A First-in-Human Trial of GLS4, a Novel Inhibitor of Hepatitis B Virus Capsid Assembly, following Single- and Multiple-Ascending-Oral-Dose Studies with or without Ritonavir in Healthy Adult Volunteers

GLS4 is a novel inhibitor of the hepatitis B virus (HBV) capsid assembly with inhibitory activities against nucleot(s)ide-resistant HBV strains. This study investigated the pharmacokinetics, safety, and tolerability of GLS4 and the effects of food and ritonavir in healthy adults. GLS4 was administered in a single-ascending-dose study over 1 to 240 mg and multiple-ascending-dose study that ranged from 30 mg once daily to 180 mg three times daily. The drug interaction study included sequential design (day 1 for 120 mg GLS4 alone, day 5 for 100 mg ritonavir alone, followed by 9 days of both drugs) and a placebo control (9 days of both 240 mg GLS4 and 100 mg ritonavir). The results showed that the steady-state trough concentration of multiple dosing of GLS4 alone was significantly lower than the 90% effective concentration of 55.7 ng/ml, even with increasing dosing frequency and dosage. An initial dose of 100 mg ritonavir significantly boosted plasma concentration at 24 h of 120 mg GLS4 from 2.40 to 49.8 ng/ml (geometric mean ratio, 20.7; 90% confidence interval, 17.0 to 25.3), while a milder effect was observed on the area under the curve from 0 to 24 h, with a 7.42-fold increase, and on the maximum concentration, with a 4.82-fold increase. The pharmacokinetics change in GLS4 persisted after 9 days of chronic dosing, with a trough concentration of 182 ng/ml. Both single and multiple doses of GLS4 up to 240 mg with or without ritonavir were well tolerated. These results support the investigation of a novel HBV treatment regimen containing GLS4 with 100 mg ritonavir added solely to enhance GLS4 concentrations in plasma. (This study was registered at the China Platform for Registry and Publicity of Drug Clinical Trials [http://www.chinadrugtrials.org.cn] under numbers CTR20132137 and CTR20150230.).

Quantitative Prediction of Regioselectivity Toward Cytochrome P450/3A4 Using Machine Learning Approaches

In the drug discovery process, it is important to know the properties of both drug candidates and their metabolites. Fast and precise prediction of metabolites is essential. However, it has been difficult to predict metabolites because of the complexity of the mechanism of cytochrome P450/3A4 (CYP 3A4), which is the main metabolite enzyme of drugs. In this study, we focus on the regioselectivity of CYP 3A4, i.e., the selectivity of metabolic sites. We have developed a model to predict the regioselectivity of drug candidates by using machine learning (ML) approaches.

Effect of Cinnamomum cassia on the Pharmacokinetics and Pharmacodynamics of Pioglitazone

BACKGROUND

Millions of people today use herbs either as food or in the form of medicine along with other medications. Many of the herbs can interact with these medications, causing either potentially dangerous side effects or improved or reduced benefits from the medication.

OBJECTIVE

The present study was performed to determine the influence of cinnamon, on the pharmacokinetics and pharmacodynamics of pioglitazone.

METHOD

Studies were conducted in normal and alloxan induced diabetic rats and rabbits with oral administration of selected doses of pioglitazone, cinnamon and their combination. Blood samples were collected at regular intervals of time and were analysed for glucose by GOD/POD method and for pioglitazone by HPLC method respectively. Body weights were also measured every week.

RESULTS

Significant differences were seen in pharmacokinetic parameters of pioglitazone like AUC, t1/2, Ke, Cl/F, Vd/F when given in combination with cinnamon in normal and diabetic rabbits. The combination of pioglitazone and cinnamon was found to reduce the glucose levels and body weights significantly than pioglitazone. The results indicating increased AUC of pioglitazone on pretreatment with cinnamon suggest an interaction indicating decreased metabolism of pioglitazone as a result of CYP 3A4 inhibition and thereby producing a potentiating effect.

CONCLUSION

Cinnamon enhanced the bioavailability of pioglitazone by inhibiting the CYP3A4 enzyme. Hence, cinnamon might be beneficial when used in combination with pioglitazone in diabetic patients and an adjustment of dose of pioglitazone may be necessary.

Interaction of clopidogrel and statins in secondary prevention after cerebral ischaemia - a randomized, double-blind, double-dummy crossover study

AIMS

Variability in responsiveness to clopidogrel is a clinical problem in secondary prevention after cerebral ischaemia which has been suggested to be linked to competitive metabolization of clopidogrel and cytochrome P450 (CYP) 3A4-oxidated statins such as simvastatin. We assessed the hypothesis that simvastatin, in contrast to CYP 2C9-metabolized fluvastatin, reduces clopidogrel-mediated platelet inhibition.

METHODS

We performed a randomized, double-blind, double-dummy, two period crossover study in 13 patients with cerebral ischaemia (8F, 5 M), aged 64.1 ± 8.0 years (mean ± SD). After a 14 day period in which all patients received 75 mg clopidogrel day(-1) , patients additionally received either 20 mg simvastatin day(-1) or 80 mg fluvastatin day(-1) for 14 days. Regimens were crossed over after a 14 day wash-out period and switched regimens were continued for another 14 days. Platelet aggregation, clopidogrel active metabolite (CAM) plasma concentrations and routine laboratory parameters including prothrombin time (PT) Quick percent value were assessed at baseline and following each treatment phase.

RESULTS

Clopidogrel reduced platelet aggregation in all patients as expected. Platelet aggregation and CAM plasma concentrations were unaltered when simvastatin or fluvastatin was added to clopidogrel. Simvastatin decreased PT Quick percent value (decrease from 109 ± 10.5% to 103 ± 11%, P < 0.05) when combined with clopidogrel but there was no such change following treatment with fluvastatin and clopidogrel.

CONCLUSIONS

Our data indicate that treatment with CYP 3A4-metabolized simvastatin does not jeopardize clopidogrel-mediated inhibition of platelet aggregation. After co-administration of simvastatin and clopidogrel we observed a decrease in the PT Quick percent value which could be due to simvastatin-induced reduction of activity of prothrombin fragment 1 + 2.

Severe sunitinib-induced myelosuppression in a patient with a CYP 3A4 polymorphism

Sunitinib, an oral vascular endothelial growth factor receptor, is a first-line option for metastatic renal cell carcinoma and widely used in clinical practice. Despite the proven benefit of sunitnib in metastatic renal cell carcinoma, patients may suffer from a variety of adverse events including hypertension, fatigue, hypothyroidism, hand-foot skin reactions, rash, depigmentation, and myelosuppression. Myelosuppression is usually mild, transient and resolves during the two weeks at the end of each cycle where no drug is taken. We present a case of severe and early grade 3 neutropenia and thrombocytopenia occurring two weeks into a six-week cycle. Because of the extreme nature of the toxicity, CYP 3A4 polymorphisms were explored. The patient was found to be heterozygous for CYP 3A4*22, at least partially explaining the early-onset and severity of myelosuppression. This pharmacogenetics information resulted in a rechallenge of dose-reduced sunitinib, which was well tolerated by the patient. The current state of pharmacogenomics concerning sunitinb is also presented, and the need for greater research in this area is highlighted.

Degradation of pristine and oxidized single wall carbon nanotubes by CYP3A4

Carbon nanotubes (CNTs) are a class of carbon based nanomaterials which have attracted substantial attention in recent years as they exhibit outstanding physical, mechanical and optical properties. In the last decade many studies have emerged of the underlying mechanisms behind CNT toxicity including malignant transformation, the formation of granulomas, inflammatory responses, oxidative stress, DNA damage and mutation. In the present investigation, we studied the biodegradation of single-walled carbon nanotubes (SWCNTs) by Cytochrome P450 enzymes (CYP3A4) through using Raman spectroscopy. CYP3A4 is known isozyme accountable for metabolizing various endogenous and exogenous xenobiotics. CYP3A4 is expressed dominantly in the liver and other organs including the lungs. Our results suggest that CYP3A4 has a higher affinity for p-SWNTs compared to c-SWNTs. HEK293 cellular viability was not compromised when incubated with SWNT. However, CYP3A4 transfected HEK293 cell line showed no digestion of c-SWNTs after incubation for 96 h. Cellular uptake of c-SWNTs was observed by electron microscopy and localization of c-SWNTs was confirmed in endosomal vesicles and in the cytoplasm. This is the first study CYP3A4 degrading both p-SWNTs and c-SWNTs in an in vitro setup. Interestingly, our results show that CYP3A4 is more proficient in degrading p-SWNTs than c-SWNTs. We also employed computational modeling and docking assessments to develop a further understanding of the molecular interaction mechanism.

Differences of Atomic-Level Interactions between Midazolam and Two CYP Isoforms 3A4 and 3A5

CYP 3A4 and CYP 3A5 are two important members of the human cytochrome P450 family. Although their overall structures are similar, the local structures of the active site are different, which directly leads to obvious individual differences in drug metabolic efficacy and toxicity. In this work, midazolam (MDZ) was selected as the probe substrate, and its interaction with two proteins, CYP 3A4 and CYP 3A5, was studied by molecular dynamics simulation (MD) along with the calculation of the binding free energy. The results show that two protein-substrate complexes have some similarities in enzyme-substrate binding; that is, in both complexes, Ser119 forms a high occupancy hydrogen bond with MDZ, which plays a key role in the stability of the interaction between MDZ and the enzymes. However, the complex formed by CYP 3A4 and MDZ is more stable, which may be attributed to the sandwich structure formed by the fluorophenyl group of the substrate with Leu216 and Leu482. Our study interprets the binding differences between two isoform-substrate complexes and reveals a structure-function relationship from the atomic perspective, which is expected to provide a theoretical basis for accurately measuring the effectiveness and toxicity of drugs for individuals in the era of precision medicine.

Phase 1 study to evaluate the effects of rifampin or itraconazole on the pharmacokinetics of limertinib (ASK120067), a novel mutant-selective inhibitor of the epidermal growth factor receptor in healthy Chinese subjects

BACKGROUND

Limertinib is a novel mutant-selective and irreversible inhibitor of the epidermal growth factor receptor under development. A phase 1 open, two-period, single-sequence, self-controlled, two-part study was initiated to characterize the effects of a strong CYP3A4 inducer (rifampin) or inhibitor (itraconazole) on the pharmacokinetics of limertinib.

RESEARCH DESIGN AND METHODS

Twenty-four healthy subjects in each part received a single dose of limertinib alone (160 mg, Part A; 80 mg, Part B) and with multiple doses of rifampin 600 mg once daily (Part A) or itraconazole 200 mg twice daily (Part B).

RESULTS

Coadministration of rifampin decreased exposure (area under the plasma concentration-time curve from time 0 to infinity, AUC0-inf) of limertinib and its active metabolite CCB4580030 by 87.86% (geometric least-squares mean [GLSM] ratio, 12.14%; 90% confidence interval [CI], 9.89-14.92) and 66.82% (GLSM ratio, 33.18%; 90% CI, 27.72-39.72), respectively. Coadministration of itraconazole increased the AUC0-inf of limertinib by 289.8% (GLSM ratio, 389.8%; 90% CI, 334.07-454.82), but decreased that of CCB4580030 by 35.96% (GLSM ratio, 64.04%; 90% CI, 50.78-80.77).

CONCLUSIONS

Our study demonstrates that the concomitant use of limertinib with strong CYP3A inducers or inhibitors is not recommended. A single dose of limertinib, administered with or without rifampin or itraconazole, is generally safe and well tolerated in healthy Chinese subjects.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier is NCT05631678.

Study of the Urinary Ratio of 6 beta-Hydroxycortisol/Cortisol as a Biomarker of CYP3A4 Activity in Egyptian Patients with Chronic Liver Diseases

The urinary ratio of 6 beta-hydroxycortisol/cortisol (6 beta-OHC/C) as a biomarker of CYP3A4 metabolizing activity has been studied in Egyptian patients with chronic liver cirrhosis associated with previous hepatic Schistosomiasis infection to determine any possible alteration in enzyme activity. The ratio of 6-beta OHC/C was determined in morning urine samples collected from 8:00 a.m. to 12:00 p.m. in healthy adults (n = 36) and patients with liver cirrhosis (n = 57). The median age for control was 27 years (range: 18-50 years) and 50 years (range: 27-75 years) for patients. 6 beta-OHC was detected in urine by ELIZA kits (Stabiligen, France). Patients with liver cirrhosis were categorized according to Child Pugh Classification into Child B (n = 28) and Child C (n = 29) classes. Cholestasis was observed in 9/28 of Child B class and 8/29 of Child C class of patients. The control subjects showed gender-related difference in the urinary ratio of 6 beta-OHC/C. A significant reduction (P < 0.001) in 6 beta-OHC/C ratio was observed only in Child C patients in comparison with control subjects. Regression analysis showed a significant correlation (P < 0.05) between 6 beta-OHC/C ratio and serum albumin. The influence of cholestasis on the urinary ratio of 6-beta OHC/C was observed on cirrhotic patients of Child B class. In conclusion, patients with chronic liver cirrhosis might have a reduction of metabolizing activity of CYP3A4 enzymes which could be identified by measuring the urinary ratio of 6 beta-OHC/C. This reduction is more apparent in severe liver injury (Child C class). Therefore, it is important to understand the metabolic fate of drugs metabolized by 3A4 enzymes in patients with liver cirrhosis to avoid drug accumulation that might lead to development of drug toxicity.

Gepirone-the latest antidepressant on market state-of-the-art or run-of-the-mill?

Gepirone was recently launched and FDA-approved for MDD. It belongs to azapirones group of psychotropics that is in popular use in Japan and China. Here, author wraps up current knowledge on gepirone contrasted with the older and cheaper anxiolytic buspirone.

In Vitro metabolism of six representative organic UV stabilizers (OUVs) in marine fish liver microsomes: Kinetics, mechanisms and bioaccumulation evaluation

The ubiquitous occurrence of organic UV stabilizers (OUVs) poses a potential threat to marine fish, but the metabolism of OUVs in the body remains a missing piece of the puzzle in their ecotoxicology. This study investigated the in vitro metabolism of six OUVs in the liver microsomes of an economically valuable marine fish (Lateolabrax japonicus). The depletion of the six OUVs follows first-order kinetics in the microsomes, with in vitro depletion rate constants (kdepl) ranging from 0.23 to 0.40/h. The intrinsic clearance (CLint) of 1H-benzotriazole (BT) was estimated to be 0.0026 μL/(min·mg·protein). The enzyme inhibition experiments and molecular docking results highlight the importance of cytochrome P450 enzyme (CYP) 3A4 in OUVs metabolism. Among the 4 metabolizable compounds, some metabolites from hydroxylation, methylation, acetylation and conjugation were tentatively identified. In addition, the in vitro transformation rates can more accurately predict the whole-body bioconcentration potential via an in vitro to in vivo extrapolation (IVIVE) model.

Drug-drug interactions with direct oral anticoagulants for the prevention of ischemic stroke and embolism in atrial fibrillation: a narrative review of adverse events

INTRODUCTION

In randomized trials, direct oral anticoagulants (DOAC) were non-inferior to the vitamin-K-antagonist (VKA) warfarin in preventing stroke/embolism in patients with atrial fibrillation (AF). DOAC are substrates for P-glycoprotein (P-gp), CYP3A4 and CYP2C9. The activity of these enzymes is modulated by several drugs which might induce pharmacokinetic drug-drug interactions (DDI). Drugs affecting platelet function have the potential for pharmacodynamic DDI of DOAC.

AREAS COVERED

The literature was searched for: 'dabigatran,' 'rivaroxaban,' 'edoxaban,' or 'apixaban' and drugs affecting platelet function, CYP3A4-, CYP2C9- or P-gp-activity. Reports about bleeding and embolic events attributed to DDI with DOAC in AF-patients were found for 43 of 171 drugs with interacting potential (25%), most frequently with antiplatelet and nonsteroidal anti-inflammatory drugs. Whereas a co-medication of platelet-affecting drugs is invariably reported to increase the bleeding risk, the findings regarding P-gp-, CYP3A4- and CYP2C9- activity-affecting drugs are ambiguous.

EXPERT OPINION

Tests for plasma DOAC-levels and information about DDI of DOAC should be widely available and user-friendly. If advantages and disadvantages of DOAC and VKA can be investigated exhaustively, individualized anticoagulant therapy can be offered to patients, considering co-medication, comorbidities, genetic and geographic factors and the health care system.

Could chronic opioid use be an additional risk of hepatic damage in patients with previous liver diseases, and what is the role of microbiome?

Among illicit drugs, addiction from opioids and synthetic opioids is soaring in an unparalleled manner with its unacceptable amount of deaths. Apart from these extreme consequences, the liver toxicity is another important aspect that should be highlighted. Accordingly, the chronic use of these substances, of which fentanyl is the most frequently consumed, represents an additional risk of liver damage in patients with underlying chronic liver disease. These observations are drawn from various preclinical and clinical studies present in literature. Several downstream molecular events have been proposed, but recent pieces of research strengthen the hypothesis that dysbiosis of the gut microbiota is a solid mechanism inducing and worsening liver damage by both alcohol and illicit drugs. In this scenario, the gut flora modification ascribed to non-alcoholic fatty liver disease performs an additive role. Interestingly enough, HBV and HCV infections impact gut-liver axis. In the end, the authors tried to solicit the attention of operators on this major healthcare problem.