Beta-thalassemia major alters sofosbuvir/ledipasvir exposure in Hepatitis C virus infected adolescent patients.

BACKGROUND: Hepatitis C virus (HCV) infected adolescents with beta-thalassemia major (BTM) are considered a potential population for HCV micro-elimination model development where BTM may negatively impact the pharmacokinetic exposure parameters of sofosbuvir/ledipasvir (SOF/LED). OBJECTIVES: The study aimed at studying the effect of BTM on SOF/LED and SOF metabolite (GS-331007) pharmacokinetics. METHODS: A prospective, controlled study recruiting BTM and control HCV infected adolescents (Clinicaltrials.gov identifier-NCT04353986). Pharmacokinetic exposure to GS-331007 and LED was the primary pharmacokinetic outcome. No-effect boundaries were set to 90% confidence interval (CI) of exposure geometric mean ratio (GMR) within 70-143%. Dose suitability was based on the 90% CI of exposure GMR within 50-200% compared to adults. The percentage of patients achieving sustained virologic response 12 weeks post-treatment (SVR12) was the primary efficacy endpoint. RESULTS: Thirteen patients were enrolled per study group. All patients were included in the pharmacokinetic analysis (n=26). BTM patients showed lower GS-331007 and LED exposure that could, respectively, be as low as 45.4% and 36.1% compared to their control group. GS-331007 exposure in BTM patients was nearly half (56.8%, 90% CI 45.3-71.2%) that observed in adults. Despite that low drug exposure in 46.2% of BTM patients may alert dose unsuitability, they achieved SVR12. Moreover, patients with total bilirubin ≥1.93 mg/dL were predicted to have low GS-331007 exposure (0.913 receiver operating characteristic area under the curve with sensitivity and specificity >80%). CONCLUSION AND RELEVANCE: The identified systematically lower drug exposure in BTM patients might partially explain relapses or treatment failures among BTM patients reported in other studies. BTM may be a hurdle towards implementing HCV micro-elimination model that may necessitate dose-adjustment.

Obesity Does Not Affect Propofol Pharmacokinetics During Hypothermic Cardiopulmonary Bypass.

OBJECTIVE: Because of the lack of data regarding the impact of obesity on propofol pharmacokinetics in patients undergoing cardiac surgery using hypothermic cardiopulmonary bypass (CPB), the authors sought to explore propofol pharmacokinetics and develop a predictive pharmacokinetic model that characterizes and predicts propofol pharmacokinetics in this population. DESIGN: A prospective, observational study. SETTING: A teaching hospital. PARTICIPANTS: The study comprised 17 obese and 17 control (nonobese) patients undergoing hypothermic CPB. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Patients mainly underwent valve surgery. On initiation of hypothermic CPB (28°C-32°C), patients received a propofol (1%) bolus (1 mg/kg) immediately followed by a 2 mg/kg/h infusion. Blood samples were withdrawn at the following times: before dosing; 1, 3, 5, and 7 minutes after the propofol bolus dose; every 20 minutes during infusion; just before discontinuation of the infusion; and at 1, 3, 5, 7, 10, 20, 30, and 60 minutes after discontinuation of the infusion. The plasma propofol concentration was determined using high-performance liquid chromatography, and then data were imported into Monolix (Lixoft, Antony, France) for population pharmacokinetic modeling and pharmacokinetic parameters estimation. A 2-compartment pharmacokinetic model with age as a covariate on the peripheral volume of distribution (V2) best described the pooled data. The pooled data was internally evaluated successfully to describe and predict propofol pharmacokinetics in the addressed population. Propofol clearance, intercompartmental clearance, and central volume of distribution were 805 mL/min, 1140 mL/min and 18.8 L, respectively. V2 was calculated as 9.86×exp.(1.88×[age/40]) L. CONCLUSION: Propofol pharmacokinetic parameters were similar in obese and nonobese patients undergoing hypothermic CPB. Age was the major determinant of propofol V2 in the obese population.