Furmonertinib (Alflutinib, AST2818) is a potential positive control drug comparable to rifampin for evaluation of CYP3A4 induction in sandwich-cultured primary human hepatocytes.

Furmonertinib (Alflutinib, AST2818), as a third-generation epidermal growth factor receptor inhibitor with an advanced efficacy and a relatively wide safety window, has been commercially launched in China recently. However, previous clinical studies demonstrated its time- and dose-dependent clearance in a multiple-dose regimen. In vitro drug metabolism and pharmacokinetic studies have suggested that furmonertinib is mainly metabolized by cytochrome P450 3A4 (CYP3A4) and can induce these enzymes via an increased mRNA expression. This study investigated two important evaluation criteria of CYP3A4 induction by furmonertinib through quantitative proteomics and probe metabolite formation: simultaneous (1) protein expression and (2) enzyme activity with sandwich-cultured primary human hepatocytes in the same well of cell culture plates. Results confirmed that furmonertinib was a potent CYP3A4 inducer comparable with rifampin and could be used as a positive model drug in in vitro studies to evaluate the induction potential of other drug candidates in preclinical studies. In addition, inconsistencies were observed between the protein expression and enzyme activities of CYP3A4 in cells induced by rifampin but not in groups treated with furmonertinib. As such, furmonertinib could be an ideal positive control in the evaluation of CYP3A4 induction. The cells treated with 10 µM rifampin expressed 20.16 ± 5.78 pmol/mg total protein, whereas the cells induced with 0.5 µM furmonertinib expressed 4.8 ± 0.66 pmol/mg protein compared with the vehicle (0.1% dimethyl sulfoxide), which contained 0.65 ± 0.45 pmol/mg protein. The fold change in the CYP3A4 enzyme activity in the cells treated with rifampin was 5.22 ± 1.13, which was similar to that of 0.5 µM furmonertinib (3.79 ± 0.52).

Itraconazole and rifampicin, as CYP3A modulators but not P-gp modulators, affect the pharmacokinetics of almonertinib and active metabolite HAS-719 in healthy volunteers.

Almonertinib is a novel third-generation EGFR tyrosine kinase inhibitor. It is mainly metabolized by CYP3A in vitro, and N-desmethylated almonertinib (HAS-719) is the major active metabolite in human plasma. In this study, we investigated the effects of CYP3A inhibitor itraconazole and CYP3A inducer rifampicin on the pharmacokinetics of almonertinib and HAS-719 in 64 healthy volunteers. We found that when co-administered with itraconazole, the maximal plasma concentration (Cmax) and the plasma exposure (AUC0-t) of almonertinib were increased by 56.3% and 2.38-fold, respectively, whereas the Cmax and AUC0-t of HAS-719 were reduced by 86.8% and 71.8%, respectively. Co-administration with rifampicin reduced the Cmax and AUC0-t of almonertinib by 79.3% and 92.6%, but the AUC0-t of HAS-719 was unexpectedly decreased by 72.5%. In vitro assays showed that both almonertinib and HAS-719 were substrates of CYP3A and P-gp. Co-administration of rifampicin in Beagle dogs reduced the fecal recovery of almonertinib and HAS-719, and markedly increased the levels of metabolites derived from further metabolism of HAS-719, which was consistent with human plasma data, suggesting that although rifampicin was also a potent inducer of P-gp, the pharmacokinetic alternation of HAS-719 was mainly due to its further metabolism but not excretion changes. Moreover, we revealed that almonertinib was a moderately sensitive substrate of CYP3A in vivo. Special attention should be paid to the interaction between almonertinib and drugs or food affecting CYP3A activity in the clinical application of almonertinib.

Alflutinib (AST2818), primarily metabolized by CYP3A4, is a potent CYP3A4 inducer.

Alflutinib (AST2818) is a third-generation epidermal growth factor receptor (EGFR) inhibitor that inhibits both EGFR-sensitive mutations and T790M mutations. Previous study has shown that after multiple dosages, alflutinib exhibits nonlinear pharmacokinetics and displays a time- and dose-dependent increase in the apparent clearance, probably due to its self-induction of cytochrome P450 (CYP) enzyme. In this study, we investigated the CYP isozymes involved in the metabolism of alflutinib and evaluated the enzyme inhibition and induction potential of alflutinib and its metabolites. The data showed that alflutinib in human liver microsomes (HLMs) was metabolized mainly by CYP3A4, which could catalyze the formation of AST5902. Alflutinib did not inhibit CYP isozymes in HLMs but could induce CYP3A4 in human hepatocytes. Rifampin is a known strong CYP3A4 inducer and is recommended by the FDA as a positive control in the CYP3A4 induction assay. We found that the induction potential of alflutinib was comparable to that of rifampin. The Emax of CYP3A4 induction by alflutinib in three lots of human hepatocytes were 9.24-, 11.2-, and 10.4-fold, while the fold-induction of rifampin (10 µM) were 7.22-, 19.4- and 9.46-fold, respectively. The EC50 of alflutinib-induced CYP3A4 mRNA expression was 0.25 µM, which was similar to that of rifampin. In addition, AST5902 exhibited much weak CYP3A4 induction potential compared to alflutinib. Given the plasma exposure of alflutinib and AST5902, both are likely to affect the pharmacokinetics of CYP3A4 substrates. Considering that alflutinib is a CYP3A4 substrate and a potent CYP3A4 inducer, drug-drug interactions are expected during alflutinib treatment.

Nimesulide increases the aldehyde oxidase activity of humans and rats.

An increasing number of drugs are metabolized by aldehyde oxidase (AOX), but AOX-mediated drug interactions are seldom reported due to the lack of appropriate inhibitors and inducers. A recent study reported that nimesulide (NIM) could increase the liver injury risk of methotrexate. The latter was mainly metabolized by AOX to form hepatotoxic 7-hydroxymethotrexate (7-OH MTX). Thus, we speculated that NIM could induce AOX. In this study, we investigated the potential induction of AOX activity by NIM using methotrexate as the probe substrate. Treatment of primary human and rat hepatocytes with NIM (20 µM) for 24 h caused a 2.0- and 3.1-fold, respectively, increase in 7-OH MTX formation. Oral administration of NIM (100 mg·kg-1·d-1, for 5 days) to rats significantly increased the systematic exposure (6.5-fold), liver distribution (2.5-fold), and excretion (5.2-fold for urinary excretion and 2.1-fold for fecal excretion) of 7-OH MTX. The 7-OH MTX formation in liver cytosol from rats pretreated with 20, 50, and 100 mg·kg-1·d-1 NIM for 5 days increased by 1.9-, 3.2-, and 3.7-fold, respectively, compared with that of rats pretreated with the vehicle. We revealed that the elevation of AOX activity was accompanied by an increase in AOX1 protein levels but not the corresponding mRNA levels. Collectively, our results demonstrate for the first time that NIM can increase the AOX activity of humans and rats, and may raise concerns regarding the risk of drug interactions between NIM and AOX substrates in clinical practice.

Potential role of organic anion transporting polypeptide 1B1 (OATP1B1) in the selective hepatic uptake of hematoporphyrin monomethyl ether isomers.

AIM: Hematoporphyrin monomethyl ether (HMME), which consists of equal amounts of isomers HMME-1 and HMME-2, is a novel porphyrin-related drug for photodynamic therapy. This study was aimed to investigate the uptake transporter-mediated selective uptake of HMME into the liver and to identify the major uptake transporter isoforms involved. METHODS: Adult SD rats were intravenously injected with a single dose of HMME (5 mg/kg) with or without rifampicin (an inhibitor of organic anion transporting polypeptides OATP1B1 and OATP1B3, 25 mg/kg). Blood samples were collected, and HMME concentrations were measured using LC-MS/MS. Rat hepatocytes, human hepatocytes and HEK293 cells expressing OATP1B1, OATP1B3, or OATP2B1 were used to investigate the uptake of HMME or individual isomers in vitro. RESULTS: Co-administration of rifampicin significantly increased the exposure of HMME isomers, and decreased the AUC ratio of HMME-1 to HMME-2 from 1.98 to 1.56. The uptake of HMME-2 into human hepatocytes and the HEK293 cells expressing OATP1B1 or OATP2B1 in vitro was 2-7 times greater than that of HMME-1, whereas OATP1B3 mediated a higher HMME-1 uptake. OATP1B1 exhibited a higher affinity for HMME-2 than for HMME-1 (the Km values were 0.63 and 5.61 µmol/L, respectively), which were similar to those in human hepatocytes. By using telmisartan (a non-specific OATP inhibitor) and rifampicin, OATP2B1 was demonstrated to account for <20% of hepatic HMME uptake. CONCLUSION: OATP1B1 is the major transporter involved in the rapid hepatic uptake of HMME, and the greater uptake of HMME-2 by OATP1B1 may lead to a lower exposure of HMME-2 than HMME-1 in humans.

Chemical constituents from Saussurea cordifolia.

Thirty-six naturally occurring compounds, including four C(10)-acetylenic glycosides and a lignan, were isolated from the whole plants of Saussurea cordifolia. Their structures were elucidated by means of spectroscopic and chemical methods to be 4,6-decadiyne-1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (1), 4,6-decadiyne-1-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (2), (8E)-decaene-4, 6-diyn-1-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (3), (8Z)-decaene-4,6-diyn-1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside (4), and (2R,3S,4S)-4-(4-hydroxy-3-methoxybenzyl)-2-(5-hydroxy-3-methoxyphenyl)-3-(hydroxymethyl)-tetrahydrofuran-3-ol (5).