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GLS4 is a first‐in‐class hepatitis B virus (HBV) capsid assembly modulator (class I) that is co‐administered with ritonavir to maintain the anticipated concentration required for the effective antiviral activity of GLS4. In this study, the first physiologically‐based pharmacokinetic (PBPK) model for GLS4/ritonavir was successfully developed. The predictive performance of the PBPK model was verified using data from 39 clinical studies, including single‐dose, multiple‐dose, food effects, and drug–drug interactions (DDI). The PBPK model accurately described the PK profiles of GLS4 and ritonavir, with predicted values closely aligning with observed data. Based on the verified GLS4/ritonavir model, it prospectively predicts the effect of hepatic impairment (HI) and DDI on its pharmacokinetics (PK). Notably, CYP3A4 inducers significantly influenced GLS4 exposure when co‐administered with ritonavir; co‐administered GLS4 and ritonavir significantly influenced the exposure of CYP3A4 substrates. Additionally, with the severity of HI increased, there was a corresponding increase in the exposure to GLS4 when co‐administered with ritonavir. The GLS4/ritonavir PBPK model can potentially be used as an alternative to clinical studies or guide the design of clinical trial protocols. [ABSTRACT FROM AUTHOR]

Background and Objective: There is an unmet need for a safer anticoagulant since bleeding remains a concern with currently approved anticoagulants. Coagulation factor XI (FXI) is an attractive anticoagulant drug target with limited a role in physiological hemostasis. The objective of this study was to evaluate the safety, pharmacokinetics, and pharmacodynamics of SHR2285, a novel small molecule FXIa inhibitor, in healthy Chinese volunteers. Methods: The study consisted of single ascending doses part (part 1: 25–600 mg) and multiple ascending doses part (part 2: 100, 200, 300, and 400 mg). In both parts, subjects were randomized in a 3:1 ratio to receive SHR2285 or placebo orally. Blood, urine and feces samples were collected to describe its pharmacokinetic and pharmacodynamic profile. Results: In total, 103 healthy volunteers completed the study. SHR2285 was well tolerated. SHR2285 was absorbed rapidly with median time to maximum plasma concentration (Tmax) of 1.50 to 3.00 h. The geometric median half-life (t1/2) of SHR2285 varied from 8.74 to 12.1 h across 25–600 mg single dose. Total systemic exposure of metabolite SHR164471 was approximately 1.77- to 3.61-fold that of the parent drug. The plasma concentration of SHR2285 and SHR164471 reached steady state by the morning of Day 7, with low accumulation ratio (0.956–1.20 and 1.18–1.56, respectively). The increase in pharmacokinetic exposure of SHR2285 and SHR164471 was less than dose proportional. Food has minimal effect on the pharmacokinetics of SHR2285 and SHR164471. SHR2285 produced an exposure-dependent prolongation of activated partial thromboplastin time (APTT) and a decrease in FXI activity. The maximum FXI activity inhibition rate (geometric mean) at steady state was 73.27%, 85.58%, 87.77% and 86.27% for 100–400 mg, respectively. Conclusions: SHR2285 was generally safe and well tolerated in healthy subjects across a wide range of doses. SHR2285 exhibited a predictable pharmacokinetic profile and an exposure-related pharmacodynamic profile. ClinicalTrials.gov Identifier NCT04472819; registered on July 15, 2020. [ABSTRACT FROM AUTHOR]

Background: Data available for pharmacokinetics (PK)/pharmacodynamics (PD) of ticagrelor and significant endogenous/exogenous factors or biomarkers related to bleeding events in both healthy and clinical patients are limited. Objective: Based on PK and PD data from multicenter healthy subjects and patients, we aimed to establish an integrated approach towards population PK (pop PK) and the PD model of ticagrelor. Methods: This study was conducted as a multicenter, prospective clinical registration study involving both healthy subjects and clinical patients. The integrated Pharmacokinetic/pharmacodynamic (PK/PD) models were characterized based on PK/PD [ticagrelor concentration, aggregation baseline (BASE), P2Y12 response unit (PRU) and inhibition rate (INHIBIT)] data from 175 healthy volunteers. The model was corrected by sparse PD (BASE, PRU and INHIBIT) data from 208 patients with acute coronary syndrome (ACS). The correlations between PD biomarkers and clinically relevant bleedings in 1 year were explored. Results: A one-compartment, linear model with first-order absorption was adopted as PK model. Food status (FOOD) and body weight (WT) significantly influenced clearance and improved the fitting degree of the PK model, while SEX was selected as the covariates of the PD model. For patients taking ticagrelor 90 mg, the peak value [mean (95% CI)] of PRU was 355.15 (344.24–366.06) and the trough value was 3.64 (3.14–4.15). The PRU mean parameters were basically within the expected range (80–200) of the literature suggestions. Conclusion: A fixed dose of ticagrelor, without adjusting the dosing regimen other than covariates of FOOD/WT/SEX, could be used in patients with acute coronary syndromes, and the standard regimen could be used in Chinese patients from the perspective of exposure. [ABSTRACT FROM AUTHOR]

LY03004, a novel investigational risperidone long-acting injection (LAI) microsphere formulation, can release risperidone more quickly after injection than Risperdal Consta®. This study aimed to investigate the effects of genetic polymorphisms on the pharmacokinetics of LY03004 compared with those on Risperdal Consta®. A total of 100 Chinese patients with stable schizophrenia were randomly assigned to the LY03004 or Risperdal Consta® treatment group. Each patient received five biweekly intramuscular injections of 25 mg risperidone long-acting injection microspheres. A total of 34 blood samples before and after injections from Day 1 to Day 113 were collected from each patient, and polymorphic alleles of cytochrome P450 enzymes CYP2D6 (*4, *10, *14), CYP3A5 (*3), and ABCB1 (C1236 > T, G2677T/A , and C3435T) were analyzed using Sanger sequencing and polymerase chain reaction-restriction fragment length polymorphism. The risperidone C max,ss , C min,ss , AUC 0-tau,ss , and the ratio of risperidone to 9-hydroxyrisperidone (9-OH-R) in CYP2D6 intermediate metabolizers (IMs) were significantly different compared with those in normal metabolizers (NMs) in both the LY03004 and Risperdal Consta® groups (P < 0.05). However, 9-OH-R was not significantly different between IMs and NMs (P > 0.05). The AUC 0-tau,ss of the active moiety (risperidone plus 9-OH-R) was 6.51 ± 3.34 in NMs and 7.00 ± 1.81 in IMs (P = 0.071) in the LY03004 group and 6.07 ± 2.31 and 7.95 ± 3.42 (P = 0.053) in NMs and IMs, respectively, in the Risperdal Consta® group. In the LY03004 group, the C max,ss of risperidone in carriers of the ABCB1-C3435T TT variant was significantly lower than that in CC and CT carriers (TT 7.76 ± 4.23 ng/mL, CT 11.6 ± 8.27 ng/mL, CC 14.3 ± 7.66 ng/ml; P = 0.045), but no significant differences were found in the active moiety. In the Risperdal Consta® group, C3435T TT carriers had significantly lower C min,ss of the active moiety (TT 5.09 ± 4.38 ng/mL, CT 11.4 ± 8.42 ng/mL, CC 14.3 ± 6.43 ng/mL; P = 0.007). Furthermore, C min,ss of the active moiety was significantly different among all ABCB1-G2677T/A genotypes (P < 0.05). The pharmacokinetics of risperidone and the ratio of risperidone to 9-OH-R were highly dependent on CYP2D6 activity. However, there was no significant effect in 9-OH-R. A future study involving a larger sample is required to verify whether CYP2D6 IMs have lower risperidone active moiety clearance than CYP2D6 NMs for LAI formulations. In addition, the risperidone active moiety was eliminated faster in ABCB1-G2677T/A and C3435T TT carriers receiving Risperdal Consta®. • We analyzed the effects of CYP2D6, 3A5, and ABCB1 gene polymorphisms on the pharmacokinetics of risperidone LAIs in Chinese. • IMs had significantly higher exposure to risperidone than CYP2D6 NMs; however, no significant difference in 9-OHRIS. • IMs probably had higher active moiety exposure than NMs, but a study with a larger sample is required to verify the results. • G2677TA and C3435T TT carriers receiving Risperdal Consta® injection had significantly lower C min,ss of the active moiety. • Formulation may be an influence factor that affects the level of risperidone exposure differences among different genotypes. [ABSTRACT FROM AUTHOR]