Olajide E. Olaleye

Systemic Exposure to and Disposition of Catechols Derived from Salvia miltiorrhiza Roots (Danshen) after Intravenous Dosing DanHong Injection in Human Subjects, Rats, and Dogs

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 μmol/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.

Renal Tubular Secretion of Tanshinol: Molecular Mechanisms, Impact on Its Systemic Exposure, and Propensity for Dose-Related Nephrotoxicity and for Renal Herb-Drug Interactions

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) (Km, 121 μM), OAT2 (859 μM), OAT3 (1888 μM), and OAT4 (1880 μM) and rat Oat1 (117 µM), Oat2 (1207 μM), and Oat3 (1498 μM). Other renal transporters (human organic anion-transporting polypeptide 4C1 [OATP4C1], organic cation transporter 2 [OCT2], carnitine/organic cation transporter 1 [OCTN1], multidrug and toxin extrusion protein 1 [MATE1], MATE2-K, multidrug resistance-associated protein 2 [MRP2], MRP4, and breast cancer resistance protein [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 (AUC0–∞) 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 AUC0–∞ of tanshinol of about 100-fold. Tanshinol exhibited very little dose-related 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.

Pharmacokinetics and disposition of monoterpene glycosides derived from Paeonia lactiflora roots (Chishao) after intravenous dosing of antiseptic XueBiJing injection in human subjects and rats

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.

Pharmacokinetics of catechols in human subjects intravenously receiving XueBiJing injection, an emerging antiseptic herbal medicine

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.

Simultaneous determination of eight Danshen polyphenols in rat plasma and its application to a comparative pharmacokinetic study of DanHong injection and Danshen injection

Polyphenols derived from Danshen are responsible for the therapeutic effects of DanHong injection, a two-herb combination of Danshen and Honghua. Whether the pharmacokinetics of Danshen polyphenols is changed by coexisting Honghua constituents remains unknown. A sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed in this study for simultaneous determination of eight Danshen polyphenols (i.e., protocatechuic aldehyde, protocatechuic acid, tanshinol, salvianolic acid D, rosmarinic acid, salvianolic acid A, lithospermic acid, and salvianolic acid B) in rat plasma and applied to a comparative pharmacokinetic study of DanHong injection and Danshen injection. Liquid chromatography conditions, mass spectrometry parameters, and sample preparation were optimized step by step. The calibration curves showed good linearity (r > 0.99) for all the polyphenols. The mean extraction efficiencies ranged from 62.2 to 88.7% with negligible matrix effects. The intrabatch and interbatch precision at all the quality control levels were less than 15% of the nominal concentrations with accuracy of 88.8-114%, except that precision and accuracy at lower limit of quantitation were 3.2-17.3 and 95.7-119%, respectively. Comparative pharmacokinetic study suggested that the coexisting Honghua constituents might have negligible influences on the pharmacokinetics of Danshen polyphenols from DanHong injection. The bioanalytical method could also be applied to pharmacokinetic studies of other Danshen herbal products.

Pharmacokinetics and disposition of anlotinib, an oral tyrosine kinase inhibitor, in experimental animal species

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−1·kg−1; dogs, 0.40±0.06 L·h−1/kg−1). 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 α1-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.

Pharmacokinetics and Disposition of Circulating Iridoids and Organic Acids in Rats Intravenously Receiving ReDuNing Injection

ReDuNing injection, prepared from a combination of Gardenia Jasminoides fruits, Lonicera japonica flower buds, and the Artemisia annua aerial part, is extensively used for treatment of viral upper respiratory tract infections in China. Iridoids, organic acids, and flavonoids are likely important compounds of the herbal injection because of their reported pharmacological properties. This study was designed to characterize pharmacokinetics and disposition of the major circulating herbal compounds in rats that received the injection intravenously. ReDuNing injection was found to contain 19 iridoids (content levels 0.01–27.93 mM), 16 organic acids (0.04–19.06 mM), and 11 flavonoids (<0.08 mM). After dosing the injection, the iridoids geniposide, secologanic acid, secoxyloganin, genipin-1-β-gentiobioside, geniposidic acid, sweroside, and shanzhiside and the organic acids chlorogenic acid, quinic acid, cryptochlorogenic acid, and neochlorogenic acid were found to be the major circulating compounds, with mean elimination half-lives of 0.2–0.9 hour; the other plasma compounds were at low exposure levels. These major circulating compounds exhibited small apparent volumes of distribution (0.03–0.34 l/kg). Most of the iridoids were eliminated predominantly via renal excretion of the unchanged compounds, whereas the organic acids were eliminated via methylation and sulfation and were excreted into urine as the unchanged and metabolized compounds. The methylated metabolites also underwent subsequent conjugations before hepatobiliary and renal excretion. In vitro data suggested that the metabolism of the organic acids in rats also occurred in humans. The current pharmacokinetic research could serve as a crucial step in identifying the chemical basis responsible for the therapeutic action of ReDuNing injection.

Assay development for determination of DZ2002, a new reversible SAHH inhibitor, and its acid metabolite DZA in blood and application to rat pharmacokinetic study

Methyl (S)-4-(6-amino-9H-purin-9-yl)-2-hydroxybutanoate (DZ2002) is a potent reversible inhibitor of S-adenosyl-L-homocysteine hydrolase (SAHH). Due to its ester structure, DZ2002 is rapidly hydrolyzed in rat blood to 4-(6-amino-9H-purin-9-yl)-2-hydroxybutyric acid (DZA) during and after blood sampling from rats; this hampers accurate determination of the circulating DZ2002 and its acid metabolite DZA in rats. To this end, a method for determining the blood concentrations of DZ2002 and DZA in rats was developed by using methanol to immediately deactivate blood carboxylesterases during sampling. The newly developed bioanalytical assay possessed favorable accuracy and precision with lower limit of quantification of 31 nM for DZ2002 and DZA. This validated assay was applied to a rat pharmacokinetic study of DZ2002. After oral administration, DZ2002 was found to be extensively converted into DZA. The level of systemic exposure to DZ2002 was significantly lower than that of DZA. The apparent oral bioavailability of DZ2002 was 90%–159%. The mean terminal half-lives of DZ2002 and DZA were 0.3–0.9 and 1.3–5.1 h, respectively. The sample preparation method illustrated here may be adopted for determination of other circulating ester drugs and their acid metabolites in rodents.

Pharmacokinetics-Based Identification of Potential Therapeutic Phthalides from XueBiJing, a Chinese Herbal Injection Used in Sepsis Management

XueBiJing, an injectable five-herb preparation, has been incorporated into routine sepsis care in China. Phthalides, originating from XueBiJing’s component herbs Ligusticum chuanxiong rhizomes and Angelica sinensis 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 XueBiJings 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.

Glycyrrhizin has a high likelihood to be a victim of drug–drug interactions mediated by hepatic organic anion‐transporting polypeptide 1B1/1B3

Intravenous glycyrrhizin, having anti‐inflammatory and hepatoprotective properties, is incorporated into the management of liver diseases in China. This investigation was designed to elucidate the molecular mechanism underlying hepatobiliary excretion of glycyrrhizin and to investigate its potential for drug–drug interactions on organic anion‐transporting polypeptide (OATP)1B.