Twenty-eight day safety, antiviral activity, and pharmacokinetics of tenofovir alafenamide for treatment of chronic hepatitis B infection.

BACKGROUND & AIMS: Tenofovir alafenamide, a phosphonate prodrug of tenofovir with greater plasma stability than tenofovir disoproxil fumarate, provides efficient delivery of active drug to hepatocytes at reduced systemic tenofovir exposures. METHODS: Non-cirrhotic, treatment-naïve subjects with chronic hepatitis B were randomized (1:1:1:1:1) to receive tenofovir alafenamide 8, 25, 40, or 120 mg, or tenofovir disoproxil fumarate 300 mg for 28 days and assessed for safety, antiviral response, and pharmacokinetics, followed-up by off-treatment for 4 weeks. RESULTS: 51 subjects were randomized and all completed study treatment. Groups were generally well matched (67% male, 57% Asian, 53% HBeAg-negative, mean HBV DNA approximately 6.0 log10 IU/ml) with HBV genotypes reflective of the population. No subject experienced an adverse event that was serious or severe (grade 3/4). Across the tenofovir alafenamide groups, similar mean changes in serum HBV DNA were found at Week 4 (-2.81, -2.55, -2.19, and -2.76 log10 IU/ml for the 8, 25, 40, and 120 mg groups, respectively) which were also comparable to the control (-2.68 log10 IU/ml for tenofovir disoproxil fumarate 300 mg). Kinetics of viral decline were also similar among groups. Tenofovir alafenamide pharmacokinetics were linear and proportional to the dose; doses⩽25 mg were associated with ⩾92% reductions in mean tenofovir area under the curve relative to tenofovir disoproxil fumarate 300 mg. CONCLUSIONS: Tenofovir alafenamide was safe and well tolerated; declines in HBV DNA were similar to tenofovir disoproxil fumarate at all doses evaluated. Tenofovir alafenamide 25 mg has been selected for further hepatitis B clinical development.

Omeprazole limited sampling strategies to predict area under the concentration-time curve ratios: implications for cytochrome P450 2C19 and 3A phenotyping.

PURPOSE: To develop a limited sampling strategy (LSS) to predict area under the concentration-time curve (AUC) ratios of omeprazole (AUC(OPZ)) to its metabolites 5-hydroxyomeprazole (AUC(5OH)) and omeprazole sulfone (AUC(SUL)) as phenotyping parameters for cytochrome P450 (CYP) 2C19 and 3A. METHODS: Data were obtained from 37 (4 women) Caucasian, Chinese, and Korean healthy adults from three published studies. The AUC(OPZ), AUC(5OH), and AUC(SUL) were calculated via noncompartmental analysis. Observed AUC(OPZ, OBS)/AUC(5OH, OBS) and AUC(OPZ, OBS)/AUC(SUL, OBS) were determined. Plasma concentrations of omeprazole, 5-hydroxyomeprazole, and omeprazole sulfone at 1, 1.5, 2, 3, 4, 6, and 8 h post-dose were used to generate limited sampling strategy (LSS) models to predict AUC(OPZ,PRE)/AUC(5OH,PRE) and AUC(OPZ,PRE/)AUC(SUL,PRE). Bias and precision were assessed via percentage mean prediction error (%MPE) and percentage mean absolute error (%MAE), with acceptable limits being <15%. RESULTS: For CYP2C19, the AUC(OPZ,OBS)/AUC(5OH,OBS) was [mean ± standard deviation (SD)] 2.10 ± 1.63. Five LSS models of AUC(OPZ,PRE)/AUC(5OH,PRE) were generated, but none met the bias or precision criteria. Upon stratification by CYP2C19 genotype and ethnicity, a three-timepoint (at 1, 2, and 4 h) LSS model accurately predicted AUC(OPZ)/AUC(5OH) in Caucasian CYP2C19*1/*1 subjects. For CYP3A, AUC(OPZ,OBS)/AUC(SUL,OBS) (mean ± SD) was 1.79 ± 0.67. All LSS models had unacceptable %MAE, even when stratified by CYP2C19 genotype and ethnicity. CONCLUSIONS: A LSS model to predict AUC(OPZ)/AUC(5OH), and thus CYP2C19 activity, was generated for Caucasian CYP2C19*1/*1 subjects. However, additional model validation is needed prior to general use. LSS models to predict AUC(OPZ)/AUC(SUL), and thus CYP3A activity, were not possible, even upon stratification by CYP2C19 genotype and ethnicity.

Insulin infusion to treat severe hypertriglyceridemia associated with pegaspargase therapy: a case report.

We describe a pediatric patient with acute leukemia who developed an uncommon but significant metabolic consequence of pegaspargase therapy-severe hypertriglyceridemia (hyperTG). We also relate our experience with continuous insulin infusion treatment for pegaspargase-induced hyperTG. This treatment approach led to a decrease in triglycerides from 4640 mg/dL on admission to 522 mg/dL at discharge 9 days later. Genetic testing revealed that our patient was an apolipoprotein E 3/4 heterozygote. Our review of the literature suggests that apolipoprotein E polymorphism may influence the development of hyperlipidemia in acute lymphoblastic leukemia patients receiving asparaginase therapy and may identify patients at high risk for developing asparaginase-induced hyperTG.