Zhi-Yi Zhang

Development and validation of a liquid chromatography–tandem mass spectrometry assay for the simultaneous quantitation of prednisolone and dipyridamole in human plasma and its application in a pharmacokinetic study

We have developed and validated an accurate, sensitive, and robust LC-MS/MS method that determines the concentration of CRx-102 (the combination of prednisolone and dipyridamole) in human plasma. In this method, prednisolone, dipyridamole, and the combined internal standards (IS) prednisolone-d(6) (IS for prednisolone) and dipyridamole-d(20) (IS for dipyridamole) were extracted from 100 microL human EDTA plasma using methylbutyl ether. Calibration curves were linear over a concentration range of 0.4-200 ng/mL for prednisolone and 5-3000 ng/mL for dipyridamole. The analytes were quantitatively determined using tandem mass spectrometry operated in positive electrospray ionization in a multiple reaction monitoring (MRM) mode. This validated method has been used successfully in clinical pharmacokinetic studies of CRx-102 in healthy volunteers.

Biotransformation and in vitro assessment of metabolism-associated drug–drug interaction for CRx-102, a novel combination drug candidate

CRx-102 is an oral synergistic combination drug which contains the cardiovascular agent, dipyridamole (DP) and a very low dose of the glucocorticoid, prednisolone (PRED). CRx-102 works through a novel mechanism of action in which DP selectively amplifies the anti-inflammatory activity of PRED without replicating its side effects. CRx-102 is in clinical trials for the treatment of osteoarthritis. Here we delineate the in vitro metabolism and explore the potential for a drug-drug interaction between the active agents in CRx-102. Our study using human hepatocyte suspensions showed that both DP and PRED were metabolized by CYP3A4 isozymes, resulting in the formation of diverse arrays of both oxidative and oxidative-reduced metabolites. Within phase 1 biotransformation, CYP3A4 was one of the pathways responsible for the metabolism of PRED, while phase 2 biotransformation played a significant role in the metabolism of DP. Glucuronidation of DP was substantial and was catalyzed by many UGT members, specifically those in the UGT1A subfamily. Based on the tandem mass (MS/MS) product ion spectra (PIS) acquired, the major metabolites of both agents, namely, monooxygenated, mono-N-deethanolaminated, dehydrogenated and O-glucuronidated metabolites of DP and the monooxygenated (e.g., 6-hydroxyl), dehydrogenated (prednisone) and reduced (20-hydroxyl) metabolites of PRED, were identified and elucidated. The affinities for DP biotransformation, including CYP3A4-mediated oxidative pathways and UGT-mediated O-glucuronidation, appeared high (K(m)<10 microM), as compared with the modest affinities of PRED biotransformation catalyzed by CYP3A4 (K(m) approximately 40-170 microM). DP, but not PRED, exerted a minimal inhibitory effect on the drug-metabolizing CYP isoforms, including CYP3A4, which was determined using a panel of CYP isoform-preferred substrate activities in pooled human liver microsomal (HLM) preparations and microsomal preparations containing the recombinant enzymes (K(i) approximately 2-12 microM). Using the DP maximal plasma concentration (C(max)) observed in the clinic and a predictive mathematical model for metabolism-associated drug-drug interaction (DDI), we have demonstrated that there is little likelihood of a pharmacokinetic interaction between the two active agents in CRx-102.

Bioequivalence of Intravenous and Oral Rolapitant: Results From a Randomized, Open‐Label Pivotal Study

Rolapitant, a selective and long‐acting neurokinin‐1 receptor antagonist, is approved in an oral formulation for the prevention of delayed chemotherapy‐induced nausea and vomiting in adults. The objective of this pivotal study was to assess the bioequivalence of a single intravenous infusion of rolapitant versus a single oral dose of rolapitant. In this randomized, open‐label phase 1 study, healthy volunteers were administered rolapitant as a 180‐mg oral dose or a 30‐minute 166.5‐mg intravenous infusion. Blood samples for pharmacokinetic analysis were collected predose and at points up to 912 hours postdose. Criteria for bioequivalence of the intravenous dose versus the oral dose were met if the 90% confidence intervals (CIs) for the ratios of the geometric least‐squares means (GLSMs) for the area under the plasma concentration‐time curve (AUC) from time 0 to the time of the last quantifiable concentration (AUC0–t) and AUC from time 0 extrapolated to infinity (AUC0–∞) for rolapitant were within 0.80–1.25. Mean rolapitant systemic exposure and half‐lives were similar in the oral (n = 62) and intravenous (n = 61) rolapitant groups. The 90%CIs of the ratio of GLSMs were within the 0.80–1.25 range for AUC0–t (0.94–1.09) and AUC0–∞ (0.93–1.10). The incidence of treatment‐emergent adverse events, all mild or moderate in severity, was similar in the intravenous and oral groups. A 166.5‐mg intravenous infusion of rolapitant met the bioequivalence criteria based on AUC to a 180‐mg oral dose and was well tolerated.

Effects of Rolapitant Administered Intravenously or Orally on the Pharmacokinetics of Digoxin (P‐glycoprotein Substrate) and Sulfasalazine (Breast Cancer Resistance Protein Substrate) in Healthy Volunteers

Rolapitant is a selective and long‐acting neurokinin‐1 receptor antagonist approved in an oral formulation in combination with other antiemetic agents for the prevention of delayed chemotherapy‐induced nausea and vomiting in adults. Four open‐label phase 1 studies evaluated the safety and drug–drug interactions of a single dose of rolapitant given intravenously (166.5 mg) or orally (180 mg) with oral digoxin (0.5 mg) or sulfasalazine (500 mg), probe substrates for the P‐glycoprotein (P‐gp) and breast cancer resistance protein (BCRP), respectively. Administration of intravenous rolapitant with the substrates did not result in clinically significant effects on digoxin and sulfasalazine pharmacokinetics. In contrast, peak concentration and area under the curve for last quantifiable plasma concentrations increased by 71% (geometric mean ratio [GMR], 1.71; 90% confidence interval [CI], 1.49–1.95) and 30% (GMR, 1.30; 90%CI, 1.19–1.42), respectively, when rolapitant was coadministered orally with digoxin compared with digoxin alone; they increased by 140% (GMR, 2.40; 90%CI, 2.02–2.86) and 127% (GMR, 2.27; 90%CI, 1.94–2.65), respectively, when rolapitant was given orally with sulfasalazine compared with sulfasalazine alone. Adverse events were mild to moderate in severity in the absence or presence of rolapitant. There were no abnormal clinical laboratory or electrocardiogram findings. Thus, whether administered orally or intravenously, rolapitant was safe and well tolerated. Patients taking oral rolapitant with P‐gp and BCRP substrates with a narrow therapeutic index should be monitored for potential adverse events; although increased plasma concentrations of these substrates may raise the risk of toxicity, they are not contraindicated.

Abstract C63: Effects of rolapitant on the pharmacokinetics of digoxin and sulfasalazine in healthy subjects

Introduction: Rolapitant is a selective and long acting NK-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting (CINV). In vitro results indicated that rolapitant inhibited P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), the efflux transporters that play important roles in drug disposition and distribution, with an IC50 of 7.4 μM and 4.6 μM, respectively. The major metabolite SCH720881 did not inhibit these transporters. The aims of these studies were to 1) evaluate the effects of rolapitant on the pharmacokinetics (PK) and pharmacodynamics (PD) of a P-gp substrate (digoxin), and on the PK of a BCRP substrate (sulfasalazine); and 2) evaluate the safety and tolerability of rolapitant co-administered with these substrates in healthy subjects. Methods: These were open-label, drug-drug interaction studies of orally administered substrate (0.5 mg of digoxin or 500 mg sulfasalazine, respectively) in the absence and presence of a single oral dose of 180 mg rolapitant. Cohorts consisted of 16 and 20 subjects, respectively. For the P-gp study, blood samples for digoxin PK were collected up to 96 hours post digoxin dose in both Period 1 (digoxin alone) and Period 2 (digoxin + a single dose of rolapitant). For PD evaluation, ECGs were performed at specified time points for both Periods 1 and 2. For the BCRP study, blood samples were collected up to 30 hours after Day 1 (sulfasalazine alone), Day 3 (sulfasalazine + rolapitant) and Day 10 (sulfasalazine alone) dosing. All samples were used to evaluate the impact of rolapitant and its major metabolite, SCH720881, on the PK of the relevant substrates. Results: Co-administration of digoxin with rolapitant increased mean digoxin Cmax value by 71% and mean AUC by 30%; trough concentrations were not impacted. There is no consistent pattern or trend to indicate a different PD profile of digoxin when administered with rolapitant. Digoxin administered either alone or in the presence of rolapitant was well tolerated. Rolapitant inhibited BCRP resulting in an increase in exposure of sulfasalazine. Geometric mean ratios were 2.4 and 1.2 for Cmax; 2.3 and 1.3 for AUC for the comparison of Day3/Day1 and Day10/Day1, respectively. There were no noteworthy adverse events or laboratory findings in this study. Conclusions: Rolapitant was well tolerated when co-administered with either the P-gp or BCRP substrate. Co-administration of rolapitant (180 mg) and digoxin (0.5 mg) had no clinically meaningful effect on PD response when compared with digoxin alone. Co-administration of rolapitant (180 mg) increased the exposure of sulfasalazine (500 mg) by approximately 2-fold. Monitoring for adverse reactions related to P-gp or BCRP substrates with a narrow therapeutic index may be necessary if rolapitant is concomitantly administered. Citation Format: Xiaodong Wang, Zhi-Yi Zhang, Sujata Arora, Lorraine Hughes, Jing Wang, Sharon Lu, Jennifer Christensen, Vikram Kansra. Effects of rolapitant on the pharmacokinetics of digoxin and sulfasalazine in healthy subjects. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C63.

Abstract C62: Effects of rolapitant on the pharmacokinetics of dextromethorphan (CYP2D6), tolbutamide (CYP2C9), omeprazole (CYP2C19), efavirenz (CYP2B6), and repaglinide (CYP2C8) in healthy subjects

Introduction: Rolapitant is a selective and long acting NK-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting (CINV). In vitro results indicated rolapitant mildly inhibited cytochrome P450 (CYP450) enzymes (2D6/2C9/2C19/2B6/2C8) at high concentrations (IC50s > 7 μM). The major metabolite SCH720881 did not inhibit these CYP enzymes. This study aimed to 1) evaluate the effects of rolapitant on the pharmacokinetics (PK) of CYP probe substrates (dextromethorphan [DET] for CYP2D6, tolbutamide [TOL] for CYP2C9, omeprazole [OMP] for CYP2C19, efavirenz [EFA] for CYP2B6 and repaglinide [REP] for CYP2C8), and 2) evaluate the safety and tolerability of rolapitant co-administered with these substrates in healthy subjects. Methods: This was an open-label, multi-part drug-drug interaction study in cohorts of 20 to 26 healthy subjects of orally-administered CYP probe substrates (Part-A: 30 mg DET; Part-B: 500 mg TOL plus 40 mg OMP; Part-C: 600 mg EFA; Part-D: 0.25 mg REP) in the absence and presence of single oral dose 180 mg rolapitant. Blood samples for determination of plasma concentration of CYP substrates and relevant metabolites were collected during 3 dosing periods in each part: 1) Period-1: CYP probe substrate alone as baseline; 2) Period-2: CYP probe substrate plus rolapitant concomitantly after a washout of probe given in Period 1 to evaluate the potential impact of rolapitant on probe substrate; and 3) Period-3: CYP probe substrate alone 7 days after the concomitant dose in Period-2 (approximating the peak time of metabolite SCH720881) to evaluate the impact of metabolite/rolapitant on probe substrate. Results: Rolapitant inhibited CYP2D6 following concomitant dose (Period-2) and 7 days after concomitant dose (Period-3), resulting in 2.2- to 3.3-fold higher exposure (Cmax and AUC) of DET. Rolapitant did not inhibit CYP2C9 following exposure to TOL. The exposure (Cmax & AUC) of CYP2C19 substrate OMP was minimally increased by rolapitant (1.1- to1.4-fold) and is unlikely to be clinically relevant. Rolapitant did not inhibit CYP2B6 or result in clinically relevant changes in exposure of EFA. Rolapitant did not inhibit CYP2C8 or result in clinically relevant changes in exposure of REP. There were no noteworthy adverse events or laboratory findings in any part of the study. Conclusions: Rolapitant was well-tolerated when co-administered with CYP probe substrates. Co-administration of rolapitant increased the exposure of DET. The inhibition of CYP2D6 can last at least 7 days following single dose of rolapitant. No clinically significant interaction was observed between rolapitant and substrates of CYP2C9, CYP2C19, CYP2B6 or CYP2C8; therefore no dosing adjustment is necessary for drugs which are metabolized by these CYPs. Citation Format: Xiaodong Wang, Zhi-Yi Zhang, Jing Wang, Sharon Lu, Sujata Arora, Lorraine Hughes, Jennifer Christensen, Vikram Kansra. Effects of rolapitant on the pharmacokinetics of dextromethorphan (CYP2D6), tolbutamide (CYP2C9), omeprazole (CYP2C19), efavirenz (CYP2B6), and repaglinide (CYP2C8) in healthy subjects. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C62.

Effects of Rolapitant Administered Intravenously on the Pharmacokinetics of a Modified Cooperstown Cocktail (Midazolam, Omeprazole, Warfarin, Caffeine, and Dextromethorphan) in Healthy Subjects

Rolapitant is a selective, long‐acting neurokinin‐1 receptor antagonist, approved in the United States and Europe for prevention of delayed chemotherapy‐induced nausea and vomiting in adults. This open‐label study evaluated the effects of a new intravenous formulation of rolapitant on cytochrome P450 (CYP) enzyme (CYP3A, CYP1A2, CYP2C9, CYP2C19, and CYP2D6) activity. On days 1 and 14, 36 healthy volunteers received a modified Cooperstown cocktail (midazolam 3 mg [CYP3A substrate], caffeine 200 mg [CYP1A2 substrate], S‐warfarin 10 mg [CYP2C9 substrate] + vitamin K 10 mg, omeprazole 40 mg [CYP2C19 substrate], and dextromethorphan 30 mg [CYP2D6 substrate]). On day 7, subjects received the modified Cooperstown cocktail after 166.5‐mg rolapitant infusion. On days 21, 28, and 35, subjects received oral dextromethorphan. Maximum plasma concentration (Cmax) and area under the plasma concentration‐time curve (AUC0‐last) of probe drugs post‐ vs pre–rolapitant administration were assessed using geometric least‐squares mean ratios (GMRs) with 90%CIs. The 90%CIs of the GMRs were within the 0.80–1.25 no‐effect limits for caffeine and S‐warfarin Cmax and AUC0‐last. For midazolam Cmax and AUC0‐last and omeprazole Cmax, the 90%CIs of the GMRs were marginally outside these limits. Intravenous rolapitant coadministration increased dextromethorphan exposure, peaking 14 days post–rolapitant administration (GMRs: Cmax, 2.74, 90%CI 2.21–3.40; AUC0‐last, 3.36, 90%CI 2.74–4.13). Intravenous rolapitant 166.5 mg and probe drugs were well tolerated when coadministered. These data suggest that intravenous rolapitant is not an inhibitor of CYP3A, CYP2C9, CYP2C19, or CYP1A2 but is a moderate inhibitor of CYP2D6.

Pharmacokinetics of Rolapitant in Patients With Mild to Moderate Hepatic Impairment

Rolapitant is a selective and long‐acting neurokinin‐1 receptor antagonist approved in an oral formulation in combination with other antiemetic agents for the prevention of delayed chemotherapy‐induced nausea and vomiting in adults. This was a phase 1 open‐label, parallel‐group pharmacokinetic and safety study of a single oral dose of 180 mg of rolapitant and its major active metabolite, M19, in subjects with mild and moderate hepatic impairment compared with healthy matched controls. Pharmacokinetics were assessed by a mixed‐model analysis of variance of log‐transformed values for maximum observed plasma concentration (Cmax), observed time at Cmax (tmax), area under the plasma concentration–time curve (AUC) from time 0 to the time of the last quantifiable concentration (AUC0–t), and AUC from time 0 to 120 hours (AUC0–120), with hepatic group as a fixed effect. Mean rolapitant Cmax, AUC0–t, and AUC0–120 were similar in the mild hepatic impairment and healthy control groups. In subjects with moderate hepatic impairment, AUC0–t was similar and Cmax was 25% lower than in healthy controls. Mean M19 Cmax and AUC0–t were similar in the mild hepatic impairment group and healthy controls, but <20% lower in those with moderate hepatic impairment versus healthy controls. Fraction of unbound rolapitant was comparable in all groups for rolapitant and M19. Rolapitant was well tolerated in all groups, without serious adverse events. Pharmacokinetic differences between healthy subjects and those with mild or moderate hepatic impairment are unlikely to pose a safety risk and do not warrant predefined dosage adjustment in the presence of hepatic impairment.

A Phase 1 Assessment of the QT Interval in Healthy Adults Following Exposure to Rolapitant, a Cancer Supportive Care Antiemetic

This 2‐part study evaluated the QT/QTc prolongation potential and safety and pharmacokinetics of the antiemetic rolapitant, a neurokinin‐1 receptor antagonist. Part 1 was a randomized, placebo‐controlled single‐dose‐escalation study assessing the safety of a single high dose of rolapitant. Part 2 was a randomized, placebo‐ and positive‐controlled, double‐blind parallel‐group study including 4 treatment arms: rolapitant at the highest safe dose established in part 1, placebo, moxifloxacin 400 mg (positive control), and rolapitant at the presumed therapeutic dose (180 mg). Among 184 adults, rolapitant was absorbed following oral administration under fasting conditions, with a median Tmax of 4 to 6 hours (range, 2–8 hours) and was safe at all doses up to 720 mg. No differences in mean change in QTcF were observed between placebo and rolapitant from baseline or at any point. At any point, the upper bound of the confidence interval for the mean difference between placebo and rolapitant was no greater than 4.4 milliseconds, and the mean difference between placebo and rolapitant was no greater than 1.7 milliseconds, suggesting an insignificant change in QTc with rolapitant. Rolapitant is safe and does not prolong the QT interval at doses up to 720 mg relative to placebo in healthy adults.

Pharmacokinetics, Safety, and Tolerability of Rolapitant Administered Intravenously Following Single Ascending and Multiple Ascending Doses in Healthy Subjects

Rolapitant is a selective and long‐acting neurokinin‐1 receptor antagonist approved in an oral formulation in combination with dexamethasone and a 5‐hydroxytryptamine type 3 receptor antagonist for the prevention of delayed chemotherapy‐induced nausea and vomiting in adults. The pharmacokinetic and safety profiles of intravenous (IV) rolapitant were evaluated in two open‐label, phase 1 trials in healthy subjects. Single ascending dose (SAD) and multiple ascending dose studies were conducted in one trial (PR‐11‐5012‐C), and a supratherapeutic SAD study was conducted in a separate trial (PR‐11‐5022‐C). In the SAD and supratherapeutic studies, rolapitant maximum plasma concentration, area under the plasma drug concentration‐time curve (AUC) from time zero to time of last measured concentration, and AUC from time zero to infinity increased dose‐proportionally following single IV infusions of 18 to 270 mg. In the multiple ascending dose study, following 10 daily IV infusions of rolapitant 18, 36, or 54 mg, the mean day 10:day 1 maximum concentration ratio was 1.97, 1.52, and 2.07, respectively, and the mean day 10:day 1 ratio of AUC from 0 to 24 hours was 4.30, 4.59, and 5.38, respectively, indicating drug accumulation over time. Across all studies, rolapitant was gradually eliminated from plasma, with a half‐life of 135‐231 hours. Rolapitant was safe and well tolerated across all studies, with no serious or severe rolapitant‐related treatment‐emergent adverse events. The most common rolapitant‐related treatment‐emergent adverse events were headache, dry mouth, and dizziness, which were predominantly mild in severity. Overall, the pharmacokinetic and safety profiles of IV rolapitant were consistent with those of the oral formulation.