Pharmacokinetics-based Identification Of Potential Therapeutic Phthalides From XueBiJing,A Chinese Herbal Injection Used In Sepsis Management

Background and aim: XueBiJing injection is a five-herb combination,prepared from Carthamus tinctorius flowers(Honghua in Chinese),Paeonia lactiflora roots(Chishao),Ligusticum chuanxiong rhizomes(Chuanxiong),Angelica sinensis roots(Danggui),and Salvia miltiorrhiza roots and rhizomes(Danshen),and has been commonly incorporated into routine sepsis care as an add-on therapy.Despite the promising clinical results with low incidence of side effects,little is known about the injection’s chemical basis responsible for its antiseptic activity.Multi-compound pharmacokinetic research on herbal medicine has been proposed to facilitate identifying such chemical basis by identifying the herbal compounds bioavailable to interact with the therapeutic targets.Hence,pharmacokinetic research on four types of herbal compounds,which are present in XueBiJing injection and are reported to have antisepsis-related pharmacological properties,was conducted.As a part of our ongoing study,the current investigation focused on Chuanxiong/Danggui phthalides.Methods: Pharmacokinetic studies of XueBiJing were conducted in healty human subjects,rats,and in vitro.In the human study,36 healthy volunteers were recruited to receive a single dose and multiple doses of XueBiJing.For single-dose administration,the following three dosage regimens were designed,i.e.,a 1.25-h infusion of 100 ml XueBiJing,a 2.5-h infusion of 100 ml XueBiJing,and a 1.25-h infusion of 50 ml XueBiJing,while that for multiple-dose administration was a 1.25-h infusion of 50 ml XueBiJing for seven consecutive days.Rat pharmacokinetic studies included a doseascending study,urinary,biliary,and fecal excretory studies,a tissue distribution study,and a pharmacokinetic matrix effect study.In vitro pharmacokinetic studies could be divided into two parts based on the experimental purpose.Plasma protein binding assessment and identification,membrane permeability assessment,and blood-plasma partition assessment were conducted to help identify the in vivo reach of XueBiJing phthalides.In vivo metabolites characterization,key elimination pathway identification,key metabolites synthesis and structure elucidation,and key enzyme identification and the associated enzyme kinetic assessments were conducted to help identify the elimination of XueBiJing phthalides.The samples were analyzed using liquid chromatography/mass spectrometry.Results: Among 10 phthalides(content level,0.2-29.3 μM)detected in XueBiJing,senkyunolides I and G were the major circulating phthalides in human subjects who intravenously received the injection.Despite their levels of high systemic exposure,the pharmacokinetic characteristics of the two phthalides were markedly different.Senkyunolide I had a medium plasma binding(46% bound),a large distribution volume(1.3 l/kg),and a medium total plasma clearance(23.6% of the cardiac output),whereas senkyunolide G had an extensive plasma binding(97% bound),a small distribution volume(0.1 l/kg),and a low total plasma clearance(1% of the cardiac output).The differences of the preceding pharmacokinetic characteristics may influence their reach to therapeutic targets.Moreover,two phthalides exhibited specific characteristics detectably altered by sepsis pathophysiology.These characteristics included: 1)UGT2B15-mediated hepatic glucuronidation of senkyunolide I governing its clearance from the systemic circulation,2)the resulting alkyl glucuronides formed being electrophilic and conjugated with glutathione,and 3)senkyunolide G being extensively and selectively bound to human plasma albumin.Conclusion: To our knowledge,the pharmacokinetic data of XueBiJing phthalides in human are reported here for the first time.Senkyunolides I and G are the major circulating phthalides in human subjects and are worth further investigation with respect to antisepsis-related pharmacodynamic properties.Senkyunolides I and G,having disposition characteristics that could be detectably altered by septic pathophysiology,could serve as pharmacokinetic markers to supplement classic biomarkers for sepsis care.