) concentrations in pregnant and postpartum women living with HIV. Methods: Serum and plasma protein concentrations procured from the International Maternal Pediatric Adolescent AIDS Clinical Trial Protocol 1026s (P1026s) were analyzed using a generalized additive modeling approach. Separate non-parametric smoothing splines were fit to albumin and AAG concentrations as functions of gestational age or postpartum duration. Results: The analysis included 871 and 757 serum albumin concentrations collected from 380 pregnant (~20 to 42 wks gestation) and 354 postpartum (0 to 46 wks postpartum) women, respectively. Thirty-six and 32 plasma AAG concentrations from 31 pregnant (~24 to 38 wks gestation) and 30 postpartum women (~2-13 wks postpartum), respectively, were available for analysis. Estimated mean albumin concentrations remained stable from 20 wks gestation to term (33.4 to 34.3 g/L); whereas, concentrations rapidly increased postpartum until stabilizing at ~42.3 g/L 15 wk after delivery. Estimated AAG concentrations slightly decreased from 24 wks gestation to term (53.6 and 44.9 mg/dL) while postpartum levels were elevated at two wks after delivery (126.1 mg/dL) and subsequently declined thereafter. Computational functions were developed to quantitatively communicate study results in a form that can be readily utilized for PBPK model development. Conclusion: By characterizing the trajectory of plasma protein concentrations in pregnant and postpartum women living with HIV, our analysis can increase confidence in PBPK model predictions for HIV antiretrovirals and better inform drug dosing decisions in this understudied population.

Benefit-risk assessment for brincidofovir for the treatment of smallpox: U.S. Food and Drug Administration's Evaluation.

The development and approval of brincidofovir for the treatment of smallpox, a disease that was eradicated from the world over 40 years ago, has resulted in the second antiviral approved via the Medical Countermeasure Initiative (MCMi) to combat this disease. Approval of brincidofovir required a unique regulatory approach based on the FDA Animal Rule, and development was supported by many years of research and collaboration among academic investigators, the pharmaceutical industry and multiple government agencies. This article summarizes the FDA regulatory pathway and describes the challenges involved.

Optimizing Pharmacology Studies in Pregnant and Lactating Women Using Lessons From HIV: A Consensus Statement.

Information on the extent of drug exposure to mothers and infants during pregnancy and lactation normally becomes available years after regulatory approval of a drug. Clinicians face knowledge gaps on drug selection and dosing in pregnancy and infant exposure during breastfeeding. Physiological changes during pregnancy often result in lower drug exposures of antiretrovirals, and in some cases a risk of reduced virologic efficacy. The International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) network and the World Health Organization (WHO)-convened Pediatric Antiretrovirals Working Group collaboratively organized a workshop of key stakeholders in June 2019 to define key standards to generate pharmacology data for antiretrovirals to be used among pregnant and lactating women; review the antiretroviral product pipeline; describe key gaps for use in low-income and middle-income countries; and identify opportunities to undertake optimal studies allowing for rapid implementation in the clinical field. We discussed ethical and regulatory principles, systemic approaches to obtaining data for pregnancy pharmacokinetic/pharmacodynamic (PK/PD) studies, control groups, optimal sampling times during pregnancy, and pharmacokinetic parameters to be considered as primary end points in pregnancy PK/PD studies. For lactation studies, the type of milk to collect, ascertainment of maternal adherence, and optimal PK methods to estimate exposure were discussed. Participants strongly recommended completion of preclinical reproductive toxicology studies prior to phase III, to allow study protocols to include pregnant women or to allow women who become pregnant after enrolment to continue in the trial. The meeting concluded by developing an algorithm for design and interpretation of results and noted that recruitment of pregnant and lactating women into clinical trials is critical.

Considerations and challenges in developing novel long-acting antiretrovirals modalities for treatment and prevention of HIV-1 infection: a regulatory perspective.

PURPOSE OF REVIEW: Outline some regulatory considerations and scientific challenges related to the development of long-acting antiretrovirals (ARVs) for the treatment and prevention of HIV-1 infection. RECENT FINDINGS: Poor adherence to oral ARV regimens continues to pose challenges for effective treatment and prevention of HIV-1 infection. The development of long-acting ARV modalities for treatment and prevention of HIV-1 infection is emerging as a promising alternative to the current treatment and prevention paradigm and has gained considerable interest. SUMMARY: The development of long-acting ARVs can present some unique drug development challenges. Advance planning and prioritization of studies early in development can facilitate the development of long-acting ARVs for the prevention and treatment of HIV-1 infection for all populations, including pediatric patients and pregnant women.

Cobicistat-containing antiretroviral regimens are not recommended during pregnancy: viewpoint.

: Product labels for cobicistat with atazanavir or darunavir, and for elvitegravir/cobicistat/emtricitabine/tenofovir (alafenamide or disoproxil fumarate) were recently updated to state that these products are not recommended for initiation during pregnancy, and an alternative regimen is recommended for those who become pregnant during therapy with these products. Herein, we present the rationale for these recommendations, which are based on studies in pregnant women evaluating the pharmacokinetics and antiviral activity of darunavir/cobicistat or elvitegravir/cobicistat-containing antiretroviral regimens. In these studies, mean steady-state minimum concentrations in the second and third trimester versus postpartum of cobicistat, darunavir, and elvitegravir were reduced by 61-83%, 89-92%, and 82-86%, respectively. In the absence of data with atazanavir/cobicistat, we leveraged the available data with darunavir/cobicistat and elvitegravir/cobicistat to make recommendations for atazanavir/cobicistat. Darunavir/ritonavir and atazanavir/ritonavir remain viable treatment options for pregnant women.

Sustained virological response rates with direct-acting antivirals in black subjects with HCV genotype 1 infection: systematic analysis of clinical trials.

OBJECTIVES: Under representation of black subjects in trials of hepatitis C virus (HCV) direct-acting antivirals (DAAs) complicates assessment of differential outcomes for black individuals vs non-black individuals. HCV trials submitted to the Food and Drug Administration (2013-2017) to support approval or to expand an indication of 12-week interferon-free DAA regimens with or without ribavirin to treat HCV genotype 1 (GT1) infection were pooled to explore efficacy comparisons by ethnicity. METHODS: Twenty-six trials were pooled and included 2869 individuals with HCV GT1 alone and 742 individuals with both HCV GT1 and HIV. RESULTS: Of the 2869 HCV GT1-mono-infected subjects, 408 (14.2%) were black. Sustained virological response assessed 12 weeks following cessation of treatment (SVR12) was 92%-100% in black individuals and 87.5%-100.0% in non-black individuals. In pooled analyses, SVR12 was numerically similar between black and non-black subjects (97.1% vs 97.3%). Baseline characteristics did not affect SVR12 for the two groups. Of the 742 subjects with both HCV GT1 and HIV, 243 (32.7%) were black: SVR12 was 89.5%-100% in black individuals and 94.4%-100% in non-black individuals. In pooled analyses for HCV GT1/HIV co-infection, black individuals had a 4% (95% confidence interval -7.7% to 0.3%) lower SVR12 than non-black individuals (93.4% vs 97.0%). This difference was driven by ION-4 in which study SVR12 was approximately 10% lower for black than for non-black individuals (89.5% vs 99.1%). Baseline characteristics did not affect SVR12 for the two groups. CONCLUSION: No notable SVR12 differences were seen in between black and non-black individuals with HCV GT1 alone. Although a numerical difference was observed between black and non-black individuals with both HCV GT1 and HIV, this finding was driven by results from a single trial and may be due to reasons other than ethnicity: 19 subgroup analyses showed baseline characteristics did not affect SVR12 for black and non-black individuals with both HCV GT1 and HIV.

Long-acting or extended-release antiretroviral products for HIV treatment and prevention in infants, children, adolescents, and pregnant and breastfeeding women: knowledge gaps and research priorities.

Antiretroviral agents with long-acting properties have potential to improve treatment outcomes substantially for people living with HIV. In November 2017, the Long acting/Extended Release Antiretroviral Resource Program (LEAP) convened a workshop with the aim of shaping the research agenda and promoting early development of long-acting or extended release products for key populations: pregnant and lactating women, children aged up to 10 years, and adolescents aged 10-19 years. Goals included strategies and principles to ensure that the needs of children, adolescents, and pregnant and lactating women are considered when developing long-acting formulations. Research should focus not only on how best to transition long-acting products to these populations, but also on early engagement across sectors and among stakeholders. A parallel rather than sequential approach is needed when establishing adult, adolescent, and paediatric clinical trials and seeking regulatory approval. Pregnant and lactating women should be included in adult clinical trials. Adolescent-friendly trial design is needed to improve recruitment and retention of young people.

Are literature references sufficient for dose recommendations? An FDA case study of efavirenz and rifampin.

One of the numerous regulatory functions of the Food and Drug Administration (FDA) is the evaluation of drug-drug interactions and the determination of appropriate dose adjustments, if necessary, to ensure the safe and effective use of medications. The FDA considers several data sources when determining the significance of drug-drug interactions. The majority of dose adjustment recommendations are based on specific drug-drug interactions studies. The FDA reviews individual patient pharmacokinetic and safety data from drug interaction studies, determines appropriate dose adjustments, and provides recommendations to update the respective product labeling. Sometimes literature references are submitted to the FDA to support dosing recommendations. Determining an appropriate dose adjustment recommendation based on literature reports is a challenge for the FDA due to the lack of individual patient pharmacokinetic or safety data from these studies. Recently, the FDA encountered a challenging regulatory situation when evaluating literature reports to determine the appropriate dose of efavirenz and rifampin. Although numerous studies were found in the literature about this combination, a dosing recommendation cannot be concluded from the reported data. This article reviews the process the FDA used to evaluate literature to support potential dose adjustments for efavirenz when coadministered with rifampin and the challenges encountered during the process.

Age Differences by Sex in Antiretroviral-Naïve Participants: Pooled Analysis from Randomized Clinical Trials.

Age and sex effects on antiretroviral therapy (ART) response are not well elucidated. Our pooled analysis of 40 randomized clinical trials measured the association of age and sex on CD4+ T cell count changes and virologic suppression using multivariable regression modeling. The average increase in CD4+ T cell count from baseline to week 48 was 17.3 cells/mm3 lower and clinically insignificant (95% confidence interval -30.8 to -3.8) among women ages ≥ 50 years (n = 573), compared to women ≤ 35 years (n = 3,939). Results were similar for men. Virologic suppression odds were 60% and 21% times greater among participants ≥50 years compared to ≤35 years, in women and men, respectively. In both sexes, larger increases in CD4+ T cell count changes were observed in younger, compared to older, participants; however, virologic suppression was higher in older, compared to younger, participants suggesting a non-sex-specific age effect response to ART.

Food and Drug Administration analysis of tipranavir clinical resistance in HIV-1-infected treatment-experienced patients.

OBJECTIVE: To assess the resistance profile of tipranavir. METHODS: Resistance analyses were performed on Boëhringer Ingelheim-sponsored studies examining the safety and efficacy of tipranavir in highly treatment-experienced individuals at 24 weeks. Virologic response rates based on the presence of baseline primary protease inhibitor mutations and based on baseline tipranavir susceptibility were evaluated, and the development of protease mutations during treatment with tipranavir was analyzed. RESULTS: Virologic response rates in tipranavir-treated individuals were reduced when isolates with substitutions at amino acid positions I13, V32, M36, I47, Q58, D60 V82 or I84 were present at baseline. In addition, virologic response rates to tipranavir decreased when the number of baseline protease inhibitor (PI) mutations was five or more. Individuals who received tipranavir without concomitant enfurvitide and had five or more baseline PI mutations group began to lose antiviral response between weeks 4 and 8. However, individuals taking enfuvirtide with tipranavir were able to achieve greater than 1.5 log10 reductions in viral load from baseline out to 24 weeks even if they had five or more baseline PI mutations. Virologic response rates to tipranavir decreased when the baseline phenotype for tipranavir had a greater than three-fold shift in the 50% effective concentration (EC50) from reference. The most common protease mutations that developed in tipranavir-treated individuals who experienced virologic failure were L10I/V/S, I13V, L33V/I/F, M36V/I/L V82T, V82L, and I84V. The resistance profile in treatment-naive individuals was not characterized. CONCLUSIONS: Baseline genotypic and phenotypic data provide valuable information on the likelihood of a virologic response to tipranavir.

Atazanavir-associated nephrolithiasis: cases from the US Food and Drug Administration's Adverse Event Reporting System.

The risk of nephrolithiasis associated with atazanavir is not well characterized. The US Food and Drug Administration's Adverse Event Reporting System was searched for reports of nephrolithiasis in HIV-infected patients taking an atazanavir-based regimen. Thirty cases were identified. Many patients required hospitalization for management, including lithotripsy, ureteral stent insertion, or endoscopic stone removal. Some cases of nephrolithiasis resulted in atazanavir discontinuation. Healthcare professionals and patients should be informed that nephrolithiasis is a possible adverse event with atazanavir.

Reinventing HCV Treatment: Past and Future Perspectives.

This review paper summarizes the epidemiology of hepatitis C virus (HCV) and chronic HCV infection, including HCV virology and treatment regimens. Specifically, we focus on the evolution of past, current, and future HCV treatment options, the reasons for treatment failure, and the impact of resistance-associated variants on treatment success.