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Anlotinib is a new oral tyrosine kinase inhibitor; this study was designed to characterize its pharmacokinetics and disposition. Anlotinib was evaluated in rats, tumor-bearing mice, and dogs and also assessed in vitro to characterize its pharmacokinetics and disposition and drug interaction potential. Samples were analyzed by liquid chromatography/mass spectrometry. Anlotinib, having good membrane permeability, was rapidly absorbed with oral bioavailability of 28%-58% in rats and 41%-77% in dogs. Terminal half-life of anlotinib in dogs (22.8±11.0 h) was longer than that in rats (5.1±1.6 h). This difference appeared to be mainly associated with an interspecies difference in total plasma clearance (rats, 5.35±1.31 L·h·kg; dogs, 0.40±0.06 L·h/kg). Cytochrome P450-mediated metabolism was probably the major elimination pathway. Human CYP3A had the greatest metabolic capability with other human P450s playing minor roles. Anlotinib exhibited large apparent volumes of distribution in rats (27.6±3.1 L/kg) and dogs (6.6±2.5 L/kg) and was highly bound in rat (97%), dog (96%), and human plasma (93%). In human plasma, anlotinib was predominantly bound to albumin and lipoproteins, rather than to α-acid glycoprotein or γ-globulins. Concentrations of anlotinib in various tissue homogenates of rat and in those of tumor-bearing mouse were significantly higher than the associated plasma concentrations. Anlotinib exhibited limited in vitro potency to inhibit many human P450s, UDP-glucuronosyltransferases, and transporters, except for CYP3A4 and CYP2C9 (in vitro half maximum inhibitory concentrations, <1 μmol/L). Based on early reported human pharmacokinetics, drug interaction indices were 0.16 for CYP3A4 and 0.02 for CYP2C9, suggesting that anlotinib had a low propensity to precipitate drug interactions on these enzymes. Anlotinib exhibits many pharmacokinetic characteristics similar to other tyrosine kinase inhibitors, except for terminal half-life, interactions with drug metabolizing enzymes and transporters, and plasma protein binding.

Managing the dysregulated host response to infection remains a major challenge in sepsis care. Chinese treatment guideline recommends adding XueBiJing, a five-herb medicine, to antibiotic-based sepsis care. Although adding XueBiJing further reduced 28-day mortality via modulating the host response, pharmacokinetic herb–drug interaction is a widely recognized issue that needs to be studied. Building on our earlier systematic chemical and human pharmacokinetic investigations of XueBiJing, we evaluated the degree of pharmacokinetic compatibility for XueBiJing/antibiotic combination based on mechanistic evidence of interaction risk. Considering both XueBiJing‒antibiotic and antibiotic‒XueBiJing interaction potential, we integrated informatics-based approach with experimental approach and developed a compound pair-based method for data processing. To reflect clinical reality, we selected for study XueBiJing compounds bioavailable for drug interactions and 45 antibiotics commonly used in sepsis care in China. Based on the data of interacting with drug metabolizing enzymes and transporters, no XueBiJing compound could pair, as perpetrator, with the antibiotics. Although some antibiotics could, due to their inhibition of uridine 5′-diphosphoglucuronosyltransferase 2B15, organic anion transporters 1/2 and/or organic anion-transporting polypeptide 1B3, pair with senkyunolide I, tanshinol and salvianolic acid B, the potential interactions (resulting in increased exposure) are likely desirable due to these XueBiJing compounds' low baseline exposure levels. Inhibition of aldehyde dehydrogenase by 7 antibiotics probably results in undesirable reduction of exposure to protocatechuic acid from XueBiJing. Collectively, XueBiJing/antibiotic combination exhibited a high degree of pharmacokinetic compatibility at clinically relevant doses. The methodology developed can be applied to investigate other drug combinations.

Aim: Monoterpene glycosides derived from Paeonia lactiflora roots (Chishao) are believed to be pharmacologically important for the antiseptic herbal injection XueBiJing. This study was designed to characterize the pharmacokinetics and disposition of monoterpene glycosides. Methods: Systemic exposure to Chishao monoterpene glycosides was assessed in human subjects receiving an intravenous infusion and multiple infusions of XueBiJing injection, followed by assessment of the pharmacokinetics of the major circulating compounds. Supportive rat studies were also performed. Membrane permeability and plasma-protein binding were assessed in vitro. Results: A total of 18 monoterpene glycosides were detected in XueBiJing injection (content levels, 0.001-2.47 mmol/L), and paeoniflorin accounted for 85.5% of the total dose of monoterpene glycosides detected. In human subjects, unchanged paeoniflorin exhibited considerable levels of systemic exposure with elimination half-lives of 1.2-1.3 h; no significant metabolite was detected. Oxypaeoniflorin and albiflorin exhibited low exposure levels, and the remaining minor monoterpene glycosides were negligible or undetected. Glomerular-filtration-based renal excretion was the major elimination pathway of paeoniflorin, which was poorly bound to plasma protein. In rats, the systemic exposure level of paeoniflorin increased proportionally as the dose was increased. Rat lung, heart, and liver exposure levels of paeoniflorin were lower than the plasma level, with the exception of the kidney level, which was 4.3-fold greater than the plasma level; brain penetration was limited by the poor membrane permeability. Conclusion: Due to its significant systemic exposure and appropriate pharmacokinetic profile, as well as previously reported antiseptic properties, paeoniflorin is a promising XueBiJing constituent of therapeutic importance.

XueBiJing, an injectable five-herb preparation, has been incorporated into routine sepsis care in China. Phthalides, originating from XueBiJing's component herbs rhizomes and roots, are believed to contribute to its therapeutic effects due to their presence in the preparation and antisepsis-related properties. This investigation aimed to identify potential therapeutic phthalides that are bioavailable to act on XueBiJing's therapeutic targets and that could serve as pharmacokinetic markers to supplement classic biomarkers for sepsis care. Among 10 phthalides detected in XueBiJing, senkyunolides I and G were the major circulating phthalides in human subjects, but their different pharmacokinetics might influence their contribution to XueBiJing's therapeutic action. Senkyunolide I exhibited a large distribution volume (1.32 l/kg) and was moderately bound in plasma (54% unbound), whereas senkyunolide G exhibited a small distribution volume (0.10 l/kg) and was extensively bound in plasma (3% unbound). Clearance of senkyunolide I from the systemic circulation was governed by UGT2B15-mediated hepatic glucuronidation; the resulting electrophilic glucuronides were conjugated with glutathione in the liver. Senkyunolide G was selectively bound to albumin (99%) in human plasma. To our knowledge, the human pharmacokinetic data of XueBiJing's phthalides are reported here for the first time. Based on this investigation and such investigations of the other component herbs, follow-up pharmacodynamic assessments of bioavailable herbal compounds are planned to elucidate XueBiJing's chemical basis responsible for its therapeutic action. Senkyunolides I and G, having the preceding disposition characteristics that could be detectably altered by septic pathophysiology, could serve as pharmacokinetic markers for sepsis care.

DanHong injection is a Danshen (Salvia miltiorrhiza roots)-based injectable solution for treatment of coronary artery disease and ischemic stroke. Danshen catechols are believed to be responsible for the injection's therapeutic effects. This study aimed to characterize systemic exposure to and elimination of Danshen catechols in human subjects, rats, and dogs receiving intravenous DanHong injection. A total of 28 catechols were detected, with content levels of 0.002-7.066 mM in the injection, and the major compounds included tanshinol, protocatechuic aldehyde, salvianolic acid B, rosmarinic acid, salvianolic acids A and D, and lithospermic acid with their daily doses ‡10 mmol/subject. After dosing, tanshinol, salvianolic acid D, and lithospermic acid exhibited considerable exposure in human subjects and rats. However, only tanshinol had considerable exposure in dogs. The considerable exposure to tanshinol was due to its having the highest dose, whereas that to salvianolic acid D and lithospermic acid was due to their relatively long elimination half-lives in the human subjects and rats. Protocatechuic aldehyde and rosmarinic acid circulated in the bloodstream predominantly as metabolites; salvianolic acids A and B exhibited low plasma levels with their human plasma metabolites little or not detected. Tanshinol and salvianolic acid D were eliminated mainly via renal excretion. Elimination of other catechols involved hepatobiliary and/or renal excretion of their metabolites. Methylation was found to be the primary metabolism for most Danshen catechols and showed intercompound and interspecies differences in rate and degree in vitro. The information gained here is relevant to pharmacological and toxicological research on DanHong injection.

Tanshinol has desirable antianginal and pharmacokinetic properties and is a key compound of Salvia miltiorrhiza roots (Danshen). It is extensively cleared by renal excretion. This study was designed to elucidate the mechanism underlying renal tubular secretion of tanshinol and to compare different ways to manipulate systemic exposure to the compound. Cellular uptake of tanshinol was mediated by human organic anion transporter 1 (OAT1) (K m , 121 mM), OAT2 (859 mM), OAT3 (1888 mM), and OAT4 (1880 mM) and rat Oat1 (117 mM), Oat2 (1207 mM), and Oat3 (1498 mM [BCRP], and rat Oct1, Oct2, Octn1, Octn2, Mate1, Mrp2, Mrp4, and Bcrp) showed either ambiguous ability to transport tanshinol or no transport activity. Rats may be a useful model, to investigate the contribution of the renal transporters on the systemic and renal exposure to tanshinol. Probenecid-induced impairment of tubular secretion resulted in a 3-to 5-fold increase in the rat plasma area under the plasma concentration-time curve from 0 to infinity (AUC 0-' ) of tanshinol. Tanshinol exhibited linear plasma pharmacokinetic properties over a large intravenous dose range (2-200 mg/kg) in rats. The dosage adjustment could result in increases in the plasma AUC 0-' of tanshinol of about 100-fold. Tanshinol exhibited very little doserelated nephrotoxicity. In summary, renal tubular secretion of tanshinol consists of uptake from blood, primarily by OAT1/Oat1, and the subsequent luminal efflux into urine mainly by passive diffusion. Dosage adjustment appears to be an efficient and safe way to manipulate systemic exposure to tanshinol. Tanshinol shows low propensity to cause renal transporter-mediated herb-drug interactions.

XueBiJing injection, prepared from a five-herb combination, is extensively used as add-on therapy in routine sepsis care in China. Catechols, derived from the component herb Salvia miltiorrhiza roots (Danshen), are probably important because of their reported antiseptic properties. This study was designed to characterize pharmacokinetics of major circulating Danshen catechols in human subjects intravenously receiving the injection at the label doses. A total of 17 Danshen catechols were detected in XueBiJing injection (content level, 0.1-139.3 μmol/L). After dosing, tanshinol and salvianolic acid B exhibited relatively high levels of systemic exposure with mean elimination half-lives of 0.38 and 0.29 h, respectively. The total plasma clearance and apparent volume of distribution at steady state of tanshinol were 1.07 L/h/kg and 0.40 L/kg, respectively, whereas those of salvianolic acid B were 0.43 L/h/kg and 0.13 L/kg, respectively. Protocatechuic acid and five other catechols were also detected in plasma but at low exposure levels. Although protocatechuic aldehyde had the highest content level in the injection, like the remaining eight catechols, it was undetected in plasma. Protocatechuic aldehyde was extensively converted into protocatechuic acid and other metabolites. The information gained here facilitates understanding the roles of Danshen catechols in therapeutic actions of XueBiJing injection.