Mechanistic Determinants of Daprodustat Drug-Drug Interactions and Pharmacokinetics in Hepatic Dysfunction and Chronic Kidney Disease: Significance of OATP1B-CYP2C8 Interplay.

Daprodustat is the first oral hypoxia-inducible factor prolyl hydroxylase inhibitor approved recently for the treatment of anemia caused by chronic kidney disease (CKD) in adults receiving dialysis. We evaluated the role of organic anion transporting polypeptide (OATP)1B-mediated hepatic uptake transport in the pharmacokinetics (PKs) of daprodustat using in vitro and in vivo studies, and physiologically-based PK (PBPK) modeling of its drug-drug interactions (DDIs) with inhibitor drugs. In vitro, daprodustat showed specific transport by OATP1B1/1B3 in the transfected cell systems and primary human and monkey hepatocytes. A single-dose oral rifampin (OATP1B inhibitor) reduced daprodustat intravenous clearance by a notable 9.9 ± 1.2-fold (P < 0.05) in cynomolgus monkeys. Correspondingly, volume of distribution at steady-state was also reduced by 5.0 ± 1.1-fold, whereas the half-life change was minimal (1.5-fold), corroborating daprodustat hepatic uptake inhibition by rifampin. A PBPK model accounting for OATP1B-CYP2C8 interplay was developed, which well described daprodustat PK and DDIs with gemfibrozil (CYP2C8 and OATP1B inhibitor) and trimethoprim (weak CYP2C8 inhibitor) within 25% error of the observed data in healthy subjects. About 18-fold increase in daprodustat area under the curve (AUC) following gemfibrozil treatment was found to be associated with strong CYP2C8 inhibition and moderate OATP1B inhibition. Moreover, PK modulation in hepatic dysfunction and subjects with CKD, in comparison to healthy control, was well-captured by the model. CYP2C8 and/or OATP1B inhibitor drugs (e.g., gemfibrozil, clopidogrel, rifampin, and cyclosporine) were predicted to perpetrate moderate-to-strong DDIs in healthy subjects, as well as, in target CKD population. Daprodustat can be used as a sensitive CYP2C8 index substrate in the absence of OATP1B modulation.

Effect of Strong CYP3A4 Inhibition, CYP3A4 Induction, and OATP1B1/3 Inhibition on the Pharmacokinetics of a Single Oral Dose of Sotorasib.

Sotorasib is a small molecule that irreversibly inhibits the Kirsten rat sarcoma viral oncogene homolog (KRAS) protein with a G12C amino acid substitution mutant protein. The impact of cytochrome P450 (CYP) 3A4 inhibition and induction on sotorasib pharmacokinetics (PKs) was evaluated in 2 separate studies in healthy volunteers (N = 14/study). The impact of CYP3A4 inhibition was interrogated utilizing repeat doses of 200 mg of itraconazole, a strong CYP3A4 inhibitor, on 360 mg of sotorasib PKs. The impact of CYP3A4 induction was interrogated utilizing multiple doses of 600 mg of rifampin, a strong CYP3A4 inducer. Additionally, the impact of organic anion transporting polypeptide (OATP) 1B1/3 inhibition on 960 mg of sotorasib PKs was interrogated after a single dose of 600 mg of rifampin. CYP3A4 inhibition did not significantly impact sotorasib Cmax but did lead to a 26% increase in sotorasib AUCinf. CYP3A4 induction decreased sotorasib Cmax by 35% and AUCinf by 51%. OATP1B1/3 inhibition decreased sotorasib Cmax and AUCinf by 16% and 23%, respectively. These results support that sotorasib can be given together with strong CYP3A4 and OATP1B1/3 inhibitors but the co-administration of sotorasib and strong CYP3A4 inducers should be avoided.

Clinical Evaluation of the Effect of Encorafenib on Bupropion, Rosuvastatin, and Coproporphyrin I and Considerations for Statin Coadministration.

BACKGROUND AND OBJECTIVES: Encorafenib is a kinase inhibitor indicated for the treatment of patients with unresectable or metastatic melanoma or metastatic colorectal cancer, respectively, with selected BRAF V600 mutations. A clinical drug-drug interaction (DDI) study was designed to evaluate the effect of encorafenib on rosuvastatin, a sensitive substrate of OATP1B1/3 and breast cancer resistance protein (BCRP), and bupropion, a sensitive CYP2B6 substrate. Coproporphyrin I (CP-I), an endogenous substrate for OATP1B1, was measured in a separate study to deconvolute the mechanism of transporter DDI. METHODS: DDI study participants received a single oral dose of rosuvastatin (10 mg) and bupropion (75 mg) on days - 7, 1, and 14 and continuous doses of encorafenib (450 mg QD) and binimetinib (45 mg BID) starting on day 1. The CP-I data were collected from participants in a phase 3 study who received encorafenib (300 mg QD) and cetuximab (400 mg/m2 initial dose, then 250 mg/m2 QW). Pharmacokinetic and pharmacodynamic analysis was performed using noncompartmental and compartmental methods. RESULTS: Bupropion exposure was not increased, whereas rosuvastatin Cmax and area under the receiver operating characteristic curve (AUC) increased approximately 2.7 and 1.6-fold, respectively, following repeated doses of encorafenib and binimetinib. Increase in CP-I was minimal, suggesting that the primary effect of encorafenib on rosuvastatin is through BCRP. Categorization of statins on the basis of their metabolic and transporter profile suggests pravastatin would have the least potential for interaction when coadministered with encorafenib. CONCLUSION: The results from these clinical studies suggest that encorafenib does not cause clinically relevant CYP2B6 induction or inhibition but is an inhibitor of BCRP and may also inhibit OATP1B1/3 to a lesser extent. Based on these results, it may be necessary to consider switching statins or reducing statin dosage accordingly for coadministration with encorafenib. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT03864042, registered 6 March 2019.

Effect of major components of Tripterygium wilfordii Hook. f on the uptake function of organic anion transporting polypeptide 1B1.

Organic anion transporting polypeptide 1B1 (OATP1B1), which is specifically expressed at the basolateral membrane of human hepatocytes, is well recognized as the key determinant in the pharmacokinetics of a wide variety of drugs and considered as an important drug-drug interaction (DDI) site. Triptergium wilfordii Hook. f. (TWHF) is a traditional Chinese medicine that has a long history in treating diseases and more pharmacological effects were demonstrated recently. Components of TWHF mainly belong to the groups of alkaloids, diterpenoids, and triterpenoids. However, whether TWHF constituents are involved in herb-drug interaction (HDI) remains largely unknown. In the present study, we investigated the effect of four major components of TWHF, i.e. Triptolide (TPL), Celastrol (CL), and two alkaloids Wilforine (WFR) and Wilforgine (WFG) on the function of OATP1B1. It was found that co-incubation of these compounds greatly inhibited the uptake function of OATP1B1, with WFG (IC50 = 3.63 ± 0.61 µM) and WFR (IC50 = 3.91 ± 0.30 µM) showing higher inhibitory potency than TPL (IC50 = 184 ± 36 µM) and CL (IC50 = 448 ± 81 µM). Kinetic analysis revealed that co-incubation of WFG or WFR led to the reduction of both Km and Vmax of the DCF uptake. On the other hand, pre-incubation of WFG or WFR increased Km value of OATP1B1; while CL affected both Km and Vmax. In conclusion, co- and pre-incubation of the tested TWHF components inhibited OATP1B1 activity in different manners. Although co-incubation of WFG and WFR did not seem to directly compete with the substrates, pre-incubation of these alkaloids may alter the substrate-transporter interaction.

Biomarker-Informed Model-Based Risk Assessment of Organic Anion Transporting Polypeptide 1B Mediated Drug-Drug Interactions.

Quantitative prediction of drug-drug interactions (DDIs) involving organic anion transporting polypeptide (OATP)1B1/1B3 inhibition is limited by uncertainty in the translatability of experimentally determined in vitro inhibition potency (half-maximal inhibitory concentration (IC50 )). This study used an OATP1B endogenous biomarker-informed physiologically-based pharmacokinetic (PBPK) modeling approach to predict the effect of inhibitor drugs on the pharmacokinetics (PKs) of OATP1B substrates. Initial static analysis with about 42 inhibitor drugs, using in vitro IC50 values and unbound liver inlet concentrations (Iin,max,u ), suggested in vivo OATP1B inhibition risk for drugs with R-value (1+ Iin,max,u /IC50 ) above 1.5. A full-PBPK model accounting for transporter-mediated hepatic disposition was developed for coproporphyrin I (CP-I), an endogenous OATP1B biomarker. For several inhibitors (cyclosporine, diltiazem, fenebrutinib, GDC-0810, itraconazole, probenecid, and rifampicin at 3 different doses), PBPK models were developed and verified against available CP-I plasma exposure data to obtain in vivo OATP1B inhibition potency-which tend to be lower than the experimentally measured in vitro IC50 by about 2-fold (probenecid and rifampicin) to 37-fold (GDC-0810). Models verified with CP-I data are subsequently used to predict DDIs with OATP1B probe drugs, rosuvastatin and pitavastatin. The predicted and observed area under the plasma concentration-time curve ratios are within 20% error in 55% cases, and within 30% error in 89% cases. Collectively, this comprehensive study illustrates the adequacy and utility of endogenous biomarker-informed PBPK modeling in mechanistic understanding and quantitative predictions of OATP1B-mediated DDIs in drug development.

Interactions of anti-COVID-19 drug candidates with hepatic transporters may cause liver toxicity and affect pharmacokinetics.

Transporters in the human liver play a major role in the clearance of endo- and xenobiotics. Apical (canalicular) transporters extrude compounds to the bile, while basolateral hepatocyte transporters promote the uptake of, or expel, various compounds from/into the venous blood stream. In the present work we have examined the in vitro interactions of some key repurposed drugs advocated to treat COVID-19 (lopinavir, ritonavir, ivermectin, remdesivir and favipiravir), with the key drug transporters of hepatocytes. These transporters included ABCB11/BSEP, ABCC2/MRP2, and SLC47A1/MATE1 in the canalicular membrane, as well as ABCC3/MRP3, ABCC4/MRP4, SLC22A1/OCT1, SLCO1B1/OATP1B1, SLCO1B3/OATP1B3, and SLC10A1/NTCP, residing in the basolateral membrane. Lopinavir and ritonavir in low micromolar concentrations inhibited BSEP and MATE1 exporters, as well as OATP1B1/1B3 uptake transporters. Ritonavir had a similar inhibitory pattern, also inhibiting OCT1. Remdesivir strongly inhibited MRP4, OATP1B1/1B3, MATE1 and OCT1. Favipiravir had no significant effect on any of these transporters. Since both general drug metabolism and drug-induced liver toxicity are strongly dependent on the functioning of these transporters, the various interactions reported here may have important clinical relevance in the drug treatment of this viral disease and the existing co-morbidities.

Regulatory guidelines do not accurately predict tolvaptan and metabolite interactions at BCRP, OATP1B1, and OAT3 transporters.

Tolvaptan (TLV) was US Food and Drug Administration (FDA)-approved for the indication to slow kidney function decline in adults at risk of rapidly progressing autosomal dominant polycystic kidney disease in 2018. In vitro, TLV was a breast cancer resistance protein (BCRP) inhibitor, whereas the oxobutyric acid metabolite of TLV (DM-4013) was an inhibitor of organic anion transport polypeptide (OATP)1B1 and organic anion transporter (OAT)3. Based on the 2017 FDA guidance, potential for clinically relevant inhibition at these transporters was indicated for the highest TLV regimen. Consequently, two postmarketing clinical trials in healthy subjects were required. In trial 1, 5 mg rosuvastatin calcium (BCRP and OATP1B1 substrate) was administered alone, with 90 mg TLV or 48 h following 7 days of once daily 300 mg TLV (i.e., in the presence of DM-4103). In trial 2, 40 mg furosemide (OAT3 substrate) was administered alone and in presence of DM-4103. For BCRP, rosuvastatin geometric mean ratios (90% confidence intervals [CIs]) for maximum plasma concentration (Cmax ) were 1.54 (90% CI 1.26-1.88) and for area under the concentration-time curve from time 0 to the time of the last measurable concentration (AUCt ) were 1.69 (90% CI 1.34-2.14), indicating no clinically significant interaction. DM-4103 produced no clinically meaningful changes in rosuvastatin or furosemide concentrations, indicating no inhibition at OATP1B1 or OAT3. The BCRP prediction assumed the drug dose is completely soluble in 250 ml; TLV has solubility of ~0.01 g/250 ml. For OATP1B1/OAT3, if fraction unbound for plasma protein binding (PPB) is less than 1%, then 1% is assumed. DM-4103 has PPB greater than 99.8%. Use of actual drug substance solubility and unbound fraction in plasma would have produced predictions consistent with the clinical results.

Further Evaluation of Coproporphyrins as Clinical Endogenous Markers for OATP1B.

Coproporphyrins (CP-I and CP-III) in plasma are considered potential markers for assessing liver organic anion-transporting polypeptide transporter OATP1B activity and monitoring OATP1B-mediated drug-drug interactions (DDIs) in clinical settings. However, the effect of altered renal clearance (CLrenal ) on CP-I and CP-III plasma exposure has rarely been examined. Therefore, the purpose of this study is to further evaluate CP-I and CP-III as clinical endogenous markers for OATP1B activity and to investigate the impact of CLrenal on DDI assessments for the first time. In this study, 18 healthy participants were recruited to receive RO7049389 (a potential inhibitor of OATP1B) 800 mg twice daily for 6 days and a single dose of pitavastatin (a probe drug of OATP1B) before and after RO7049389 treatment. Plasma concentrations of pitavastatin, CP I, CP III, and the amounts of CP-I and CP-III excreted in urine were measured. Seventeen healthy participants completed the study. After multiple doses of RO7049389, the area under the plasma concentration-time curve from time 0 to 12 hours of pitavastatin increased 1.95-fold (90% confidence interval [CI], 1.58-2.41), while for CP-I and CP-III it increased 3.00-fold (90%CI, 2.35-3.82) and 2.84-fold (90%CI, 2.22-3.65), respectively. Concurrently, the CLrenal of CP-I decreased by 31% (90%CI, 23%-39%), and that of CP-III decreased by 70% (90%CI, 61%-77%). In conclusion, CP-I and CP-III in plasma display the potential to be applied as endogenous markers for the evaluation of OATP1B inhibition in clinical trials. While renal transporters contribute significantly to the CLrenal of CP-III, it would be better to investigate the impact of the CLrenal on plasma exposure of CP-III during clinical DDI assessments.

Rhabdomyolysis and acute kidney injury induced by the association of rosuvastatin and abiraterone: A case report and review of the literature.

INTRODUCTION: Abiraterone acetate is an inhibitor of androgens biosynthesis, approved as first-line treatment in castration-resistant prostate cancer and metastatic castration-sensitive prostate cancer. Abiraterone has been rarely associated with severe rhabdomyolysis, but the mechanism of muscle toxicity is unknown. CASE REPORT: We hereby present a case of severe rhabdomyolysis resulting in acute on chronic kidney injury following abiraterone initiation in a patient previously under rosuvastatin. MANAGEMENT AND OUTCOME: Rhabdomyolysis was resolutive after rosuvastatin and abiraterone discontinuation, and kidney function recovered. There was no recurrence of muscle toxicity after re-initiation of abiraterone alone. DISCUSSION: Abiraterone selectively inhibits CYP17 as well as the hepatic transporter OATP1B1. OATP1B1 is an efflux transporter, whose function is to extract several drugs from the portal blood, allowing them to undergo hepatic metabolism. We hypothesize that abiraterone-induced inhibition of plasmatic uptake of rosuvastatin by OATP1B1 increased plasmatic concentration of rosuvastatin, leading to toxicity on muscle cells. We therefore suggest that the association between rosuvastatin and abiraterone should be avoided.

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 (Cmax ) ratio and 0-16-hour area under the concentration-time curve (AUC0-16 ) ratio relative to baseline increased with increasing GLE exposures, whereas there was a modest correlation between GLE exposure and CP-III Cmax ratio but no correlation with CP-III AUC0-16 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 Cmax (R2  = 0.65; P < 0.001) across individual subjects. Correlation analysis between GLE OATP1B1 R values and CP-I exposures (Cmax ratio and AUC0-16 ratio) suggests that an R value of > 3 can predict a biologically meaningful inhibition of OATP1B1 when the inhibitor clinical pharmacokinetic parameters are available.

6-Hydroxyindole is an endogenous long-lasting OATP1B1 inhibitor elevated in renal failure patients.

The hepatic uptake transporter organic anion transporting polypeptide (OATP) 1B1 is inhibited by some uremic toxins; however, direct inhibition can only partially explain the delayed systemic elimination of substrate drugs in renal failure patients. This study aimed to examine the long-lasting inhibition of OATP1B1 by uremic toxins and their metabolites. Preincubation of HEK293/OATP1B1 cells with 21 uremic toxins resulted in almost no change in the uptake of a typical substrate [3H]estrone-3-sulfate (E1S), although some directly inhibited [3H]E1S uptake. In contrast, preincubation with an indole metabolite, 6-hydroxyindole, reduced [3H]E1S uptake, even after the inhibitor was washed out before [3H]E1S incubation. Such long-lasting inhibition by 6-hydroxyindole was time-dependent and recovered after a 3-h incubation without 6-hydroxyindole. Preincubation with 6-hydroxyindole increased the Km for [3H]E1S uptake with minimal change in Vmax. This was compatible with no change in the cell-surface expression of OATP1B1, as assessed by a biotinylation assay. Preincubation with 6-hydroxyindole reduced [3H]E1S uptake in human hepatocytes without changes in OATP1B1 mRNA. Plasma concentration of 6-hydroxyindole in renal failure patients increased as renal function decreased, but might be insufficient to exhibit potent OATP1B1 inhibition. In conclusion, 6-hydroxyindole is an endogenous long-lasting OATP1B1 inhibitor with elevated plasma concentrations in renal failure patients.

Calibrating the In Vitro-In Vivo Correlation for OATP-Mediated Drug-Drug Interactions with Rosuvastatin Using Static and PBPK Models.

Organic anion-transporting polypeptide (OATP) 1B1/3-mediated drug-drug interaction (DDI) potential is evaluated in vivo with rosuvastatin (RST) as a probe substrate in clinical studies. We calibrated our assay with RST and estradiol 17-ß-D-glucuronide (E217ßG)/cholecystokinin-8 (CCK8) as in vitro probes for qualitative and quantitative prediction of OATP1B-mediated DDI potential for RST. In vitro OATP1B1/1B3 inhibition using E217ßG and CCK8 yielded higher area under the curve (AUC) ratio (AUCR) values numerically with the static model, but all probes performed similarly from a qualitative cutoff-based prediction, as described in regulatory guidances. However, the magnitudes of DDI were not captured satisfactorily. Considering that clearance of RST is also mediated by gut breast cancer resistance protein (BCRP), inhibition of BCRP was also incorporated in the DDI prediction if the gut inhibitor concentrations were 10 × IC50 for BCRP inhibition. This combined static model closely predicted the magnitude of RST DDI with root-mean-square error values of 0.767-0.812 and 1.24-1.31 with and without BCRP inhibition, respectively, for in vitro-in vivo correlation of DDI. Physiologically based pharmacokinetic (PBPK) modeling was also used to simulate DDI between RST and rifampicin, asunaprevir, and velpatasvir. Predicted AUCR for rifampicin and asunaprevir was within 1.5-fold of that observed, whereas that for velpatasvir showed a 2-fold underprediction. Overall, the combined static model incorporating both OATP1B and BCRP inhibition provides a quick and simple mathematical approach to quantitatively predict the magnitude of transporter-mediated DDI for RST for routine application. PBPK complements the static model and provides a framework for studying molecules when a dynamic model is needed. SIGNIFICANCE STATEMENT: Using 22 drugs, we show that a static model for organic anion-transporting polypeptide (OATP) 1B1/1B3 inhibition can qualitatively predict potential for drug-drug interaction (DDI) using a cutoff-based approach, as in regulatory guidances. However, consideration of both OATP1B1/3 and gut breast cancer resistance protein inhibition provided a better prediction of the magnitude of the transporter-mediated DDI of these inhibitors with rosuvastatin. Based on these results, we have proposed an empirical mechanistic-static approach for a more reliable prediction of transporter-mediated DDI liability with rosuvastatin that drug development teams can leverage.

Assessment of Clinical Drug-Drug Interactions of Elagolix, a Gonadotropin-Releasing Hormone Receptor Antagonist.

Elagolix is an oral gonadotropin-releasing hormone receptor antagonist indicated for the management of endometriosis-associated pain and in combination with estradiol/norethindrone acetate indicated for the management of heavy menstrual bleeding associated with uterine leiomyomas (fibroids) in premenopausal women. Elagolix coadministered with estradiol/norethindrone acetate is in late-stage development for the management of heavy menstrual bleeding associated with uterine fibroids. Based on the in vitro profile of elagolix metabolism and disposition, 9 drug-drug interaction (DDI) studies evaluating the victim and perpetrator characteristics of elagolix were conducted in 144 healthy volunteers. As a victim of cytochrome P450 (CYPs) and transporter-mediated DDIs, elagolix area under the curve (AUC) increased by ∼2-fold following coadministration with ketoconazole and by ∼5- and ∼2-fold with single and multiple doses of rifampin, respectively. As a perpetrator, elagolix decreased midazolam AUC (90% confidence interval) by 54% (50%-59%) and increased digoxin AUC by 32% (23%-41%). Elagolix decreased rosuvastatin AUC by 40% (29%-50%). No clinically significant changes in exposure on coadministration with sertraline or fluconazole occurred. A elagolix 150-mg once-daily regimen should be limited to 6 months with strong CYP3A inhibitors and rifampin because of the potential increase in bone mineral density loss, as described in the drug label. A 200-mg twice-daily regimen is recommended for no more than 1 month with strong CYP3A inhibitors and not recommended with rifampin. Elagolix is contraindicated with strong organic anion transporter polypeptide B1 inhibitors (eg, cyclosporine and gemfibrozil). Consider increasing the doses of midazolam and rosuvastatin when coadministered with elagolix, and individualize therapy based on patient response. Clinical monitoring is recommended for P-glycoprotein substrates with a narrow therapeutic window (eg, digoxin). Dose adjustments are not required for sertraline, fluconazole, bupropion (or any CYP2B6 substrate), or elagolix when coadministered.

Static Model-Based Assessment of OATP1B1-Mediated Drug Interactions with Preincubation-Dependent Inhibitors Based on Inactivation and Recovery Kinetics.

Quantitative assessment of drug-drug interactions (DDIs) via organic anion transporting polypeptide (OATP) 1B1 is one of the key issues in drug development. Although OATP1B1 inhibition exhibits unique characteristics, including preincubation dependence for some inhibitors, a limited approach has been attempted based on the static model that considers such preincubation dependence in the prediction of DDIs via OATP1B1. The present study aimed to establish the prediction of DDIs via OATP1B1 using preincubation-dependent inhibitors based on the static model and incorporating both inactivation and recovery of OATP1B1 activity. Cyclosporine A was selected as a preincubation-dependent inhibitor, as well as five substrates that include probes and pharmaceuticals. The inhibition ratio (R value) calculated on the basis of a conventional static model, considering inhibition of OATP1B1 and contribution ratio of OATP1B1 to the overall hepatic uptake, was much lower than the reported AUC ratio, even when IC50 values were estimated after preincubation conditions. Conversely, the R value that was estimated by considering inactivation and recovery parameters was closer to the AUC ratio. The R value that was calculated assuming the complete contribution of OATP1B1 was much higher than the AUC ratio, avoiding false-negative prediction. The R value estimated by considering inactivation and recovery for another combination of a preincubation-dependent inhibitor, asunaprevir, and substrate drug, rosuvastatin, was also closer to the AUC ratio. Thus, R values calculated based on such OATP1B1 kinetics would be potential alternative indexes for the quantitative prediction of OATP1B1-mediated DDIs using preincubation-dependent inhibitors, although this prediction is affected by estimation of the contribution ratio of substrates. SIGNIFICANCE STATEMENT: Static model-based quantitative prediction of organic anion transporting polypeptide 1B1-mediated drug-drug interactions induced by preincubation-dependent inhibitors was newly proposed to avoid false-negative prediction.

Detection of Weak Organic Anion-Transporting Polypeptide 1B Inhibition by Probenecid with Plasma-Based Coproporphyrin in Humans.

Probenecid (PROB) is a clinical probe inhibitor of renal organic anion transporter (OAT) 1 and OAT3 that inhibits in vitro activity of hepatic drug transporters OATP1B1 and OATP1B3. It was hypothesized that PROB could potentially affect the disposition of OATP1B drug substrates. The plasma levels of the OATP1B endogenous biomarker candidates, including coproporphyrin I (CPI), CPIII, hexadecanedioate (HDA), and tetradecanedioate (TDA), were examined in 14 healthy subjects treated with PROB. After oral administration with 1000 mg PROB alone and in combination with furosemide (FSM), AUC (0-24 h) values were 1.39 ± 0.21-fold and 1.57 ± 0.41-fold higher than predose levels for CPI and 1.34 ± 0.16-fold and 1.45 ± 0.57-fold higher for CPIII. Despite increased systemic exposures, no decreases in CPI and CPIII renal clearance were observed (0.97 ± 0.38-fold and 1.16 ± 0.51-fold for CPI, and 1.34 ± 0.53-fold and 1.50 ± 0.69-fold for CPIII, respectively). These results suggest that the increase of CP systemic exposure is caused by OATP1B inhibition. Consistent with this hypothesis, PROB inhibited OATP1B1- and OATP1B3-mediated transport of CPI in a concentration-dependent manner, with IC50 values of 167 ± 42.0 and 76.0 ± 17.2 µM, respectively, in transporter-overexpressing human embryonic kidney cell assay. The inhibition potential was further confirmed by CPI and CPIII hepatocyte uptake experiments. In contrast, administration of PROB alone did not change AUC (0-24 h) of HDA and TDA relative to prestudy levels, although the administration of PROB in combination with FSM increased HDA and TDA levels compared with FSM alone (1.02 ± 0.18-fold and 0.90 ± 0.20-fold vs. 1.71 ± 0.43-fold and 1.62 ± 0.40-fold). Taken together, these findings indicate that PROB displays weak OATP1B inhibitory effects in vivo and that coproporphyrin is a sensitive endogenous probe of OATP1B inhibition. This study provides an explanation for the heretofore unknown mechanism responsible for PROB's interaction with other xenobiotics. SIGNIFICANCE STATEMENT: This study suggested that PROB is a weak clinical inhibitor of OATP1B based on the totality of evidence from the clinical interaction between PROB and CP and the in vitro inhibitory effect of PROB on OATP1B-mediated CP uptake. It demonstrates a new methodology of utilizing endogenous biomarkers to evaluate complex drug-drug interaction, providing explanation for the heretofore unknown mechanism responsible for PROB's inhibition. It provides evidence to strengthen the claim that CP is a sensitive circulating endogenous biomarker of OATP1B inhibition.

Absorption and Disposition of Coproporphyrin I (CPI) in Cynomolgus Monkeys and Mice: Pharmacokinetic Evidence to Support the Use of CPI to Inform the Potential for Organic Anion-Transporting Polypeptide Inhibition.

Despite a recent expansion in the recognition of the potential utility of coproporphyrin (CP) as an endogenous biomarker of organic anion-transporting polypeptide (OATP) 1B activity, there have been few detailed studies of CP's pharmacokinetic behavior and an overall poor understanding of its pharmacokinetic fate from tissues and excretion. Here, we describe the pharmacokinetics of octadeuterium-labeled coproporphyrin I (CPI-d8) in cynomolgus monkeys following oral and intravenous administration. CPI-d8 has a half-life and bioavailability of 7.6 hours and 3.2%, respectively. Cynomolgus monkeys received oral cyclosporin A (CsA) at 4, 20, and 100 mg/kg which yielded maximum blood concentrations (C max) and area under the plasma concentration-time curve (AUC) values of 0.19, 2.5, and 3.8 µM, and 2.7, 10.5, and 26.6 µM·h, respectively. The apparent CsA-dose dependent increase in the AUC ratio of CPI-d8 (1.8, 6.2, and 10.5), CPI (1.1, 1.4, and 4.4), and CPIII (1.1, 1.8, and 4.6) at 4, 20, and 100 mg, respectively. In contrast, the plasma concentrations of CPI and CPIII were generally not affected by intravenous administration of the renal organic anion and cation transporter inhibitors (probenecid and pyrimethamine, respectively). In addition, tritium-labeled coproporphyrin I ([3H]CPI) showed specific and rapid distribution to the liver, intestine, and kidney after an intravenous dose in mice using quantitative whole-body autoradiography. Rifampin markedly reduced the liver and intestinal uptake of [3H]CPI while increasing the kidney uptake. Taken together, these results suggest that hepatic OATP considerably affects the disposition of CPI in animal models, indicating CPI is a sensitive and selective endogenous biomarker of OATP inhibition. SIGNIFICANCE STATEMENT: This study demonstrated that coproporphyrin I (CPI) has favorable oral absorption, distribution, and elimination profiles in monkeys and mice as an endogenous biomarker. It also demonstrated its sensitivity and selectivity as a probe of organic anion-transporting polypeptide (OATP) 1B activity. The study reports, for the first time, in vivo pharmacokinetics, tissue distribution, sensitivity, and selectivity of CPI as an OATP1B endogenous biomarker in animals. The data provide preclinical support for exploration of its utility as a sensitive and selective circulating OATP biomarker in humans.

Physiologically-Based Pharmacokinetic Model-Informed Drug Development for Fenebrutinib: Understanding Complex Drug-Drug Interactions.

Fenebrutinib is a CYP3A substrate and time-dependent inhibitor, as well as a BCRP and OATP1B transporter inhibitor in vitro. Physiologically-based pharmacokinetic (PBPK) modeling strategies with the ultimate goal of understanding complex drug-drug interactions (DDIs) and proposing doses for untested scenarios were developed. The consistency in the results of two independent approaches, PBPK simulation and endogenous biomarker measurement, supported that the observed transporter DDI is primarily due to fenebrutinib inhibition of intestinal BCRP, rather than hepatic OATP1B. A mechanistic-absorption model accounting for the effects of excipient complexation with fenebrutinib was used to rationalize the unexpected observation of itraconazole-fenebrutinib DDI (maximum plasma concentration (Cmax ) decreased, and area under the curve (AUC) increased). The totality of the evidence from sensitivity analysis and clinical and nonclinical data suggested that fenebrutinib is likely a sensitive CYP3A substrate. This advanced PBPK application allowed the use of model-informed approach to facilitate the development of concomitant medication recommendations for fenebrutinib without requiring additional clinical DDI studies.

Drug interaction study of flavonoids toward OATP1B1 and their 3D structure activity relationship analysis for predicting hepatoprotective effects.

Organic anion transporting polypeptide 1B1 (OATP1B1), a liver-specific uptake transporter, was associated with drug induced liver injury (DILI). Screening and identifying potent OATP1B1 inhibitors with little toxicity is of great value in reducing OATP1B1-mediated DILI. Flavonoids are a group of polyphenols ubiquitously present in vegetables, fruits and herbal products, some of them were reported to produce transporter-mediated DDI. Our objective was to investigate potential inhibitors of OATP1B1 from 99 flavonoids, and to assess the hepatoprotective effects on bosentan induced liver injury. Eight flavonoids, including biochanin A, hispidulin, isoliquiritigenin, isosinensetin, kaempferol, licochalcone A, luteolin and sinensetin exhibited significant inhibition (>50 %) on OATP1B1 in OATP1B1-HEK293 cells, which reduced the OATP1B1-mediated influx of methotrexate, accordingly decreased its cytotoxicity in OATP1B1-HEK293 cells and increased its AUC0-t in different extents in rats, from 28.27%-82.71 %. In bosentan-induced rat liver injury models, 8 flavonoids reduced the levels of serum total bile acid (TBA) and the liver concentration of bosentan in different degrees. Among them, kaempferol decreased the concentration most significantly, by 54.17 %, which indicated that flavonoids may alleviate bosentan-induced liver injury by inhibiting OATP1B1-mediated bosentan uptake. Furthermore, the pharmacophore model indicated the hydrogen bond acceptors and hydrogen bond donors may play critical role in the potency of flavonoids inhibition on OATP1B1. Taken together, our findings would provide helpful information for predicting the potential risks of flavonoid-containing food/herb-drug interactions in humans and alleviating bosentan -induced liver injury by OATP1B1 regulation.

Alteration in the Plasma Concentrations of Endogenous Organic Anion-Transporting Polypeptide 1B Biomarkers in Patients with Non-Small Cell Lung Cancer Treated with Paclitaxel.

Paclitaxel has been considered to cause OATP1B-mediated drug-drug interactions at therapeutic doses; however, its clinical relevance has not been demonstrated. This study aimed to elucidate in vivo inhibition potency of paclitaxel against OATP1B1 and OATP1B3 using endogenous OATP1B biomarkers. Paclitaxel is an inhibitor of OATP1B1 and OATP1B3, with Ki of 0.579 ± 0.107 and 5.29 ± 3.87 µM, respectively. Preincubation potentiated its inhibitory effect on both OATP1B1 and OATP1B3, with Ki of 0.154 ± 0.031 and 0.624 ± 0.183 µM, respectively. Ten patients with non-small cell lung cancer who received 200 mg/m2 of paclitaxel by a 3-hour infusion were recruited. Plasma concentrations of 10 endogenous OATP1B biomarkers-namely, coproporphyrin I, coproporphyrin III, glycochenodeoxycholate-3-sulfate, glycochenodeoxycholate-3-glucuronide, glycodeoxycholate-3-sulfate, glycodeoxycholate-3-glucuronide, lithocholate-3-sulfate, glycolithocholate-3-sulfate, taurolithocholate-3-sulfate, and chenodeoxycholate-24-glucuronide-were determined in the patients with non-small cell lung cancer on the day before paclitaxel administration and after the end of paclitaxel infusion for 7 hours. Paclitaxel increased the area under the plasma concentration-time curve (AUC) of the endogenous biomarkers 2- to 4-fold, although a few patients did not show any increment in the AUC ratios of lithocholate-3-sulfate, glycolithocholate-3-sulfate, and taurolithocholate-3-sulfate. Therapeutic doses of paclitaxel for the treatment of non-small cell lung cancer (200 mg/m2) will cause significant OATP1B1 inhibition during and at the end of the infusion. This is the first demonstration that endogenous OATP1B biomarkers could serve as surrogate biomarkers in patients. SIGNIFICANCE STATEMENT: Endogenous biomarkers can address practical and ethical issues in elucidating transporter-mediated drug-drug interaction (DDI) risks of anticancer drugs clinically. We could elucidate a significant increment of the plasma concentrations of endogenous OATP1B biomarkers after a 3-hour infusion (200 mg/m2) of paclitaxel, a time-dependent inhibitor of OATP1B, in patients with non-small cell lung cancer. The endogenous OATP1B biomarkers are useful to assess the possibility of OATP1B-mediated DDIs in patients and help in appropriately designing a dosing schedule to avoid the DDIs.

Effect of Rifampin-Mediated OATP1B1 and OATP1B3 Transporter Inhibition on the Pharmacokinetics of the P2Y12 Receptor Antagonist Selatogrel.

In vitro studies have indicated that the P2Y12 receptor antagonist selatogrel is a substrate of organic anion-transporting-polypeptide (OATP)1B1 and OATP1B3 that are known to mediate hepatic uptake. Selatogrel is primarily eliminated via the biliary route. Therefore, the study aim was to investigate the effect of rifampin-mediated OATP1B1 and OATP1B3 inhibition on the pharmacokinetics (PK) of selatogrel. This was a randomized, double-blind, placebo-controlled, two-period, crossover study in 14 healthy subjects. In each period, a single subcutaneous dose of 4 mg selatogrel was administered, either immediately after a single intravenous 30 minutes infusion of 600 mg rifampin or after placebo. Plasma samples were collected for 36 hours and analyzed using a validated liquid chromatography-tandem mass spectrometry method. PK parameters of selatogrel were calculated using noncompartmental analysis. The effect of rifampin was explored based on geometric mean peak plasma concentration (Cmax ) and area under the concentration curve from zero to infinity (AUC0-∞ ) ratios and for time of maximum plasma concentration (Tmax ) by Wilcoxon signed rank test. In addition, the safety and tolerability of the study treatments were evaluated. The geometric mean ratios of Cmax and AUC0-∞ were 1.19 (90% confidence interval (CI) 1.11-1.28) and 1.43 (90% CI 1.36-1.51), respectively, indicating a minor selatogrel exposure increase when administered after an infusion of rifampin compared with placebo. Rifampin administration did not affect terminal half-life (t½ ) or Tmax of selatogrel. All study treatments were safe and well-tolerated. A single dose of 600 mg rifampin, a potent OATP1B1/1B3 inhibitor, did not impact the PK of selatogrel to a clinically relevant extent suggesting that OATP1B1 and OATP1B3 transporters do not play a major role in the elimination of selatogrel.