Cedirogant Population Pharmacokinetics and Pharmacodynamic Analyses of Interleukin-17A Inhibition in Two Phase 1 Studies in Healthy Participants and Participants with Moderate to Severe Psoriasis

Cedirogant (ABBV-157) is an orally bioavailable inverse agonist of retinoic acid-related orphan receptor gamma thymus. Data from 2 Phase 1 studies were used to characterize cedirogant pharmacokinetics and evaluate target engagement. Cedirogant plasma concentrations and ex vivo interleukin 17A (IL-17A) concentrations from healthy participants and participants with moderate to severe psoriasis (PsO) were analyzed in a population pharmacokinetic and pharmacodynamic modeling framework to characterize cedirogant pharmacokinetics following single and multiple doses and assess ex vivo IL-17A inhibition in relation to cedirogant exposure. Cedirogant population pharmacokinetics were best described by a 2-compartment pharmacokinetic model with delayed absorption and an enzyme turnover compartment to describe cytochrome P450 3A autoinduction. The pharmacokinetics of cedirogant were comparable between healthy participants and participants with PsO. Cedirogant steady-state average and maximum plasma concentrations were predicted to be 7.56 and 11.8 mg/L, respectively, for participants with PsO for the 375 mg once-daily regimen on Day 14. The apparent clearance and apparent volume of distribution for cedirogant were estimated to be 24.5 L/day and 28.2 L, respectively. A direct maximum inhibition model adequately characterized the exposure-response relationship of cedirogant and ex vivo IL-17A inhibition, indicating no temporal delay between exposure and response with a saturable inhibition of IL-17A. Model-estimated half-maximal inhibitory concentration and maximum inhibition values for cedirogant inhibition of ex vivo IL-17A were 0.56 mg/L and 0.76, respectively. The established relationship between cedirogant exposure and biomarker effect supported dose selection for the Phase 2 dose-ranging study in patients with PsO.

Pharmacokinetics, Safety, and Tolerability of Cedirogant in Healthy Japanese and Chinese Adults

Cedirogant is an inverse agonist of retinoic acid-related orphan receptor gamma, thymus (RORγt) developed for treatment of psoriasis. This study aimed to characterize pharmacokinetics, pharmacodynamics, safety, and tolerability of cedirogant following a single oral dose in Japanese participants and multiple oral doses in Japanese and Chinese participants. The single doses evaluated in healthy Japanese participants were 75, 225, and 395 mg. The multiple doses evaluated in both healthy Japanese and Chinese participants was 375 mg once daily for 14 days. Cedirogant plasma exposure increased dose proportionally with administration of single doses. Maximum cedirogant plasma concentration was reached within a median time of 4-5 hours after dosing. The harmonic mean elimination half-life ranged from 19 to 25 hours. Cedirogant pharmacokinetics were similar between Japanese and Chinese participants. Compared with healthy Western participants in a cross-study analysis, steady-state cedirogant plasma exposure was 38%-73% higher in Japanese or Chinese participants. Ex vivo interleukin-17 inhibition increased in a dose-dependent manner and was maximized by 375 mg once-daily doses. The cedirogant regimens tested were generally well tolerated, and no new safety issues were identified. The results supported enrollment of Japanese and Chinese subjects in subsequent clinical trials for cedirogant.

Applications of Modeling and Simulation Approaches in Support of Drug Product Development of Oral Dosage Forms and Locally Acting Drug Products: a Symposium Summary

The number of modeling and simulation applications, including physiologically based pharmacokinetic (PBPK) models, physiologically based biopharmaceutics modeling (PBBM), and empirical models, has been constantly increasing along with the regulatory acceptance of these methodologies. While aiming at minimizing unnecessary human testing, these methodologies are used today to support the development and approval of novel drug products and generics. Modeling approaches are leveraged today for assessing drug-drug interaction, informing dose adjustments in renally or hepatically impaired patients, perform dose selection in pediatrics and pregnant women and diseased populations, and conduct biopharmaceutics-related assessments such as establish clinically relevant specifications for drug products and achieve quality assurance throughout the product life cycle. In the generics space, PBPK analyses are utilized toward virtual bioequivalence assessments within the scope of alternative bioequivalence approaches, product-specific guidance development, and food effect assessments among others. Case studies highlighting the evolving and expanding role of modeling and simulation approaches within the biopharmaceutics space were presented at the symposium titled "Model Informed Drug Development (MIDD): Role in Dose Selection, Vulnerable Populations, and Biowaivers - Chemical Entities" and Prologue "PBPK/PBBM to inform the Bioequivalence Safe Space, Food Effects, and pH-mediated DDIs" at the American Association of Pharmaceutical Scientists (AAPS) PharmSci 360 Annual Meeting in Boston, MA, on October 16-19, 2022, and are summarized here.

Upadacitinib Induction and Maintenance Therapy for Crohn's Disease

BACKGROUND

Upadacitinib, an oral selective Janus kinase (JAK) inhibitor, is under investigation for the treatment of Crohn's disease.

METHODS

In two phase 3 induction trials (U-EXCEL and U-EXCEED), we randomly assigned patients with moderate-to-severe Crohn's disease to receive 45 mg of upadacitinib or placebo (2:1 ratio) once daily for 12 weeks. Patients who had a clinical response to upadacitinib induction therapy were randomly assigned in the U-ENDURE maintenance trial to receive 15 mg of upadacitinib, 30 mg of upadacitinib, or placebo (1:1:1 ratio) once daily for 52 weeks. The primary end points for induction (week 12) and maintenance (week 52) were clinical remission (defined as a Crohn's Disease Activity Index score of <150 [range, 0 to 600, with higher scores indicating more severe disease activity]) and endoscopic response (defined as a decrease in the Simple Endoscopic Score for Crohn's Disease [SES-CD; range, 0 to 56, with higher scores indicating more severe disease] of >50% from baseline of the induction trial [or for patients with an SES-CD of 4 at baseline, a decrease of ≥2 points from baseline]).

RESULTS

A total of 526 patients underwent randomization in U-EXCEL, 495 in U-EXCEED, and 502 in U-ENDURE. A significantly higher percentage of patients who received 45-mg upadacitinib than those who received placebo had clinical remission (in U-EXCEL, 49.5% vs. 29.1%; in U-EXCEED, 38.9% vs. 21.1%) and an endoscopic response (in U-EXCEL, 45.5% vs. 13.1%; in U-EXCEED, 34.6% vs. 3.5%) (P<0.001 for all comparisons). At week 52 in U-ENDURE, a higher percentage of patients had clinical remission with 15-mg upadacitinib (37.3%) or 30-mg upadacitinib (47.6%) than with placebo (15.1%), and a higher percentage had an endoscopic response with 15-mg upadacitinib (27.6%) or 30-mg upadacitinib (40.1%) than with placebo (7.3%) (P<0.001 for all comparisons). Herpes zoster infections occurred more frequently in the 45-mg and 30-mg upadacitinib groups than in the respective placebo groups, and hepatic disorders and neutropenia were more frequent in the 30-mg upadacitinib group than in the other maintenance groups. Gastrointestinal perforations developed in 4 patients who received 45-mg upadacitinib and in 1 patient each who received 30-mg or 15-mg upadacitinib.

CONCLUSIONS

Upadacitinib induction and maintenance treatment was superior to placebo in patients with moderate-to-severe Crohn's disease. (Funded by AbbVie; U-EXCEL, U-EXCEED, and U-ENDURE ClinicalTrials.gov numbers, NCT03345849, NCT03345836, and NCT03345823.).

Use of Clinical Trial Simulations to Compare the Performance of Different Approaches for Population Analyses of Pediatric Pharmacokinetic Data

Adequate characterization of the pharmacokinetics of a drug in pediatrics is mainstay to pediatric development programs and is critical for accurate dose selection in pediatrics. Analysis approaches can impact estimation and characterization of pediatric pharmacokinetic parameters. Analyses were conducted to compare performance of different approaches for analysis of pediatric pharmacokinetic data in the presence of extensive data from adult studies. Simulated clinical trial datasets were generated encompassing different scenarios which might be encountered in pediatric drug development. For each scenario, 250 clinical trials were simulated and analyzed using each of the following approaches: 1) estimating pediatric parameters using only pediatric data, 2) fixing specific parameters to adult estimates and estimating the remaining pediatric parameters using only pediatric data, 3) estimating pediatric parameters using adult parameters as informative Bayesian priors, 4) estimating pediatric parameters using combined adult and pediatric datasets with exponents for weight and clearance estimated using adult and pediatric data 5) estimating pediatric parameters using combined adult and pediatric datasets with exponents for weight and clearance estimated using pediatric data only. Each analysis approach was evaluated for its success in estimation of true pediatric pharmacokinetic parameter values. Results demonstrated that analyzing pediatric data using a Bayesian approach generally performed best and had the lowest probability of significant bias in the estimated pediatric pharmacokinetic parameters amongst different scenarios evaluated. This clinical trial simulation framework can be used to inform the optimal approach for analyses of pediatric data for other pediatric drug development program scenarios beyond the cases evaluated in these analyses. This article is protected by copyright. All rights reserved.

Upadacitinib Population Pharmacokinetics and Exposure-Response Relationships in Ulcerative Colitis Patients

BACKGROUND AND OBJECTIVE

Upadacitinib, an oral selective and reversible Janus kinase (JAK) inhibitor, showed favorable efficacy and safety in patients with moderate-to-severe ulcerative colitis (UC). The objective was to characterize upadacitinib pharmacokinetics in UC patients across Phase 2b and 3 trials and evaluate the relationships between upadacitinib plasma exposures and key efficacy or safety endpoints.

METHODS

Population pharmacokinetics and exposure-response analyses were performed to characterize upadacitinib pharmacokinetics in UC patients and evaluate the relationships between plasma exposures and key efficacy or safety endpoints at the end of 8-week induction and 52-week maintenance periods. Data from 1234 UC patients from Phase 2 and 3 induction trials and 449 UC patients from a Phase 3 maintenance trial were used for these analyses. Additionally, data from patients with rheumatoid arthritis, atopic dermatitis, Crohn's disease, and healthy volunteers were used in the pharmacokinetics analysis. Quartile plots and logistic regression models were used to evaluate the exposure-response relationships across upadacitinib doses of 7.5-45 mg once daily (QD) for induction and 15-30 mg QD for maintenance.

RESULTS

Upadacitinib plasma exposures were dose-proportional in UC patients across the evaluated dose range. Upadacitinib pharmacokinetics in UC were consistent between the induction and maintenance periods, and with other patient populations. Upadacitinib plasma exposures associated with the 45 mg QD induction dose maximized efficacy for Week 8 clinical and endoscopic endpoints. Plasma exposures associated with upadacitinib 30 mg maintenance dose provided additional incremental benefit compared to 15 mg QD for Week 52 key clinical and endoscopic endpoints. No trends were observed in the evaluated safety events with increasing plasma exposures at the end of induction or maintenance periods.

CONCLUSION

These analyses supported selection of upadacitinib UC induction and maintenance doses.

TRIAL REGISTRATION

Data from studies NCT02819635 and NCT03653026 were included in these analyses.

Utility of Modeling and Simulation Approach to Support the Clinical Relevance of Dissolution Specifications: a Case Study from Upadacitinib Development

Dissolution specifications are often essential in assuring the quality and consistency of therapeutic benefits of drug lots released to the market as in vitro dissolution is often considered to be a surrogate for bioavailability. Despite the importance of demonstrating the clinical relevance of the dissolution specifications, it is often challenging to achieve this goal. In this case study, a modeling and simulation approach was utilized to support the clinical relevance of the dissolution specifications for upadacitinib extended-release tablets. A level A in vitro in vivo correlation was developed and utilized in predicting upadacitinib plasma exposures for formulations which correspond to the upper and lower dissolution limits. Exposure-response models for upadacitinib efficacy and safety in patients with moderate to severe rheumatoid arthritis (RA) were utilized to conduct clinical trial simulations to evaluate the efficacy and safety of formulations at the upper and lower dissolution boundaries. Each simulated clinical trial consisted of three treatment arms: (1) upadacitinib 15 mg QD using the target formulation, (2) upadacitinib 15 mg QD using a formulation at the lower dissolution boundary, and (3) upadacitinib 15 mg QD using a formulation at the upper dissolution boundary. Each simulated trial included 300 patients per arm and simulations were replicated 200 times. Results demonstrated that formulations at the lower and upper dissolution boundaries are predicted to have noninferior efficacy and comparable safety to the target 15 mg extended-release formulation. This approach was successfully utilized in demonstrating the clinical relevance of upadacitinib extended-release tablet dissolution specifications. Graphical Abstract.

Upadacitinib in patients from China, Brazil, and South Korea with rheumatoid arthritis and an inadequate response to conventional therapy

Aim

This study assessed the efficacy and safety of upadacitinib (UPA), in combination with conventional synthetic disease‐modifying antirheumatic drugs (csDMARDs), in Chinese, Brazilian, and South Korean patients with active rheumatoid arthritis (RA) and an inadequate response (IR) to csDMARDs.

Methods

Patients on stable csDMARDs were randomized (1:1) to once‐daily UPA 15 mg or matching placebo (PBO) for a 12‐week, double‐blind period. The primary endpoint was the proportion of patients achieving ≥20% improvement in American College of Rheumatology criteria (ACR20) at week 12.

Results

In total, 338 patients were randomized and treated, of whom 310 (91.7%) completed the double‐blind phase. The study met the primary endpoint of ACR20 at week 12 for UPA 15 mg vs PBO (71.6% vs 31.4%, P < .001), with a treatment difference observed as early as week 1. All ranked and other key secondary endpoints, including more stringent responses such as ACR50, ACR70 (≥50%/70% improvement in ACR criteria), and Disease Activity Score in 28 joints using C‐reactive protein <2.6, were met for UPA 15 mg vs PBO. The incidence of serious infections (2.4% vs 0.6%) and herpes zoster (HZ: 1.8% vs 0.6%) was higher with UPA 15 mg vs PBO. There was one case of venous thromboembolism reported in the UPA group.

Conclusion

UPA 15 mg in combination with csDMARDs demonstrated clinical and functional improvement and an acceptable safety profile over 12 weeks among patients from China, Brazil, and South Korea who had moderately to severely active RA and an IR to csDMARDs.

Upadacitinib pharmacokinetics and exposure-response analyses of efficacy and safety in psoriatic arthritis patients - Analyses of phase III clinical trials

Upadacitinib is an oral Janus kinase inhibitor approved for the treatment of rheumatoid arthritis (RA) and recently approved by the European Medicines Agency for the treatment of psoriatic arthritis (PsA). The efficacy and safety profile of upadacitinib in PsA have been established in the SELECT‐PsA program in two global phase III studies, which evaluated upadacitinib 15 and 30 mg q.d. The analyses described here characterized upadacitinib pharmacokinetics and exposure‐response relationships for efficacy and safety endpoints using data from the SELECT‐PsA studies. Upadacitinib pharmacokinetics in patients with PsA were characterized through a Bayesian population analysis approach and were comparable to pharmacokinetics in patients with RA. Exposure‐response relationships for key efficacy and safety endpoints were characterized using data from 1916 patients with PsA. The percentage of patients achieving efficacy endpoints at week 12 (American College of Rheumatology [ACR]50 and ACR70), 16 and 24 (sIGA0/1) increased with increasing upadacitinib average plasma concentration over a dosing interval, whereas no clear exposure‐response trend was observed for ACR20 at week 12 or ACR20/50/70 at week 24 within the range of plasma exposures evaluated in the phase III PsA studies. No clear trends for exposure‐response relationships were identified for experiencing pneumonia, herpes zoster infection, hemoglobin less than 8 g/dl, lymphopenia (grade ≥ 3), or neutropenia (grade ≥ 3) after 24 weeks of treatment. Shallow relationships with plasma exposures were observed for serious infections and hemoglobin decrease greater than 2 g/dl from baseline at week 24. Based on exposure‐response analyses, the upadacitinib 15 mg q.d. regimen is predicted to achieve robust efficacy in patients with PsA and to be associated with limited incidences of reductions in hemoglobin or occurrence of serious infections.

Effect of Upadacitinib on the Pharmacokinetics of Rosuvastatin or Atorvastatin in Healthy Subjects

This phase 1, 2‐part, 2‐period, open‐label, drug‐drug interaction study evaluated the potential for pharmacokinetic interactions between upadacitinib and rosuvastatin, an organic anion transporting polypeptide (OATP) 1B1 and breast cancer resistance protein substrate, or atorvastatin, a cytochrome P450 3A, OATP1B1, and OATP1B3 substrate, in 36 healthy volunteers. During period 1, a single dose of rosuvastatin (5 mg; part 1) or atorvastatin (10 mg; part 2) was administered on day 1, followed by a washout period of 5 days. During period 2, once‐daily doses of upadacitinib extended‐release (30 mg) were administered on days 1 to 10, and a single dose of rosuvastatin (5 mg; part 1) or atorvastatin (10 mg; part 2) was administered 1 hour after the upadacitinib dose on day 7. Serial blood samples were collected for assays of drug concentrations. In Part 1, rosuvastatin maximum observed plasma concentration (C_max) and area under the plasma concentration–time curve from time 0 to infinity (AUC_inf) were 23% and 33% lower, respectively, when administered with upadacitinib relative to when administered alone. In part 2, atorvastatin C_max and AUC_inf was 11% and 23% lower, respectively, when administered with upadacitinib relative to when administered alone. The C_max and AUC_inf of the active metabolite ortho‐hydroxyatorvastatin remained unchanged. Administration of a single 5‐mg dose of rosuvastatin or a single 10‐mg dose of atorvastatin had no relevant effect on upadacitinib C_max or area under the plasma concentration–time curve. These results demonstrated that upadacitinib has no clinically relevant effect on the pharmacokinetics of rosuvastatin and atorvastatin or on substrates transported by OATP1B or breast cancer resistance protein.

Coproporphyrin I Can Serve as an Endogenous Biomarker for OATP1B1 Inhibition: Assessment Using a Glecaprevir/Pibrentasvir Clinical Study

Organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 are involved in the disposition of a variety of commonly prescribed drugs. The evaluation of OATP1B1/1B3 inhibition potential by investigational drugs is of interest during clinical drug development due to various adverse events associated with increased exposures of their substrates. Regulatory guidance documents on the in vitro assessment of OATP1B1/1B3 inhibition potential are conservative with up to a third of predictions resulting in false positives. This work investigated the utility of OATP1B1/1B3 endogenous biomarkers, coproporphyrin (CP)‐I and CP‐III, to assess clinical inhibition of OATP1B1/1B3 and potentially eliminate the need for prospective clinical drug‐drug interaction (DDI) studies. Correlations between CP‐I exposures and various OATP1B1 static DDI predictions were also evaluated. Glecaprevir/pibrentasvir (GLE/PIB) 300/120 mg fixed‐dose combination is known to cause clinical inhibition of OATP1B1/1B3. In a clinical study evaluating the relative bioavailability of various formulations of GLE/PIB regimen, CP‐I peak plasma concentration (C_max) ratio and 0–16‐hour area under the concentration‐time curve (AUC_0–16) ratio relative to baseline increased with increasing GLE exposures, whereas there was a modest correlation between GLE exposure and CP‐III C_max ratio but no correlation with CP‐III AUC_0–16 ratio. This suggests that CP‐I is superior to CP‐III as an endogenous biomarker for evaluation of OATP1B1 inhibition. There was a significant correlation between CP‐I and GLE C_max (R² = 0.65; P < 0.001) across individual subjects. Correlation analysis between GLE OATP1B1 R values and CP‐I exposures (C_max ratio and AUC_0–16 ratio) suggests that an R value of > 3 can predict a biologically meaningful inhibition of OATP1B1 when the inhibitor clinical pharmacokinetic parameters are available.

Therapeutic Protein Drug Interaction Potential in Subjects With Psoriasis: An Assessment Based on Population Pharmacokinetic Analyses of Sensitive Cytochrome P450 Probe Substrates

Elevated cytokine levels in inflammatory diseases are associated with downregulation of certain cytochrome P450 (CYP) enzymes. Upon treatment with some cytokine-targeting therapeutic proteins, the CYP enzymes levels may be restored resulting in therapeutic protein-mediated drug interactions (TP-DI). These analyses characterized the worst-case scenario for CYP1A2, 2C9, and 3A-based TP-DI potential in patients with psoriasis by comparing the pharmacokinetics of probe substrates between healthy volunteers and subjects with moderate to severe psoriasis. Data for the CYP probe substrates midazolam (CYP3A), caffeine (CYP1A2), and S-warfarin (CYP2C9) from 7 drug interaction studies (1 in patients with psoriasis and 6 in healthy subjects) were pooled to develop a population pharmacokinetics model for each substrate. A 2-compartment model with absorption lag time for midazolam, a 1-compartment model with 5 transit absorption compartments for caffeine, and a 3-compartment model with absorption lag time for S-warfarin best described the observed data. Apparent oral clearance and relative bioavailability for caffeine and S-warfarin were not significantly different between the subject populations. Psoriasis patients were estimated to have 17% lower midazolam oral bioavailability than healthy volunteers. Compounded with other covariate effects, the ratio of median post hoc area under the plasma concentration-time estimates in subjects with psoriasis relative to healthy subjects was 0.96, 1.13, and 0.65 for midazolam, caffeine, and S-warfarin, respectively. Therefore, inflammation in psoriasis had no relevant effect on reducing CYP1A2, 2C9, and 3A activities in vivo and no significant TP-DIs mediated through these enzymes are expected in patients with psoriasis. This approach can potentially be used in lieu of dedicated TP-DI studies to identify TP-DI risks within a disease area.

Efficacy and Safety of Upadacitinib Monotherapy in Methotrexate-Naive Patients With Moderately-to-Severely Active Rheumatoid Arthritis (SELECT-EARLY): A Multicenter, Multi-Country, Randomized, Double-Blind, Active Comparator-Controlled Trial

OBJECTIVE

The SELECT-EARLY trial was undertaken to study the effect of upadacitinib, an oral, reversible Janus kinase 1-selective inhibitor, as monotherapy in patients with predominantly early rheumatoid arthritis who were naive for or had limited exposure to methotrexate (MTX).

METHODS

Patients (n = 947) were randomized 1:1:1 to receive once-daily doses of upadacitinib 15 mg or 30 mg or weekly MTX (7.5-20 mg/week) for 24 weeks. The primary end points were the proportion of patients who met the American College of Rheumatology 50% (ACR50) improvement criteria at week 12, and the proportion in whom a Disease Activity Score in 28 joints using the C-reactive protein level (DAS28-CRP) of <2.6 was achieved at week 24. Data are presented through week 24.

RESULTS

At baseline, the median disease duration was 0.5 years (range 0-44 years). A total of 840 patients (89%) completed 24 weeks of treatment. The study met both primary end points for upadacitinib 15 mg and 30 mg versus MTX (ACR50 was achieved at week 12 in 52% and 56% of patients, respectively, versus 28% [P < 0.001], and DAS28-CRP <2.6 was achieved at week 24 in 48% and 50% of patients, respectively, versus 19% [P < 0.001]). Statistically significant and clinically meaningful improvements in multiple patient-reported outcomes (PROs) were recorded for both upadacitinib doses versus MTX. Overall, 88% of patients receiving upadacitinib 15 mg and 89% of patients receiving 30 mg, respectively, had no radiographic progression (modified total Sharp score ≤0) compared to 78% of those receiving MTX (P < 0.01). Through week 24, the frequency of treatment-emergent adverse events was similar between the MTX arm (65%) and upadacitinib 15 mg arm (64%), but was slightly higher in the upadacitinib 30 mg arm (71%). Six deaths were reported (2 in the upadacitinib 15 mg arm, 3 in the upadacitinib 30 mg arm, and 1 in the MTX arm).

CONCLUSION

Our findings indicate that patients receiving either dose of upadacitinib monotherapy experienced significant improvements in clinical, radiographic, and PROs compared to patients receiving MTX.

Efficacy and Safety of Upadacitinib in a Randomized Trial of Patients With Crohn's Disease

BACKGROUND & AIMS

We evaluated the efficacy and safety of upadacitinib, an oral selective Janus kinase 1 inhibitor, in a randomized trial of patients with Crohn's disease (CD).

METHODS

We performed a double-blind, phase 2 trial in adults with moderate to severe CD and inadequate response or intolerance to immunosuppressants or tumor necrosis factor antagonists. Patients were randomly assigned (1:1:1:1:1:1) to groups given placebo; or 3 mg, 6 mg, 12 mg, or 24 mg upadacitinib twice daily; or 24 mg upadacitinib once daily and were evaluated by ileocolonoscopy at weeks 12 or 16 of the induction period. Patients who completed week 16 were re-randomized to a 36-week period of maintenance therapy with upadacitinib. The primary endpoints were clinical remission at week 16 and endoscopic remission at week 12 or 16 using the multiple comparison procedure and modeling and the Cochran-Mantel-Haenszel test, with a 2-sided level of 10%.

RESULTS

Among the 220 patients in the study, clinical remission was achieved by 13% of patients receiving 3 mg upadacitinib, 27% of patients receiving 6 mg upadacitinib (P < .1 vs placebo), 11% of patients receiving 12 mg upadacitinib, and 22% of patients receiving 24 mg upadacitinib twice daily, and by 14% of patients receiving 24 mg upadacitinib once daily, vs 11% of patients receiving placebo. Endoscopic remission was achieved by 10% (P < .1 vs placebo), 8%, 8% (P < .1 vs placebo), 22% (P < .01 vs placebo), and 14% (P < .05 vs placebo) of patients receiving upadacitinib, respectively, vs none of the patients receiving placebo. Endoscopic but not clinical remission increased with dose during the induction period. Efficacy was maintained for most endpoints through week 52. During the induction period, patients in the upadacitinib groups had higher incidences of infections and serious infections vs placebo. Patients in the twice-daily 12 mg and 24 mg upadacitinib groups had significant increases in total, high-density lipoprotein, and low-density lipoprotein cholesterol levels compared with patients in the placebo group.

CONCLUSIONS

In a phase 2 trial of patients with CD, upadacitinib induced endoscopic remission in a significant proportion of patients compared with placebo. Upadacitinib's benefit/risk profile supports further development for treatment of CD. (Clinicaltrials.gov, Number: NCT02365649).

Clinical Pharmacokinetics of Upadacitinib: Review of Data Relevant to the Rheumatoid Arthritis Indication

Upadacitinib is a Janus kinase 1 inhibitor developed for treatment of moderate to severe rheumatoid arthritis (RA) and was recently approved by the US Food and Drug Administration for this indication in adults who have had an inadequate response or intolerance to methotrexate. Upadacitinib is currently under regulatory review by other agencies around the world. Ongoing trials are investigating the use of upadacitinib in other inflammatory autoimmune diseases. In this article, we review the clinical pharmacokinetic data available to date for upadacitinib that supported the clinical development program in RA and ultimately regulatory applications for upadacitinib in treatment of patients with moderate to severe RA.

Exposure-Response Analyses of Upadacitinib Efficacy and Safety in Phase II and III Studies to Support Benefit-Risk Assessment in Rheumatoid Arthritis

Exposure–response analyses of upadacitinib (UPA) key efficacy and safety end points (3,685 and 4,577 subjects for efficacy and safety, respectively) using data from phase II and phase III rheumatoid arthritis (RA) studies were conducted to support benefit–risk assessment. Percentage of subjects achieving American College of Rheumatology (ACR)20/50/70, disease activity score 28 (C‐reactive protein) (DAS28‐CRP) ≤ 3.2, and DAS28‐CRP < 2.6 increased with increasing UPA plasma exposures. With the small number of observed safety events, no clear trends for exposure–response relationships were identified for pneumonia, herpes zoster infection, changes in platelet count, lymphopenia (Grade ≥ 4), or neutropenia (Grade ≥ 3) up to Week 26. Shallow exposure–response relationships were observed for > 2 g/dL decrease in hemoglobin, lymphopenia Grade ≥ 3 at Week 12/14, and serious infections at Week 24/26. Exposure–efficacy analyses demonstrate that UPA 15 mg q.d. (once daily) dose provided the optimal benefit–risk in RA through maximizing efficacy with only small incremental benefit with 30 mg q.d.; and with consistency across RA subpopulations and with UPA monotherapy or combination with conventional synthetic disease‐modifying antirheumatic drugs.

Exposure-Response Analyses for Upadacitinib Efficacy and Safety in the Crohn's Disease CELEST Study and Bridging to the Extended-Release Formulation

Upadacitinib plasma concentrations, efficacy, and safety data from 216 subjects with moderate‐to‐severe active Crohn's disease (CD) from the 16‐week induction period of the CELEST study were analyzed to characterize upadacitinib exposure–response relationships in CD. Subjects in CELEST received either placebo or upadacitinib (3, 6, 12, 24 mg b.i.d. or 24 mg q.d.). Exposure–response models were developed and utilized to simulate efficacy of induction doses of the immediate‐release (IR) and extended‐release (ER) formulations. Upadacitinib exposures associated with 18–24 mg b.i.d. (IR formulation) or 45–60 mg q.d. (ER formulation) are estimated to have greater efficacy during 12‐week induction in patients with CD compared with lower doses. No exposure–response relations were observed with decreases in hemoglobin or lymphocytes at week 16 or with herpes zoster infections, pneumonia, or serious infections during 16 weeks of treatment in this study. These analyses informed the selection of upadacitinib induction dose for phase III studies in CD.

Development of In Vitro-In Vivo Correlation for Upadacitinib Extended-Release Tablet Formulation

Upadacitinib is a selective Janus Kinase 1 inhibitor which is being developed for the treatment of several inflammatory diseases including rheumatoid arthritis. Upadacitinib was evaluated in Phase 3 studies as an oral extended-release (ER) formulation administered once daily. The purpose of this study was to develop a level A in vitro-in vivo correlation (IVIVC) for upadacitinib ER formulation. The pharmacokinetics of four upadacitinib extended-release formulations with different in vitro release characteristics and an immediate-release capsule formulation of upadacitinib were evaluated in 20 healthy subjects in a single-dose, randomized, crossover study. In vivo pharmacokinetic data and in vitro dissolution data (USP Dissolution Apparatus 1; pH 6.8; 100 rpm) were used to establish a level A IVIVC. Three formulations were used to establish the IVIVC, and the fourth formulation was used for external validation. A non-linear IVIVC best described the relationship between upadacitinib in vitro dissolution and in vivo absorption profiles. The absolute percent prediction errors (%PE) for upadacitinib Cmax and AUC were less than 10% for all three formulations used to establish the IVIVC, as well as for the %PE for the external validation formulation and the overall mean internal validation. Model was cross-validated using the leave-one-out approach; all evaluated cross-validation runs met the regulatory acceptance criteria. A level A IVIVC was successfully developed and validated for upadacitinib ER formulation, which meets the FDA and EMA regulatory validation criteria and can be used as surrogate for in vivo bioequivalence.

Population Pharmacokinetics of Upadacitinib in Healthy Subjects and Subjects with Rheumatoid Arthritis: Analyses of Phase I and II Clinical Trials

Background and Objectives

Upadacitinib is a janus kinase (JAK) 1 inhibitor being developed for the treatment of rheumatoid arthritis (RA) and other inflammatory diseases. This work characterized upadacitinib population pharmacokinetics in healthy subjects and RA patients and the effects of covariates on upadacitinib exposure.

Methods

Upadacitinib plasma concentrations (n = 6399) from 107 healthy subjects and 466 RA patients from three phase I and two 12-week RA phase IIb trials (1–48 mg immediate-release doses across studies) were analyzed using non-linear mixed-effects modeling. The models were qualified using bootstrap and stochastic simulations.

Results

A two-compartment model with first-order absorption and elimination described upadacitinib pharmacokinetics. Estimates (95% bootstrap confidence interval) for upadacitinib oral clearance, steady-state volume of distribution, absorption lag time, and mean absorption time were 39.7 (37.8–41.5) L/h, 210 (196–231) L, 0.48 (0.47–0.49) h, and 0.08 (0.04–0.12) h, respectively, for a typical healthy male. Matching on other covariates, a 16 and 32% higher upadacitinib area under the concentration–time curve (AUC) was estimated for females relative to males, and for subjects with RA relative to healthy volunteers, respectively. Subjects with RA with mild or moderate renal impairment were estimated to have 16 and 32% higher upadacitinib AUC, respectively, compared with subjects with RA with normal renal function. Upadacitinib clearance was not correlated with body weight.

Conclusions

Upadacitinib pharmacokinetics follow dose-proportional, bi-exponential disposition. A slightly lower upadacitinib clearance is estimated in subjects with RA than in healthy volunteers, consistent with observations for other JAK inhibitors. Other covariates (weight, sex, mild or moderate renal impairment) are not associated with clinically relevant effects on upadacitinib exposure.

Trial Registration

ClinicalTrials.gov (https://clinicaltrials.gov/) identifiers: NCT01741493, NCT02066389, and NCT01960855.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-017-0605-6) contains supplementary material, which is available to authorized users.

Population Pharmacokinetics of Upadacitinib Using the Immediate-Release and Extended-Release Formulations in Healthy Subjects and Subjects with Rheumatoid Arthritis: Analyses of Phase I-III Clinical Trials

BACKGROUND AND OBJECTIVES

Upadacitinib is a selective Janus kinase (JAK) 1 inhibitor being developed as an orally administered treatment for patients with moderate to severe rheumatoid arthritis (RA) and other autoimmune disorders. These analyses characterized the population pharmacokinetics of upadacitinib across phase I-III clinical trials using data for immediate-release (IR) and extended-release (ER) formulations.

METHODS

Pharmacokinetic data from 4170 subjects taking IR doses of 1-48 mg and ER doses of 7.5-30 mg across 12 studies spanning phase I-III clinical trials, with a total of 29,372 upadacitinib plasma concentrations, were analyzed using non-linear mixed-effects modeling. The model was evaluated using bootstrap analyses and visual predictive checks.

RESULTS

A two-compartment model with first-order absorption with lag time for the IR formulation, mixed zero- and first-order absorption with lag time for the ER formulation, and linear elimination, adequately described upadacitinib plasma concentration-time profiles. Population estimates of upadacitinib apparent oral clearance and steady-state volume of distribution in healthy volunteers for the ER formulation were 53.7 L/h and 294 L, respectively. The relative bioavailability of the ER formulation compared with the IR formulation was estimated to be 76.2%. Statistically significant covariates were patient population (RA subjects vs. healthy subjects), creatinine clearance, and baseline bodyweight on apparent clearance (CL/F) and bodyweight on volume of distribution of the central compartment (Vc/F). The intersubject variability for upadacitinib CL/F and Vc/F were estimated to be 21% and 24%, respectively, in the phase I studies, and 37% and 53%, respectively, in the phase II/III studies. Upadacitinib area under the concentration-time curve (AUC) was estimated to be only 5% higher or lower for RA patients who were < 60 or > 100 kg, respectively, relative to subjects with a bodyweight of 60-100 kg. RA subjects with mild or moderate renal impairment had 13% and 26% higher AUC, respectively, compared with RA subjects with normal renal function. Sex, race, concomitant use of pH-modifying drugs, moderate cytochrome P450 3A inhibitors, or methotrexate use had no effect on upadacitinib exposure.

CONCLUSIONS

A robust population pharmacokinetic model was developed for upadacitinib using a large dataset from phase I-III clinical trials in healthy volunteers and subjects with RA. None of the identified covariates had a clinically meaningful effect on upadacitinib exposures. The model is appropriate to use for simulations and to evaluate the exposure-response relationship of upadacitinib.

Characterization of the Effect of Renal Impairment on Upadacitinib Pharmacokinetics

Upadacitinib is a novel selective Janus kinase 1 inhibitor developed for treatment of rheumatoid arthritis and other autoimmune diseases. The objective of this study was to assess the pharmacokinetics and safety of a single upadacitinib dose in subjects with normal renal function and in subjects with renal impairment. A total of 24 subjects between the ages of 18 and 75 years were assigned to 1 of 4 renal function groups based on estimated glomerular filtration rate (normal, mild, moderate, severe; N = 6/group). A single 15-mg dose of upadacitinib extended-release formulation was administered under fasting conditions. Serial plasma and urine samples were assayed to evaluate the effect of renal impairment on upadacitinib exposure through regression analysis and analysis of covariance. The primary analysis was the regression analysis of upadacitinib exposures versus estimated glomerular filtration rate. The point estimates for upadacitinib plasma exposure ratios (90% confidence interval [CI]) in subjects with mild, moderate, and severe renal impairment were 1.18 (90%CI, 1.06-1.32), 1.33 (90%CI, 1.11-1.59), and 1.44 (90%CI, 1.14-1.82) for area under the plasma concentration-time curve and 1.06 (90%CI, 0.92-1.23), 1.11 (90%CI, 0.88-1.40), and 1.14 (90%CI, 0.84-1.56) for maximum observed plasma concentration, respectively, relative to subjects with normal renal function based on the regression analysis. The analysis of covariance categorical analysis provided consistent results. Upadacitinib was well tolerated by all subjects, and no safety issues were identified in subjects with renal impairment. Renal impairment has a limited effect on upadacitinib pharmacokinetics. This is in agreement with the known limited role of urinary excretion in upadacitinib elimination. Based on the limited impact on exposure, no dose adjustment is necessary for upadacitinib in subjects with impaired renal function.

The JAK1 Inhibitor Upadacitinib Has No Effect on the Pharmacokinetics of Levonorgestrel and Ethinylestradiol: A Study in Healthy Female Subjects

Upadacitinib is a novel selective oral Janus kinase 1 (JAK) inhibitor being developed for treatment of several inflammatory diseases. Oral contraceptives are anticipated to be a common concomitant medication in the target patient populations. This study was designed to evaluate the effect of multiple doses of upadacitinib on the pharmacokinetics of ethinylestradiol and levonorgestrel in healthy female subjects. This phase I, single‐center, open‐label, 2‐period crossover study evaluated the effect of multiple doses of 30 mg once daily extended‐release upadacitinib on the pharmacokinetics of a single oral dose of ethinylestradiol/levonorgestrel (0.03/0.15 mg; administered alone in period 1 and on day 12 of a 14‐day regimen of upadacitinib in period 2) in 22 healthy female subjects. The ratios (90% confidence intervals) for maximum plasma concentration and area under the plasma drug concentration–time curve from time zero to infinity following administration of ethinylestradiol/levonorgestrel with upadacitinib compared with administration of ethinylestradiol/ levonorgestrel alone were 0.96 (0.89–1.02) and 1.1 (1.04–1.19), respectively, for ethinylestradiol, and 0.96 (0.87–1.06) and 0.96 (0.85–1.07), respectively, for levonorgestrel. The harmonic mean terminal half‐life for ethinylestradiol (7.7 vs 7.0 hours) and levonorgestrel (37.1 vs 33.1 hours) was similar in the presence and absence of upadacitinib. Ethinylestradiol and levonorgestrel were bioequivalent in the presence and absence of upadacitinib. Therefore, upadacitinib can be administered concomitantly with oral contraceptives containing ethinylestradiol or levonorgestrel.

Safety and efficacy of upadacitinib in patients with active rheumatoid arthritis refractory to biologic disease-modifying anti-rheumatic drugs (SELECT-BEYOND): a double-blind, randomised controlled phase 3 trial

BACKGROUND

Phase 2 studies with upadacitinib, a selective Janus kinase 1 (JAK1) inhibitor, have shown safety and efficacy in the treatment of patients with active rheumatoid arthritis. We did this study to further assess the safety and efficacy of upadacitinib in patients with an inadequate response to biologic disease-modifying anti-rheumatic drugs (bDMARDs).

METHODS

We did this double-blind, randomised controlled phase 3 trial at 153 sites in 26 countries. Patients were aged 18 years or older, had active rheumatoid arthritis and previous inadequate response or intolerance to bDMARDs, and were receiving concomitant background conventional synthetic DMARDS (csDMARDs). We randomly assigned patients (2:2:1:1) by interactive response technology to receive once-daily oral extended-release upadacitinib 15 mg or 30 mg or placebo for 12 weeks, followed by upadacitinib 15 mg or 30 mg from week 12 onwards. The two separate primary endpoints were the proportions of patients achieving a 20% improvement in American College of Rheumatology criteria (ACR20) at week 12 and the proportion of patients achieving a 28-joint disease activity score using C-reactive protein (DAS28[CRP]) of 3·2 or less at week 12. Efficacy and safety analyses were done in the modified intention-to-treat population of all patients who received at least one dose of study drug. Data are presented up to week 24 of this ongoing study. The trial is registered with ClinicalTrials.gov (NCT02706847).

FINDINGS

Between March 15, 2016, and Jan 10, 2017, 499 patients were randomly assigned (n=165 upadacitinib 15 mg; n=165 upadacitinib 30 mg; n=85 placebo then upadacitinib 15 mg; and n=84 placebo then upadacitinib 30 mg) and one patient was withdrawn from the 15 mg upadacitinib group before the start of study treatment. Mean disease duration was 13·2 years (SD 9·5); 235 (47%) of 498 patients had received one previous bDMARD, 137 (28%) had received two, and 125 (25%) had received at least three; 451 (91%) patients completed treatment up to week 12 and 419 (84%) patients completed treatment up to week 24. At week 12, ACR20 was achieved by 106 (65%; 95% CI 57-72) of 164 patients receiving upadacitinib 15 mg and 93 (56%; 49-64) of 165 patients receiving upadacitinib 30 mg compared with 48 (28%; 22-35) of 169 patients receiving placebo (p<0·0001 for each dose vs placebo). DAS28(CRP) of 3·2 or less was achieved by 71 (43%; 95% CI 36-51) of 164 patients receiving upadacitinib 15 mg and 70 (42%; 35-50) of 165 patients receiving upadacitinib 30 mg versus 24 (14%; 9-20) of 169 patients receiving placebo (p<0·0001 for each dose vs placebo). Up to week 12, overall numbers of patients with adverse events were similar for the placebo group (95 [56%] of 169) and the upadacitinib 15 mg group (91 [55%] of 164), but higher in the upadacitinib 30 mg group (111 [67%] of 165). At week 12, the most common adverse events occurring in at least 5% of patients in any treatment group were upper respiratory tract infection (13 [8%] of 169 in the placebo group; 13 [8%] of 164 in the upadacitinib 15 mg group; ten [6%] of 165 in the upadacitinib 30 mg group), nasopharyngitis (11 [7%]; seven [4%]; nine [5%]), urinary tract infection (ten [6%]; 15 [9%]; nine [5%]), and worsening of rheumatoid arthritis (ten [6%]; four [2%]; six [4%]). The number of patients with serious adverse events was higher in the upadacitinib 30 mg group (12 [7%]) than in the upadacitinib 15 mg group (eight [5%]); no serious adverse events were reported in patients receiving placebo. More patients in the upadacitinib 30 mg group had serious infections, herpes zoster, and adverse events leading to discontinuation than in the upadacitinib 15 mg and placebo groups. During the placebo-controlled phase of the study, one case of pulmonary embolism, three malignancies, one major adverse cardiovascular event, and one death were reported in patients receiving upadacitinib; none were reported in patients receiving placebo.

INTERPRETATION

Both doses of upadacitinib led to rapid and significant improvements compared with placebo over 12 weeks in patients with refractory rheumatoid arthritis.

FUNDING

AbbVie Inc.

Pharmacokinetics of Upadacitinib With the Clinical Regimens of the Extended-Release Formulation Utilized in Rheumatoid Arthritis Phase 3 Trials

Upadacitinib is a Janus kinase 1 inhibitor under development for the treatment of several inflammatory disorders including rheumatoid arthritis (RA). Upadacitinib was administered in the phase 2 RA trials primarily as twice-daily regimens of an immediate-release (IR) formulation. The upadacitinib extended-release (ER) formulation was developed to enable once-daily dosing. In the present study, upadacitinib pharmacokinetics were characterized after the administration of single and multiple once-daily doses of the ER formulation in healthy subjects relative to single and multiple twice-daily doses of the IR formulation. Increase in upadacitinib exposure was dose-proportional over the evaluated 15- to 30-mg ER dose range. Single 15- and 30-mg ER doses provided equivalent AUC_0-inf compared with single 12- and 24-mg IR doses, respectively. A high-fat breakfast increased upadacitinib ER C_max and AUC_0-inf by only 20% and 17%, respectively, relative to fasting conditions. The median time to peak plasma concentrations was 2 to 4 hours for the ER formulation, and steady state was achieved by day 4 of once-daily dosing. Doses of 15 and 30 mg once daily using the ER formulation provided equivalent AUC_0-24 , comparable C_max and C_min , and a fluctuation index over a 24-hour period at steady state similar to 6 and 12 mg twice daily, respectively, using the IR formulation. These results supported the use of upadacitinib 15- and 30-mg doses of the ER formulation in the phase 3 trials in RA.

Use of Early Clinical Trial Data to Support Thorough QT Study Waiver for Upadacitinib and Utility of Food Effect to Demonstrate ECG Assay Sensitivity

Exposure–response analyses of QT data from early‐stage clinical studies represent a valuable tool to assess the QT prolongation potential for drugs in development in lieu of standalone thorough QT (TQT) studies. However, demonstrating adequate electrocardiogram assay sensitivity can be challenging in the absence of a positive pharmacological control. Upadacitinib is a Janus kinase 1 inhibitor currently being evaluated in phase III rheumatoid arthritis trials. Exposure–response analyses to evaluate the QT prolongation potential for upadacitinib from phase I trials and the utility of the effect of food on QTcF to demonstrate ECG assay sensitivity are presented. The analyses demonstrated no effect of upadacitinib on QT interval and confirmed the sensitivity of the ECG assay to detect the small QT shortening effect caused by food. Lack of bias from manual ECG adjudication was also demonstrated. These analyses supported requesting a waiver for the regulatory requirement for a dedicated thorough QT study for upadacitinib.

Assessment of effect of CYP3A inhibition, CYP induction, OATP1B inhibition, and high-fat meal on pharmacokinetics of the JAK1 inhibitor upadacitinib

AIMS

Upadacitinib (ABT-494) is a selective Janus kinase 1 inhibitor being developed for treatment of auto-immune inflammatory disorders. This work evaluated effects of high-fat meal, cytochrome P450 (CYP) 3A inhibition, CYP induction, and organic anion transporting polypeptide (OATP) 1B inhibition on upadacitinib pharmacokinetics.

METHODS

Two Phase 1 evaluations were conducted, each in 12 healthy subjects. In Study 1, using a randomized, two-sequence crossover design, a 3 mg dose of upadacitinib (immediate-release capsules) was administered alone under fasting conditions, after high-fat meal, or on Day 4 of a 6-day regimen of 400 mg once-daily ketoconazole. In Study 2, a 12 mg upadacitinib dose was administered alone, with the first, and with the eighth dose of a 9-day regimen of rifampin 600 mg once daily. Upadacitinib plasma concentrations were characterized.

RESULTS

Administration of upadacitinib immediate-release capsules after a high-fat meal decreased upadacitinib C_max by 23% and had no impact on upadacitinib AUC relative to the fasting conditions. Ketoconazole (strong CYP3A inhibitor) increased upadacitinib C_max and AUC by 70% and 75%, respectively. Multiple doses of rifampin (broad CYP inducer) decreased upadacitinib C_max and AUC by approximately 50% and 60%, respectively. A single dose of rifampin (also an OATP1B inhibitor) had no effect on upadacitinib AUC. Upadacitinib was well tolerated when co-administered with ketoconazole, rifampin, or after a high-fat meal.

CONCLUSIONS

Strong CYP3A inhibition and broad CYP induction result in a weak and moderate effect, respectively, on upadacitinib exposures. OATP1B inhibition and administration of upadacitinib immediate-release formulation with food does not impact upadacitinib exposure.

Jejunal Infusion of levodopa-carbidopa intestinal gel versus oral administration of levodopa-carbidopa tablets in japanese subjects with advanced Parkinson's disease: pharmacokinetics and pilot efficacy and safety

Background and Objective

Oral levodopa-carbidopa (LC-oral) treatment in advanced Parkinson’s disease (PD) is associated with motor complications due to large fluctuations in levodopa plasma concentrations. Levodopa–carbidopa intestinal gel (LCIG) provides individualized continuous levodopa–carbidopa delivery through intrajejunal infusion. This study evaluated the pharmacokinetics, safety, and efficacy of LCIG relative to LC-oral in Japanese subjects with advanced PD.

Methods

Subjects with advanced PD were converted from their anti-PD medications to individually optimized doses of LC-oral (10:1 levodopa:carbidopa ratio) for 28 days (baseline; period 1) followed by switching to intrajejunal infusion of LCIG (4:1 ratio) for 21 days (period 2). Pharmacokinetics, adverse events (AEs), and efficacy were assessed.

Results

Eight patients were enrolled. Six received LCIG and four reported at least one AE [most common: fall (33.3 %), dyskinesia (33.3 %)]; one discontinued due to an AE. The average daily dose was 1230/123 and 1370/342 mg levodopa/carbidopa for LC-oral and LCIG, respectively, at the end of each period. The degree of fluctuation and intra-subject variability of levodopa plasma concentrations were 5.5- and 4-fold lower, respectively, with LCIG than with LC-oral. Levodopa bioavailability was 99 % for LCIG relative to LC-oral. Compared with baseline, LCIG decreased “Off” time (2.68 h, P = 0.002) and increased “On” time without troublesome dyskinesia (2.35 h, P = 0.006) in the PD Diary^©. With the small sample size, no statistically significant changes were seen on other efficacy endpoints.

Conclusions

In Japanese subjects with advanced PD, LCIG resulted in an improved pharmacokinetic profile that appeared to be associated with reduced motor complications compared with LC-oral. These results extend previous findings in mainly Caucasian populations.

Inhibitory effects of commonly used herbal extracts on UDP-glucuronosyltransferase 1A4, 1A6, and 1A9 enzyme activities

The aim of this study was to investigate the effect of commonly used botanicals on UDP-glucuronosyltransferase (UGT) 1A4, UGT1A6, and UGT1A9 activities in human liver microsomes. The extracts screened were black cohosh, cranberry, echinacea, garlic, ginkgo, ginseng, milk thistle, saw palmetto, and valerian in addition to the green tea catechin epigallocatechin gallate (EGCG). Formation of trifluoperazine glucuronide, serotonin glucuronide, and mycophenolic acid phenolic glucuronide was used as an index reaction for UGT1A4, UGT1A6, and UGT1A9 activities, respectively, in human liver microsomes. Inhibition potency was expressed as the concentration of the inhibitor at 50% activity (IC(50)) and the volume in which the dose could be diluted to generate an IC(50)-equivalent concentration [volume/dose index (VDI)]. Potential inhibitors were EGCG for UGT1A4, milk thistle for both UGT1A6 and UGT1A9, saw palmetto for UGT1A6, and cranberry for UGT1A9. EGCG inhibited UGT1A4 with an IC(50) value of (mean ± S.E.) 33.8 ± 3.1 μg/ml. Milk thistle inhibited both UGT1A6 and UGT1A9 with IC(50) values of 59.5 ± 3.6 and 33.6 ± 3.1 μg/ml, respectively. Saw palmetto and cranberry weakly inhibited UGT1A6 and UGT1A9, respectively, with IC(50) values >100 μg/ml. For each inhibition, VDI was calculated to determine the potential of achieving IC(50)-equivalent concentrations in vivo. VDI values for inhibitors indicate a potential for inhibition of first-pass glucuronidation of UGT1A4, UGT1A6, and UGT1A9 substrates. These results highlight the possibility of herb-drug interactions through modulation of UGT enzyme activities. Further clinical studies are warranted to investigate the in vivo extent of the observed interactions.

Effects of herbal supplements on drug glucuronidation. Review of clinical, animal, and in vitro studies

The use of herbal supplements has increased steadily over the last decade. Recent surveys show that many people who take herbal supplements also take prescription and nonprescription drugs, increasing the risk for potential herb-drug interactions. While cytochrome P450-mediated herb-drug interactions have been extensively characterized, the effects of herbal extracts and constituents on UDP-glucuronosyl transferase (UGT) enzymes have not been adequately studied. Thus, the purpose of this review is to evaluate current evidence on the glucuronidation of phytochemicals and the potential for UGT-mediated herb-drug interactions with the top-selling herbal supplements in the United States and Europe. IN VITRO and animal studies indicate that cranberry, GINKGO BILOBA, grape seed, green tea, hawthorn, milk thistle, noni, soy, St. John's wort, and valerian are rich in phytochemicals that can modulate UGT enzymes. However, the IN VIVO consequences of these interactions are not well understood. Only three clinical studies have investigated the effects of herbal supplements on drugs cleared primarily through UGT enzymes. Evidence on the potential for commonly used herbal supplements to modulate UGT-mediated drug metabolism is summarized. Moreover, the need for further research to determine the clinical consequences of the described interactions is highlighted.

Inhibitory effects of commonly used herbal extracts on UGT1A1 enzyme activity

Commonly used herbal supplements were screened for their potential to inhibit UGT1A1 activity using human liver microsomes. Extracts screened included ginseng, echinacea, black cohosh, milk thistle, garlic, valerian, saw palmetto, and green tea epigallocatechin gallate (EGCG). Estradiol-3-O-glucuronide (E-3-G) formation was used as the index of UGT1A1 activity. All herbal extracts except garlic showed inhibition of UGT1A1 activity at one or more of the three concentrations tested. A volume per dose index (VDI) was calculated to estimate the volume in which the daily dose should be diluted to obtain an IC(50)-equivalent concentration. EGCG, echinacea, saw palmetto, and milk thistle had VDI values >2.0 L per dose unit, suggesting a higher potential for interaction. Inhibition curves were constructed for EGCG, echinacea, saw palmetto, and milk thistle. IC(50) values were (mean ± SE) 7.8 ± 0.9, 211.7 ± 43.5, 55.2 ± 9.2, and 30.4 ± 6.9 µg/ml for EGCG, echinacea, saw palmetto, and milk thistle extracts, respectively. Based on our findings, inhibition of UGT1A1 by milk thistle and EGCG and to a lesser extent by echinacea and saw palmetto is plausible, particularly in the intestine where higher extract concentrations are anticipated. Further clinical studies are warranted.

Inhibition of intestinal and hepatic glucuronidation of mycophenolic acid by Ginkgo biloba extract and flavonoids

Herb-drug interactions have received more attention in recent years because of the widespread popularity of herbal supplements. However, there are limited data on the effect of herbs on glucuronidation in humans. The goal of this work was to examine the effect of Ginkgo biloba extract and its main flavonoid and terpene lactone constituents on mycophenolic acid (MPA) 7-O-glucuronidation. Human liver (HLM) and intestinal (HIM) microsomes were incubated with MPA and G. biloba extract (unhydrolyzed or acid-hydrolyzed), quercetin, kaempferol, ginkgolide A, ginkgolide B, or bilobalide. MPA-7-O-glucuronide formation was inhibited in HLM and HIM incubations by unhydrolyzed [IC(50) = 84.3 (HLM) and 6.9 (HIM) microg/ml] and hydrolyzed [IC(50) = 20.9 (HLM) and 4.3 (HIM) microg/ml] G. biloba extracts, quercetin [IC(50) = 19.1 (HLM) and 5.8 (HIM) microM], and kaempferol [IC(50) = 23.1 (HLM) and 7.7 (HIM) microM]. Terpene lactones did not show inhibition of MPA glucuronidation. Quercetin was a mixed-type inhibitor in HLM and HIM incubations [K(i) = 11.3 (HLM) and 2.8 (HLM) microM], whereas kaempferol was a noncompetitive inhibitor in HLM (K(i) = 33.7 microM) and a mixed-type inhibitor in HIM (K(i) = 4.5 microM). These results indicate that G. biloba extract or quercetin- and kaempferol-rich supplements may inhibit intestinal and hepatic glucuronidation of MPA. Future studies are needed to evaluate the clinical significance of this interaction.