A randomized phase 1b trial of the active site polymerase inhibitor nucleotide ATI-2173 in patients with chronic hepatitis B virus infection.

ATI-2173 is an active site polymerase inhibitor nucleotide in development as part of a potentially curative regimen for chronic hepatitis B virus (HBV) infection. This study evaluated the safety, tolerability, pharmacokinetics (PK) and antiviral activity of ATI-2173. This was a phase 1b, randomized, double-blind, placebo-controlled trial in treatment-naive adults with chronic HBV infection conducted in the Republic of Moldova and Ukraine (ClinicalTrials.gov: NCT04248426). Patients positive for hepatitis B surface antigen were randomized 6:2 to receive once-daily oral doses of ATI-2173 10, 25, or 50 mg (n = 6 per dose) or placebo (n = 7) for 28 days, with off-treatment monitoring for 24 weeks. Endpoints included PK parameters of ATI-2173 and its metabolite clevudine, maximum reduction from baseline in HBV DNA, and safety and tolerability. Treatment-emergent adverse events occurred in eight patients (47%) receiving ATI-2173 and five (71%) receiving placebo; headache was the most common (n = 4). ATI-2173 PK was generally dose proportional. Systemic clevudine exposure with ATI-2173 dosing was substantially reduced compared with historical values observed with clevudine administration. On Day 28, mean changes from baseline in HBV DNA were -2.72 to -2.78 log10  IU/ml with ATI-2173 and +0.17 log10  IU/ml with placebo. Off-treatment sustained viral suppression and decreases in covalently closed circular DNA biomarkers were observed in most patients; one maintained undetectable HBV DNA at 24 weeks off treatment. In this 28-day monotherapy study, ATI-2173 demonstrated safety and antiviral activity, with sustained off-treatment effects and substantially reduced systemic clevudine exposure. These results support evaluation of ATI-2173 with tenofovir disoproxil fumarate in phase 2 studies.

Development and validation of probe drug cocktails for the characterization of CYP450-mediated metabolism by human heart microsomes.

1. The objective of our study was to develop and validate a cocktail approach to allow the simultaneous characterization of various CYP450-mediated oxidations by human heart microsomes for nine probe drug substrates, namely, 7-ethoxyresorufin, bupropion, repaglinide, tolbutamide, bufuralol, chlorzoxazone, ebastine, midazolam and dodecanoic acid. 2. The first validation step was conducted using recombinant human CYP450 isoenzymes by comparing activity measured for each probe drug as a function of (1) buffer used, (2) selectivity towards specific isoenzymes and (3) drug interactions between probes. Activity was all measured by validated LC-MSMS methods. 3. Two cocktails were then constituted with seven of the nine drugs and subjected to kinetic validation. Finally, all probe drugs were incubated with human heart microsomes prepared from ventricular tissues obtained from 12 patients undergoing cardiac transplantation. 4. Validated cocktail #1 including bupropion, chlorzoxazone, ebastine and midazolam was used to characterize CYP2B6-, 2E1-, 2J2- and 3A5-mediated metabolism in human hearts. 5. Cocktail #2 which includes bufuralol, 7-ethoxyresorufin and repaglinide failed the validation step. Substrates in cocktail #2 as well as tolbutamide and dodecanoic acid had to be incubated separately because of their physico-chemical characteristics (solubility and ionization) or drug interactions. 6. Activity in HHM was the highest towards ebastine, chlorzoxazone and tolbutamide.

The bioequivalence of fixed-dose combination tablets of bisoprolol and ramipril and its drug-drug interaction potential.

Chronic antihypertensive treatment often includes combination of two or more therapies with complementary mechanism of action targeting different blood pressure (BP) control system. If available, these components are recommended to be administered as a fixed-dose combination (FDC) to reduce tablet burden, improve adherence and thus BP control. A combination of ramipril (RAMI) and bisoprolol (BISO) is one of the options used in clinical practice and is supported by therapeutic guidelines. The clinical program for a novel BISO/RAMI FDC consisted of two randomized, open-label, bioequivalence (BE) studies and one drug-drug interaction (DDI) study. The BE was examined between two FDC strengths of BISO/RAMI (10/10 and 10/5 mg) and the individual reference products administered concomitantly at respective doses after a single oral dose under fasting conditions. In both BE studies, 64 healthy subjects were randomized according to a two-way crossover design. The DDI study evaluated a potential pharmacokinetic (PK) interaction between BISO 10 mg and RAMI 10 mg following their single or concomitant administrations in 30 healthy subjects under fasting condition. BE for BISO/RAMI 10/5 mg and absence of a clinically relevant PK DDI between BISO and RAMI was demonstrated as the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) for area under the concentration time curve (AUC) and maximum concentration (Cmax ) remained within the acceptance range of 80.00 to 125.00%. However, BE for BISO/RAMI 10/10 mg was not demonstrated, as the lower bound of the 90% CI of Cmax for RAMI was outside the acceptance range of BE. Both drugs administered alone or combined were well-tolerated. No PK interaction was observed between BISO and RAMI/ramiprilat, since the co-administration of BISO and RAMI 10 mg single doses resulted in comparable rate and extent of absorption for BISO and RAMI when compared to their individual products.