Background GNE myopathy is a rare genetic muscle disease resulting from deficiency in an enzyme critical for the biosynthesis of N -acetylneuraminic acid (Neu5Ac, sialic acid). The uncharged Neu5Ac precursor, N -acetylmannosamine (ManNAc), is under development as an orphan drug for treating GNE myopathy. Methods A semi-mechanistic population pharmacokinetic model was developed to simultaneously characterize plasma ManNAc and its metabolite Neu5Ac following oral administration of ManNAc to subjects with GNE myopathy. Plasma ManNAc and Neu5Ac pharmacokinetic data were obtained from two clinical studies (ClinicalTrials.gov identifiers NCT01634750, NCT02346461) and were simultaneously modeled using NONMEM. Results ManNAc and Neu5Ac plasma concentrations were obtained from 34 subjects with GNE myopathy (16 male, 18 female, median age 39.5 years). The model parameter estimates included oral absorption rate ( k a ) = 0.256 h −1 , relative bioavailability relationship with dose (F-Dose) slope = −0.405 (where F = 1 for 6-g dose), apparent clearance (CL M / F ) = 631 L/h, volume of distribution ( V M / F ) = 506 L, Neu5Ac elimination rate constant ( k out ) = 0.283 h −1 , initial ManNAc to Neu5Ac conversion (SLP 0 ) = 0.000619 (ng/mL) −1 and at steady-state (SLP SS ) = 0.00334 (ng/mL) −1 , with a rate-constant of increase ( k inc ) = 0.0287 h −1 . Goodness-of-fit plots demonstrated an acceptable and unbiased fit to the plasma ManNAc and Neu5Ac concentration data. Visual predictive checks demonstrated reasonable agreement between the 5th, 50th, and 95th percentiles of the observed and simulated data. Conclusions This population pharmacokinetic model can be used to evaluate ManNAc dosing regimens and to calculate Neu5Ac production and exposure following oral administration of ManNAc in subjects with GNE myopathy. Supplementary Information The online version contains supplementary material available at 10.1007/s40268-021-00343-6.

Objectives Efavirenz is currently suggested as an alternative to recommended antiretroviral (ARV) regimens by the Department of Health and Human Services for the treatment of HIV-1 in ARV-naive patients. A mid-dosing interval therapeutic range between 1,000 and 4,000 ng/mL for efavirenz has been proposed in the literature, with patients more likely to experience virologic failure below this range and adverse effects above. The current study reports an analysis of virologic outcome between those above, below, or within the reported efavirenz therapeutic range (1,000–4,000 ng/mL) and within subgroups. Methods This analysis examined efavirenz plasma concentrations obtained from participants enrolled in AIDS Clinical Trials Group Study A5202. This investigation divided subjects into those who experienced virologic failure and those who did not. These subjects were further separated to investigate those who had “high,” “within,” or “low” plasma concentrations, based on the therapeutic range. The association between virologic failure and plasma concentration was statistically examined in addition to the variables race/ethnicity, sex, assigned nucleos(t)ide reverse transcriptase inhibitor backbone, age at study entry, history of intravenous drug use, weight, and screening HIV-1 RNA stratification level. Results In univariate analyses, a statistically significant difference was found when comparing the efavirenz concentration groups, (22 failures among the “low” concentration group [19%], 65 failures among the “within” concentration group [12%], and 11 failures among the “high” concentration group [9%]) when evaluating virologic failure as an outcome (p = 0.04). In addition, the proportion of participants with virologic failure differed across race/ethnicity groups (p = 0.03) with black non-Hispanic participants observed to have the highest rate (17%). Efavirenz concentration group, race/ethnicity, age, weight, and the interaction between efavirenz concentration group and weight were found to be significantly associated with virologic failure in multivariable logistic regression analysis. Conclusions The proposed efavirenz therapeutic range, combined with the impact of a patient’s weight, is associated with virologic failure in HIV-infected ARV-naive individuals in the United States. Additional analysis is recommended to determine the most appropriate concentration value that defines the lower limit of the efavirenz therapeutic range.

Aim: Determination of paritaprevir and ritonavir in rat liver tissue samples. Results: We successfully validated a UPLC-MS/MS method to measure paritaprevir and ritonavir in rat liver using deuterated internal standards (d8-paritapervir and d6-ritonavir). The method is linear from 20 to 20,000 and 5 to 10,000 pg on column for paritaprevir and ritonavir, respectively, and is normalized per milligram tissue. Interday and intraday variability ranged from 0.591 to 5.33% and accuracy ranged from -6.68 to 10.1% for quality control samples. The method was then applied to the measurement of paritaprevir and ritonavir in rat liver tissue samples from a pilot study. Conclusion: The validated method is suitable for measurement of paritaprevir and ritonavir within rat liver tissue samples for PK studies.

BACKGROUND The use of combination antiretroviral therapy (cART) has significantly decreased the morbidity and mortality associated with HIV infection. Lipid disorders, including lipodystrophy, hypertriglyceridemia, hypercholesterolemia, and dyslipidemia, remain the most commonly reported metabolic disorders among those treated with long-term cART. Mounting evidence suggests an association between drug abuse and poor glycemic control and diabetes complications. Substance related disorders (SRD) may increase the risk of metabolic syndrome. MATERIALS AND METHODS The aim of this retrospective cohort study was to examine the relationship between SRD, cART, and lipid-lowering agent use in an HIV infected population. A total of 276 subjects with HIV infection were included, 90 (33%) received lipid-lowering agents, and 31 (34%) had SRD. Patients received efavirenz or protease inhibitor-based cART for at least 6 months. Prescription information was retrieved from the medical records. The primary outcome was the use of lipid-lowering agents including statins, fibrates and fish oil. The impact of SRD and cART was assessed on the lipid-lowering agent use. RESULTS Smoking was prevalent among subjects with SRD (84% vs. 15%, p<0.001). Statins were the mainstay for the management of dyslipidemia (66%), followed by the fibrates (24%), omega-3 fatty acids (5%), nicotinic acid (3%) and the cholesterol absorption inhibitors (3%). Use of statins or fibrates was significantly higher among subjects without SRD than those with (40% vs. 23%, p=0.005). The type of cART, including efavirenz and protease inhibitors, appeared to have no significant impact on the use pattern of lipid-lowering agents. Lopinavir/r was mostly prescribed for subjects with SRD (25% vs. 8%, p=0.02). CONCLUSIONS Among HIV-infected patients, statins remain the mainstay for the management of dyslipidemia in routine clinical care, followed by fibrates. A significant high risk of metabolic disorders among patients with SRD is implicated by heavy tobacco use and prevalent lopinavir/r-based treatment. Significantly low rate of lipid-lowering agent use in this population underscores the importance of lipid disorder scrutiny and cART treatment optimization for HIV-infected patients with SRD.

Chronic hepatitis C virus (HCV) is a global epidemic, affecting approximately 150 million individuals throughout the world. The implications of HCV infection have been magnified in those who are infected with both HCV and the HIV as liver disease progression, liver failure and liver-related death are increased, particularly in those without well-controlled HIV disease. The development of direct-acting antiviral agents for HCV that allow shorter treatment periods with increased efficacy and decreased adverse events have greatly changed the outlook for HCV-infected individuals. With these advancements, growing treatment options for the coinfected population have also come. This review will address pharmacotherapy issues in the HIV/HCV coinfected population.