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Yuan T, Bi F, Hu K, Zhu Y, Lin Y, Yang J. Clinical Trial Data-Driven Risk Assessment of Drug-Drug Interactions: A Rapid and Accurate Decision-Making Tool. Clin Pharmacokinet 2024; 63:1147-1165. [PMID: 39102093 DOI: 10.1007/s40262-024-01404-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2024] [Indexed: 08/06/2024]
Abstract
BACKGROUND In clinical practice, the vast array of potential drug combinations necessitates swift and accurate assessments of pharmacokinetic drug-drug interactions (DDIs), along with recommendations for adjustments. Current methodologies for clinical DDI evaluations primarily rely on basic extrapolations from clinical trial data. However, these methods are limited in accuracy owing to their lack of a comprehensive consideration of various critical factors, including the inhibitory potency, dosage, and type of the inhibitor, as well as the metabolic fraction and intestinal availability of the substrate. OBJECTIVE This study aims to propose an efficient and accurate clinical pharmacokinetic-mediated DDI assessment tool, which comprehensively considers the effects of inhibitory potency and dosage of inhibitors, intestinal availability and fraction metabolized of substrates on DDI outcomes. METHODS This study focuses on DDIs caused by cytochrome P450 3A4 enzyme inhibition, utilizing extensive clinical trial data to establish a methodology to calculate the metabolic fraction and intestinal availability for substrates, as well as the concentration and inhibitory potency for inhibitors ( K i ork inact / K I ). These parameters were then used to predict the outcomes of DDIs involving 33 substrates and 20 inhibitors. We also defined the risk index for substrates and the potency index for inhibitors to establish a clinical DDI risk scale. The training set for parameter calculation consisted of 73 clinical trials. The validation set comprised 89 clinical DDI trials involving 53 drugs. which was used to evaluate the reliability of in vivo values of K i andk inact / K I , the accuracy of DDI predictions, and the false-negative rate of risk scale. RESULTS First, the reliability of the in vivo K i andk inact / K I values calculated in this study was assessed using a basic static model. Compared with values obtained from other methods, this study values showed a lower geometric mean fold error and root mean square error. Additionally, incorporating these values into the physiologically based pharmacokinetic-DDI model facilitated a good fitting of the C-t curves when the substrate's metabolic enzymes are inhibited. Second, area under the curve ratio predictions of studied drugs were within a 1.5 × margin of error in 81% of cases compared with clinical observations in the validation set. Last, the clinical DDI risk scale developed in this study predicted the actual risks in the validation set with only a 5.6% incidence of serious false negatives. CONCLUSIONS This study offers a rapid and accurate approach for assessing the risk of pharmacokinetic-mediated DDIs in clinical practice, providing a foundation for rational combination drug use and dosage adjustments.
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Affiliation(s)
- Tong Yuan
- Key Laboratory of Drug Metabolism and Pharmacokinetics, School of Pharmacy, China Pharmaceutical University, 24 Tongjiaxiang Rd, Nanjing, 210009, People's Republic of China
| | - Fulin Bi
- Key Laboratory of Drug Metabolism and Pharmacokinetics, School of Pharmacy, China Pharmaceutical University, 24 Tongjiaxiang Rd, Nanjing, 210009, People's Republic of China
| | - Kuan Hu
- Key Laboratory of Drug Metabolism and Pharmacokinetics, School of Pharmacy, China Pharmaceutical University, 24 Tongjiaxiang Rd, Nanjing, 210009, People's Republic of China
| | - Yuqi Zhu
- Jiangsu Key Laboratory of Carcinogenesis and Intervention, School of Basic Medical Sciences and Clinical Pharmacy, China Pharmaceutical University, Nanjing, People's Republic of China
| | - Yan Lin
- Department of Clinical Pharmacy, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, 639 Longmiandadao Rd, Nanjing, 211198, People's Republic of China.
| | - Jin Yang
- Key Laboratory of Drug Metabolism and Pharmacokinetics, School of Pharmacy, China Pharmaceutical University, 24 Tongjiaxiang Rd, Nanjing, 210009, People's Republic of China.
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Berglund LJ. Modulating the PI3K Signalling Pathway in Activated PI3K Delta Syndrome: a Clinical Perspective. J Clin Immunol 2023; 44:34. [PMID: 38148368 PMCID: PMC10751257 DOI: 10.1007/s10875-023-01626-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/09/2023] [Indexed: 12/28/2023]
Abstract
Activated phosphoinositide-3-kinase (PI3K) δ syndrome (APDS) is an inborn error of immunity characterised by immune dysregulation. Since the discovery of genetic mutations resulting in PI3Kδ overactivation, treatment of APDS patients has begun to focus on modulation of the PI3K pathway in addition to supportive therapies. The mTOR inhibitor sirolimus has been used effectively for some clinical manifestations of this condition, however the arrival of specific PI3Kδ inhibitor leniolisib has shown promising early results and may provide a more targeted approach. This review summarizes key aspects of PI3K pathway biology and discusses potential options for nuanced modulation of the PI3K pathway in APDS from a clinical perspective, highlighting differences from PI3K inhibition in haematological malignancies.
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Affiliation(s)
- Lucinda J Berglund
- Faculty of Medicine, University of Sydney, Sydney, NSW, Australia.
- Department of Immunopathology, Westmead Hospital, NSW Health Pathology, Westmead, Sydney, NSW, Australia.
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Quartier J, Lapteva M, Boulaguiem Y, Guerrier S, Kalia YN. Influence of Molecular Structure and Physicochemical Properties of Immunosuppressive Drugs on Micelle Formulation Characteristics and Cutaneous Delivery. Pharmaceutics 2023; 15:pharmaceutics15041278. [PMID: 37111763 PMCID: PMC10142028 DOI: 10.3390/pharmaceutics15041278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
The aim of this study was to investigate whether subtle differences in molecular properties affected polymeric micelle characteristics and their ability to deliver poorly water-soluble drugs into the skin. D-α-tocopherol-polyethylene glycol 1000 was used to prepare micelles containing ascomycin-derived immunosuppressants-sirolimus (SIR), pimecrolimus (PIM) and tacrolimus (TAC)-which have similar structures and physicochemical properties and have dermatological applications. Micelle formulations were prepared by thin-film hydration and extensively characterized. Cutaneous delivery and biodistribution were determined and compared. Sub-10 nm micelles were obtained for the three immunosuppressants with incorporation efficiencies >85%. However, differences were observed for drug loading, stability (at the highest concentration), and their in vitro release kinetics. These were attributed to differences in drug aqueous solubility and lipophilicity. Differences between the cutaneous biodistribution profiles and drug deposition in the different skin compartments pointed to the impact of differences in thermodynamic activity. Therefore, despite their structural similarities, SIR, TAC and PIM did not demonstrate the same behaviour either in the micelles or when applied to the skin. These outcomes indicate that polymeric micelles should be optimized even for closely related drug molecules and support the hypothesis that drugs are released from micelles prior to skin penetration.
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Affiliation(s)
- Julie Quartier
- School of Pharmaceutical Sciences, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
| | - Maria Lapteva
- School of Pharmaceutical Sciences, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
| | - Younes Boulaguiem
- Geneva School of Economics and Management, University of Geneva, 40 Boulevard du Pont d'Arve, 1204 Geneva, Switzerland
| | - Stéphane Guerrier
- School of Pharmaceutical Sciences, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
- Geneva School of Economics and Management, University of Geneva, 40 Boulevard du Pont d'Arve, 1204 Geneva, Switzerland
| | - Yogeshvar N Kalia
- School of Pharmaceutical Sciences, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
- Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, CMU-1 rue Michel Servet, 1211 Geneva, Switzerland
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Shen G, Moua KTY, Perkins K, Johnson D, Li A, Curtin P, Gao W, McCune JS. Precision sirolimus dosing in children: The potential for model-informed dosing and novel drug monitoring. Front Pharmacol 2023; 14:1126981. [PMID: 37021042 PMCID: PMC10069443 DOI: 10.3389/fphar.2023.1126981] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 02/14/2023] [Indexed: 04/07/2023] Open
Abstract
The mTOR inhibitor sirolimus is prescribed to treat children with varying diseases, ranging from vascular anomalies to sporadic lymphangioleiomyomatosis to transplantation (solid organ or hematopoietic cell). Precision dosing of sirolimus using therapeutic drug monitoring (TDM) of sirolimus concentrations in whole blood drawn at the trough (before the next dose) time-point is the current standard of care. For sirolimus, trough concentrations are only modestly correlated with the area under the curve, with R 2 values ranging from 0.52 to 0.84. Thus, it should not be surprising, even with the use of sirolimus TDM, that patients treated with sirolimus have variable pharmacokinetics, toxicity, and effectiveness. Model-informed precision dosing (MIPD) will be beneficial and should be implemented. The data do not suggest dried blood spots point-of-care sampling of sirolimus concentrations for precision dosing of sirolimus. Future research on precision dosing of sirolimus should focus on pharmacogenomic and pharmacometabolomic tools to predict sirolimus pharmacokinetics and wearables for point-of-care quantitation and MIPD.
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Affiliation(s)
- Guofang Shen
- Department of Hematologic Malignancies Translational Sciences, City of Hope, and Department of Hematopoietic Cell Transplantation, City of Hope Medical Center, Duarte, CA, United States
| | - Kao Tang Ying Moua
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, United States
| | - Kathryn Perkins
- Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, United States
| | - Deron Johnson
- Clinical Informatics, City of Hope Medical Center, Duarte, CA, United States
| | - Arthur Li
- Division of Biostatistics, City of Hope, Duarte, CA, United States
| | - Peter Curtin
- Department of Hematologic Malignancies Translational Sciences, City of Hope, and Department of Hematopoietic Cell Transplantation, City of Hope Medical Center, Duarte, CA, United States
| | - Wei Gao
- Division of Engineering and Applied Science, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Jeannine S. McCune
- Department of Hematologic Malignancies Translational Sciences, City of Hope, and Department of Hematopoietic Cell Transplantation, City of Hope Medical Center, Duarte, CA, United States
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Burnett GL, Yang YC, Aggen JB, Pitzen J, Gliedt MK, Semko CM, Marquez A, Evans JW, Wang G, Won WS, Tomlinson ACA, Kiss G, Tzitzilonis C, Thottumkara AP, Cregg J, Mellem KT, Choi JS, Lee JC, Zhao Y, Lee BJ, Meyerowitz JG, Knox JE, Jiang J, Wang Z, Wildes D, Wang Z, Singh M, Smith JA, Gill AL. Discovery of RMC-5552, a Selective Bi-Steric Inhibitor of mTORC1, for the Treatment of mTORC1-Activated Tumors. J Med Chem 2022; 66:149-169. [PMID: 36533617 PMCID: PMC9841523 DOI: 10.1021/acs.jmedchem.2c01658] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hyperactivation of mTOR kinase by mutations in the PI3K/mTOR pathway or by crosstalk with other mutant cancer drivers, such as RAS, is a feature of many tumors. Multiple allosteric inhibitors of mTORC1 and orthosteric dual inhibitors of mTORC1 and mTORC2 have been developed as anticancer drugs, but their clinical utility has been limited. To address these limitations, we have developed a novel class of "bi-steric inhibitors" that interact with both the orthosteric and the allosteric binding sites in order to deepen the inhibition of mTORC1 while also preserving selectivity for mTORC1 over mTORC2. In this report, we describe the discovery and preclinical profile of the development candidate RMC-5552 and the in vivo preclinical tool compound RMC-6272. We also present evidence that selective inhibition of mTORC1 in combination with covalent inhibition of KRASG12C shows increased antitumor activity in a preclinical model of KRASG12C mutant NSCLC that exhibits resistance to KRASG12C inhibitor monotherapy.
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Wilson A, Urquhart BL, Ponich T, Chande N, Gregor JC, Beaton M, Kim RB. Crohn's Disease Is Associated with Decreased CYP3A4 and P-Glycoprotein Protein Expression. Mol Pharm 2019; 16:4059-4064. [PMID: 31393129 DOI: 10.1021/acs.molpharmaceut.9b00459] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp) have broad substrate overlap and are involved in the metabolism and transport of nearly 50% of currently prescribed medications. In the intestine, CYP3A4 and P-gp are coexpressed in the enterocytes at the intestinal villous tip and act in a coordinated manner to limit drug and xenobiotic oral bioavailability prior to further metabolism and disposition in the liver. Crohn's disease (CD), a form of inflammatory bowel disease, introduces a transmural intestinal insult that disrupts the intestinal barrier function; it therefore has the potential to affect intestinal drug metabolism and transport. We hypothesized that individuals with CD have reduced intestinal expression of CYP3A4 and P-gp. We obtained intestinal biopsy samples from individuals with and without CD and quantified the expression of CYP3A4 and P-gp. When we carried out Western analysis for protein expression, we observed a significant reduction in ileal (45% decrease) and colonic (78% decrease) CYP3A4 protein expression in subjects with CD compared with those without. Similarly, an 85% reduction in colonic P-gp protein expression was seen in the CD patients. Our data highlight important and novel findings pertaining to CD-associated changes to the intestinal expression of CYP3A4 and P-gp that are of relevance to better predict substrate drug dosing for patients with CD.
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Kanaujia P, Poovizhi P, Ng WK, Tan RBH. Preparation, Characterization and Prevention of Auto-oxidation of Amorphous Sirolimus by Encapsulation in Polymeric Films Using Hot Melt Extrusion. Curr Drug Deliv 2019; 16:663-671. [PMID: 31038065 DOI: 10.2174/1567201816666190416123939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 02/11/2019] [Accepted: 02/22/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Sirolimus (SIR) is a macrocyclic lactone antibiotic and used therapeutically as a potent immunosuppressant for prophylaxis of kidney transplant rejection. The development of an oral dosage form is challenging because of very poor aqueous solubility (2.6µg/ml). The oral bioavailability of SIR is only 15-20 % and is affected by food and other drugs. The main reasons for low bioavailability are intestinal degradation by enzymes especially by cytochrome P4503A4, efflux by P-glycoprotein and hepatic first-pass metabolism. OBJECTIVE The main objective was to prepare a mouth dissolving film dosage form of amorphous SIR to improve dissolution. METHODS Crystalline SIR was transformed to its form amorphous by milling for 2 h at room temperature. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and powder x-ray diffraction (PXRD) were used for characterisation. The stability of amorphous SIR was studied at 4°C and 40°C/75% RH. Amorphous SIR was formulated as oral films by melt extrusion with polyvinylpyrrolidone- vinyl acetate (PVP-VA), Soluplus® and hydroxypropyl cellulose (HPC) as carriers. The films were characterized for drug content, physical state, dissolution profile and stability at 4°C and 40°C/75% RH. RESULTS The PRXD and DSC confirmed the conversion of crystalline SIR to amorphous form by milling. The solubility of amorphous SIR was several folds higher than its crystalline form, but amorphous SIR was highly unstable at all tested temperatures (4° and 40°C). The extruded films exhibited higher dissolution and stability compared to milled SIR powder alone, but the process of extrusion had some detrimental effect on the chemical stability of amorphous SIR. CONCLUSION The film formulations showed a significant improvement in the storage stability of the amorphous form of SIR and the solubility advantage of the amorphous form was evident in the dissolution testing. The oral films can potentially improve the bioavailability of SIR by absorption through the buccal mucosa.
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Affiliation(s)
- Parijat Kanaujia
- Institute of Chemical and Engineering Sciences, 1, Pesek Road Jurong Island, Singapore-627833, Singapore
| | - Ponnammal Poovizhi
- Institute of Chemical and Engineering Sciences, 1, Pesek Road Jurong Island, Singapore-627833, Singapore.,Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
| | - Wai Kiong Ng
- Institute of Chemical and Engineering Sciences, 1, Pesek Road Jurong Island, Singapore-627833, Singapore.,Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Reginald B H Tan
- Institute of Chemical and Engineering Sciences, 1, Pesek Road Jurong Island, Singapore-627833, Singapore.,Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore
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Xie Y, Dilibero D, Chang DH. Review of Major Drug-Drug Interactions in Thoracic Transplantation. CURRENT TRANSPLANTATION REPORTS 2018. [DOI: 10.1007/s40472-018-0200-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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9
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Emoto C, Fukuda T, Johnson TN, Adams DM, Vinks AA. Development of a Pediatric Physiologically Based Pharmacokinetic Model for Sirolimus: Applying Principles of Growth and Maturation in Neonates and Infants. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2015. [PMID: 26225230 PMCID: PMC4360665 DOI: 10.1002/psp4.17] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This study describes the maturation of sirolimus clearance in a cohort of very young pediatric patients with vascular anomalies. The relationship between allometrically scaled in vivo clearance and age was described by the Emax model in patients aged 1 month to 2 years. Consistent with the observed increase, in vitro intrinsic clearance of sirolimus using pediatric liver microsomes showed a similar age-dependent increase. In children older than 2 years, allometrically scaled sirolimus clearance did not show further maturation. Simulated clearance estimates with a sirolimus physiologically based pharmacokinetic model that included CYP3A4/5/7 and CYP2C8 maturation profiles were in close agreement with observed in vivo clearance values. In addition, physiologically based pharmacokinetic model-simulated sirolimus pharmacokinetic profiles predicted the actual observations well. These results demonstrate the utility of a physiologically based pharmacokinetic modeling approach for the prediction of the developmental trajectory of sirolimus metabolic activity and its effects on total body clearance in neonates and infants.
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Affiliation(s)
- C Emoto
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio, USA ; Department of Pediatrics, University of Cincinnati College of Medicine Cincinnati, Ohio, USA
| | - T Fukuda
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio, USA ; Department of Pediatrics, University of Cincinnati College of Medicine Cincinnati, Ohio, USA
| | - T N Johnson
- Simcyp Limited, Blades Enterprise Centre John Street, Sheffield, UK
| | - D M Adams
- Department of Pediatrics, University of Cincinnati College of Medicine Cincinnati, Ohio, USA ; Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio, USA
| | - A A Vinks
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center Cincinnati, Ohio, USA ; Department of Pediatrics, University of Cincinnati College of Medicine Cincinnati, Ohio, USA
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Emoto C, Fukuda T, Cox S, Christians U, Vinks AA. Development of a Physiologically-Based Pharmacokinetic Model for Sirolimus: Predicting Bioavailability Based on Intestinal CYP3A Content. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2013; 2:e59. [PMID: 23884207 PMCID: PMC3731827 DOI: 10.1038/psp.2013.33] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 05/05/2013] [Indexed: 01/17/2023]
Abstract
Sirolimus is an inhibitor of mammalian target of rapamycin (mTOR) and is increasingly being used in transplantation and cancer therapies. Sirolimus has low oral bioavailability and exhibits large pharmacokinetic variability. The underlying mechanisms for this variability have not been explored to a large extent. Sirolimus metabolism was characterized by in vitro intrinsic clearance estimation. Pathway contribution ranked from CYP3A4 > CYP3A5 > CYP2C8. With the well stirred and Qgut models sirolimus bioavailability was predicted at 15%. Interindividual differences in bioavailability could be attributed to variable intestinal CYP3A expression. The physiologically-based pharmacokinetics (PBPK) model developed in Simcyp predicted a high distribution of sirolimus into adipose tissue and another elimination pathway in addition to CYP-mediated metabolism. PBPK model predictive performance was acceptable with Cmax and area under the curve (AUC) estimates within 20% of observed data in a dose escalation study. The model also showed potential to assess the impact of hepatic impairment and drug–drug interaction (DDI) on sirolimus pharmacokinetics.
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Affiliation(s)
- C Emoto
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
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Raval A, Parmar A, Raval A, Bahadur P. Preparation and optimization of media using Pluronic® micelles for solubilization of sirolimus and release from the drug eluting stents. Colloids Surf B Biointerfaces 2012; 93:180-7. [DOI: 10.1016/j.colsurfb.2011.12.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 12/30/2011] [Accepted: 12/30/2011] [Indexed: 10/14/2022]
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Kim MS, Kim JS, Park HJ, Cho WK, Cha KH, Hwang SJ. Enhanced bioavailability of sirolimus via preparation of solid dispersion nanoparticles using a supercritical antisolvent process. Int J Nanomedicine 2011; 6:2997-3009. [PMID: 22162657 PMCID: PMC3230567 DOI: 10.2147/ijn.s26546] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The aim of this study was to improve the physicochemical properties and bioavailability of poorly water-soluble sirolimus via preparation of a solid dispersion of nanoparticles using a supercritical antisolvent (SAS) process. Methods First, excipients for enhancing the stability and solubility of sirolimus were screened. Second, using the SAS process, solid dispersions of sirolimus-polyvinylpyrrolidone (PVP) K30 nanoparticles were prepared with or without surfactants such as sodium lauryl sulfate (SLS), tocopheryl propylene glycol succinate, Sucroester 15, Gelucire 50/13, and Myrj 52. A mean particle size of approximately 250 nm was obtained for PVP K30-sirolimus nanoparticles. Solid state characterization, kinetic solubility, powder dissolution, stability, and pharmacokinetics were analyzed in rats. Results X-ray diffraction, differential scanning calorimetry, and high-pressure liquid chromatography indicated that sirolimus existed in an anhydrous amorphous form within a solid dispersion of nanoparticles and that no degradation occurred after SAS processing. The improved supersaturation and dissolution of sirolimus as a solid dispersion of nanoparticles appeared to be well correlated with enhanced bioavailability of oral sirolimus in rats. With oral administration of a solid dispersion of PVP K30-SLS-sirolimus nanoparticles, the peak concentration and AUC0→12h of sirolimus were increased by approximately 18.3-fold and 15.2-fold, respectively. Conclusion The results of this study suggest that preparation of PVP K30-sirolimus-surfactant nanoparticles using the SAS process may be a promising approach for improving the bioavailability of sirolimus.
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Affiliation(s)
- Min-Soo Kim
- College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea
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Ungell A, Artursson P. An Overview of Caco‐2 and Alternatives for Prediction of Intestinal Drug Transport and Absorption. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/9783527623860.ch7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Petri N, Lennernäs H. In Vivo
Permeability Studies in the Gastrointestinal Tract of Humans. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/9783527623860.ch9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sun H, Chow EC, Liu S, Du Y, Pang KS. The Caco-2 cell monolayer: usefulness and limitations. Expert Opin Drug Metab Toxicol 2008; 4:395-411. [PMID: 18433344 DOI: 10.1517/17425255.4.4.395] [Citation(s) in RCA: 317] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The Caco-2 monolayer has been used extensively for the high-throughput screening of drug permeability and identification of substrates, inhibitors, and inducers of intestinal transporters, especially P-glycoprotein (P-gp). Traditionally, the Caco-2 monolayer is viewed as a single barrier rather than a polarized cell monolayer consisting of metabolic enzymes that are sandwiched between two membrane barriers with distinctly different transporters. OBJECTIVE This review addressed the usefulness and limitations of the Caco-2 cell monolayer in drug discovery and mechanistic studies. METHODS This mini-review covered applications of the Caco-2 monolayer, clarified misconceptions, and critically addressed issues on data interpretation. CONCLUSION The catenary model extends the usefulness of Caco-2 monolayer and provides proper mechanistic insight and data interpretation.
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Affiliation(s)
- Huadong Sun
- University of Toronto, Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, Toronto, M5S 3M2, Canada +1 416 978 6164 ; +1 416 978 8511 ;
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Yengi LG, Leung L, Kao J. The Evolving Role of Drug Metabolism in Drug Discovery and Development. Pharm Res 2007; 24:842-58. [PMID: 17333392 DOI: 10.1007/s11095-006-9217-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 12/13/2006] [Indexed: 01/16/2023]
Abstract
Drug metabolism in pharmaceutical research has traditionally focused on the well-defined aspects of absorption, distribution, metabolism and excretion, commonly-referred to ADME properties of a compound, particularly in the areas of metabolite identification, identification of drug metabolizing enzymes (DMEs) and associated metabolic pathways, and reaction mechanisms. This traditional emphasis was in part due to the limited scope of understanding and the unavailability of in vitro and in vivo tools with which to evaluate more complex properties and processes. However, advances over the past decade in separate but related fields such as pharmacogenetics, pharmacogenomics and drug transporters, have dramatically shifted the drug metabolism paradigm. For example, knowledge of the genetics and genomics of DMEs allows us to better understand and predict enzyme regulation and its effects on exogenous (pharmacokinetics) and endogenous pathways as well as biochemical processes (pharmacology). Advances in the transporter area have provided unprecedented insights into the role of transporter proteins in absorption, distribution, metabolism and excretion of drugs and their consequences with respect to clinical drug-drug and drug-endogenous substance interactions, toxicity and interindividual variability in pharmacokinetics. It is therefore essential that individuals involved in modern pharmaceutical research embrace a fully integrated approach and understanding of drug metabolism as is currently practiced. The intent of this review is to reexamine drug metabolism with respect to the traditional as well as current practices, with particular emphasis on the critical aspects of integrating chemistry and biology in the interpretation and application of metabolism data in pharmaceutical research.
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Affiliation(s)
- Lilian G Yengi
- Drug Metabolism Division, Drug Safety and Metabolism, Wyeth Research, 500 Arcola Road, Collegeville, Pennsylvania 19426, USA.
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Leung LY, Lim HK, Abell MW, Zimmerman JJ. Pharmacokinetics and metabolic disposition of sirolimus in healthy male volunteers after a single oral dose. Ther Drug Monit 2006; 28:51-61. [PMID: 16418694 DOI: 10.1097/01.ftd.0000179838.33020.34] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The pharmacokinetics and metabolic disposition of sirolimus (rapamycin, Rapamune), a macrocyclic immunosuppressive agent for the prevention of allograft rejection in organ transplantation, were investigated in 6 healthy male volunteers after a single nominal 40-mg oral dose of the C-radiolabeled drug, with the added aim of assessing the potential role of sirolimus metabolites in the clinical pharmacology of the parent drug. The absorption of parent drug and derived materials was rapid (tmax 1.3 +/- 0.5 hours, mean +/- SD), and the elimination of sirolimus was slow (t(1/2) 60 +/- 10 hours, mean +/- SD) in whole blood. The high whole blood to plasma (B/P) concentration ratio of sirolimus (142 +/- 39) was consistent with its extensive partitioning into formed blood elements. The markedly lower B/P value based on radioactivity (2.7 +/- 0.4) suggested that drug-derived products partitioned into formed blood elements to a much lesser extent. Based on AUC0-144h values, unchanged sirolimus represented an average 35% of total radioactivity in whole blood. Drug-derived products in whole blood were characterized by HPLC, LC/MS, and LC/MS/MS as 41-O-demethyl, 7-O-demethyl, and several hydroxy, dihydroxy, hydroxy-demethyl and didemethyl sirolimus metabolites. The percentage distribution of sirolimus metabolites in whole blood ranged from 3%-10% at 1 hour to 6%-17% at 24 hours after drug administration. Based on their low immunosuppressive activities and relative abundance in whole blood of humans after sirolimus administration, metabolites of sirolimus do not appear to play a major role in the clinical pharmacology of the parent drug. A majority of the administered radioactivity (91.0 +/- 8.0%) was recovered from feces, and only 2.2% +/- 0.9% was renally excreted.
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Affiliation(s)
- Louis Y Leung
- Drug Safety and Metabolism, Wyeth Research, Collegeville, Pennsylvania 19426, USA.
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Hesselink DA, van Gelder T, van Schaik RH. The pharmacogenetics of calcineurin inhibitors: one step closer toward individualized immunosuppression? Pharmacogenomics 2006; 6:323-37. [PMID: 16004552 DOI: 10.1517/14622416.6.4.323] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The immunosuppressive drugs cyclosporin (CsA) and tacrolimus (Tac) are widely used to prevent acute rejection following solid-organ transplantation. However, the clinical use of these agents is complicated by their many side effects, a narrow therapeutic index and highly variable pharmacokinetics. The variability in CsA and Tac disposition has been attributed to interindividual differences in the expression of the metabolizing enzymes cytochrome P450 (CYP) 3A4 and 3A5, and in the expression of the drug transporter P-glycoprotein (encoded by the ABCB1 gene, formerly known as the multidrug resistance 1 gene). Variation in the expression of these genes could in turn be explained by several recently-identified single nucleotide polymorphisms (SNPs). Determination of these SNPs in (future) transplant recipients has the potential to identify individuals who are at risk of under-immunosuppression or the development of adverse drug reactions. Ultimately, genotyping for CYP3A and ABCB1 may lead to further individualization of immunosuppressive drug therapy for the transplanted patient.
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Affiliation(s)
- Dennis A Hesselink
- Erasmus MC, Department of Internal Medicine, Room Ee 563a, Renal Transplant Unit, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
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19
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Marty FM, Lowry CM, Cutler CS, Campbell BJ, Fiumara K, Baden LR, Antin JH. Voriconazole and Sirolimus Coadministration after Allogeneic Hematopoietic Stem Cell Transplantation. Biol Blood Marrow Transplant 2006; 12:552-9. [PMID: 16635790 DOI: 10.1016/j.bbmt.2005.12.032] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Accepted: 12/12/2005] [Indexed: 11/26/2022]
Abstract
Sirolimus is increasingly used in transplantation for prevention and treatment of graft-versus-host disease and organ rejection. Voriconazole is contraindicated when used concomitantly with sirolimus because of a substantial increase in sirolimus drug exposure with unadjusted dosing, but voriconazole is also considered the best initial treatment of invasive aspergillosis and other fungal infections. Patients who received voriconazole and sirolimus concomitantly were identified by a review of the medical records of all allogeneic hematopoietic stem cell recipients at our institution from September 1, 2002, to June 1, 2005. Data including baseline characteristics, indications for both drugs, and potential adverse effects were evaluated. Eleven patients received voriconazole and sirolimus concomitantly for a median of 33 days (range, 3-100 days). In 8 patients whose sirolimus dose was initially reduced by 90%, trough sirolimus levels were similar to those obtained before the administration of voriconazole; no obvious significant toxicity from either drug was observed during coadministration. Serious adverse events were observed in 2 patients in whom sirolimus dosing was not adjusted during voriconazole administration. Sirolimus and voriconazole may be safely coadministered if there is an empiric initial 90% sirolimus dose reduction combined with systematic monitoring of trough levels.
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Affiliation(s)
- Francisco M Marty
- Division of Infectious Diseases, Brigham & Women's Hospital, and Harvard Medical School, Boston, Massachusetts 02115, USA.
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20
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Liu Y, Hunt CA. Mechanistic study of the cellular interplay of transport and metabolism using the synthetic modeling method. Pharm Res 2006; 23:493-505. [PMID: 16435171 DOI: 10.1007/s11095-006-9505-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Accepted: 11/14/2005] [Indexed: 11/25/2022]
Abstract
PURPOSE The aims of this study were 1) to demonstrate a new modeling strategy that uses experimental computational models built by the synthetic method and 2) to study the consequences of spatial alignment, or lack thereof, of P-glycoprotein (Pgp) and CYP3A4 on the transport and metabolism of drug-like compounds and the influence of competitive inhibition by metabolites on the transport and metabolism of those compounds. METHODS The synthetic method of modeling and simulation was used to construct discrete-event, discrete-space models. Within a framework designed for experimentation, object-oriented software components were assembled into devices representing the efflux transport and metabolism mechanisms within cell monolayers in Caco-2 transwell systems. RESULTS Conditions for transport and metabolism synergism (and lack thereof) were identified. Simulations showed how spatial alignment altered the coordinated influences of Pgp and CYP3A4 on absorption of a series of drug-like compounds. Within those experiments, when the metabolites were also substrates of Pgp, the metabolite levels produced were insufficient to give evidence of a competitive inhibitory effect on either transport or metabolism. CONCLUSIONS The results provide evidence of the potential value of using this class of models to improve our understanding of how complex cellular processes influence the transport and absorption of compounds, and the consequences of interventions.
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Affiliation(s)
- Yu Liu
- The UCSF/UCB Joint Graduate Group in Bioengineering, University of California, Berkeley, California, USA
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21
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Abstract
A basic tenet of clinical pharmacology is that the pharmacologic activity of an exogenously administered agent is related to the free drug concentration available at its receptor or ligand-binding site. The discipline of pharmacokinetics can be defined as the study of the processes that lead to the availability of an agent to its site of action. In this review we will discuss basic principles of pharmacokinetics that govern the absorption, distribution, metabolism, elimination and binding of immunosuppressive drugs commonly utilized in whole organ transplantation. In a discipline such as organ transplantation, where the agents utilized carry significant toxicity and where failure of efficacy can have dire consequences, knowledge of the pharmacokinetics of the agents utilized has become a basic skill for all transplant professionals. In this review we describe some of the underlying principles that govern the disposition of the agents commonly utilized in solid organ transplantation. In addition, we hope this review will help in understanding some of the basic drug interactions encountered in transplant practice.
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Affiliation(s)
- Titte R Srinivas
- Department of Medicine, University of Florida, Gainesville, Florida, USA
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22
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Paine MF, Ludington SS, Chen ML, Stewart PW, Huang SM, Watkins PB. Do men and women differ in proximal small intestinal CYP3A or P-glycoprotein expression? Drug Metab Dispos 2004; 33:426-33. [PMID: 15608139 DOI: 10.1124/dmd.104.002469] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The higher systemic clearance of some CYP3A4 [whether also P-glycoprotein (P-gp)] drug substrates in women versus men is attributed in part to a higher hepatic CYP3A4 content in women. This, combined with the general paucity of reported sex differences in the apparent oral clearance of CYP3A4 substrates, suggested a sex-dependent expression of CYP3A4 in the intestine, but in a pattern opposite to that in the liver. Accordingly, duodenal biopsies obtained from healthy men (n = 46) and women (n = 45) were analyzed, by Western blot, for relative CYP3A4, as well as for CYP3A5 and P-gp, expression levels. Among all subjects, CYP3A4 and P-gp varied 8- and 10-fold, respectively. CYP3A5, which was readily detected in 27% of these predominantly white individuals, varied 7-fold. For all three proteins, a sex difference was not detected (p >/= 0.55). The lack of a difference remained for CYP3A4 and P-gp when the analysis was restricted to white individuals (n = 74) or to individuals with undetectable CYP3A5. Comparing the 21 premenopausal women (all were aged <45 years) with the 43 men aged <45 years, again no sex differences were detected in CYP3A4 and P-gp. Comparing the pre- with postmenopausal women, mean CYP3A4 content was 20% lower in the postmenopausal individuals (p = 0.01). The lack of a sex-dependent difference in proximal intestinal CYP3A4 could account, in part, for the lack of reported sex differences in the oral, relative to systemic, clearance of some CYP3A4 substrates. Ramifications of lower intestinal CYP3A4 content in post- versus premenopausal women require further investigation.
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Affiliation(s)
- Mary F Paine
- General Clinical Research Center, Room 3005, Bldg. APCF, CB# 7600, UNC Hospitals, Chapel Hill, NC 27599-7600, USA.
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23
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Paine MF, Criss AB, Watkins PB. Two Major Grapefruit Juice Components Differ in Time to Onset of Intestinal CYP3A4 Inhibition. J Pharmacol Exp Ther 2004; 312:1151-60. [PMID: 15485894 DOI: 10.1124/jpet.104.076836] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Grapefruit juice elevates blood levels of some drugs taken orally, primarily by inhibiting intestinal CYP3A4-mediated first-pass metabolism. Two prominent furanocoumarins in the juice, 6',7'-dihydroxybergamottin (DHB) and bergamottin (BG), have been demonstrated as important contributors to grapefruit juice-drug interactions. Using CYP3A4-expressing Caco-2 cells and representative probes from distinct CYP3A4 substrate subgroups (midazolam, testosterone), we compared the time-dependent inhibitory properties of DHB and BG. DHB rapidly inhibited CYP3A4 activity in a substrate-independent fashion with maximal inhibition (>/=85%) generally occurring within 30 min. In contrast, BG had a slower onset and exhibited substrate-dependent inhibition. Whereas testosterone 6beta-hydroxylation was inhibited by >50% with all exposure times (0.5-3 h), midazolam 1'-hydroxylation was unaffected, or even activated, with short exposure times (<1 h). After a 3-h exposure, however, BG had begun to "catch up" with DHB, causing >/=70% inhibition, independent of substrate. Likewise, loss of CYP3A4 protein, believed to reflect rapid intracellular degradation of the enzyme following mechanism-based inactivation, was comparable between the furanocoumarins (40-50%). The time course of BG-mediated inhibition was similar after just a 30-min exposure, indicating that the short exposure presumed to occur after juice ingestion is sufficient to initiate the events required to cause substantial inhibition (>/=50%). These results suggest that after ingestion of a glass of grapefruit juice, CYP3A4 is maximally inhibited by DHB before BG has the opportunity to act. However, foods containing BG but not DHB (e.g., lime juice) could produce a substrate-dependent interaction with drugs consumed concomitantly, but a substrate-independent interaction with drugs taken several hours after food consumption.
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Affiliation(s)
- Mary F Paine
- General Clinical Research Center, Room 3005 Bldg. APCF, CB# 7600, UNC Hospitals, Chapel Hill, NC 27599-7600, USA.
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24
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Abstract
Sirolimus is a recently marketed immunosuppressant that, in common with cyclosporine and tacrolimus, exhibits a low average oral bioavailability (approximately 20%). Likewise, sirolimus is a substrate for the major drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) and the efflux transporter P-glycoprotein (P-gp), both of which are expressed in close proximity in epithelial cells lining the small intestine. Using CYP3A4-expressing Caco-2 cell monolayers, we examined the interplay between metabolism and transport on the intestinal first-pass extraction of sirolimus. Modified Caco-2 cells metabolized [14C]sirolimus to the same CYP3A4-mediated metabolites as human small intestinal and liver microsomes. [14C]Sirolimus also degraded to the known ring-opened product, seco-sirolimus. A ring-opened dihydro species (M2) was, surprisingly, the major product detected in cells at all sirolimus concentrations examined (2-100 micromol/L) and in incubations with human liver and intestinal homogenates but not in corresponding microsomes. M2 formation was NADPH-dependent but unaffected by prototypical CYP3A4 inhibitors. Although M2 was formed from purified seco-sirolimus (20 micromol/L) in the homogenates, it was not detected in cells when seco-sirolimus was added to the apical compartment because seco-sirolimus was essentially impermeable to the apical membrane. Sirolimus, seco-sirolimus (basolaterally dosed), and M2 were all secreted across the apical membrane, and secretion of each was inhibited by the P-gp inhibitor LY335979 (zosuquidar trihydrochloride). Along with CYP3A4-mediated metabolism and P-gp-mediated efflux, a novel elimination pathway was identified that may also contribute to the first-pass extraction, and hence low oral bioavailability, of sirolimus. This new insight into the intestinal elimination of sirolimus, which was not identified using traditional drug metabolism/transport screening methods, may represent another source for the limited absorption of sirolimus.
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Affiliation(s)
- Mary F Paine
- General Clinical Research Center and Division of Pharmacotherapy, University of North Carolina, Chapel Hill, North Carolina 27599-7600, USA.
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25
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Abstract
PURPOSE The contribution of the efflux transporter P-glycoprotein (P-gp) as a barrier to drug absorption may depend on its level of expression at the site of absorption. Accordingly, the distribution of P-gp was examined along the entire length of the human small intestine. METHODS Homogenates prepared from mucosal scrapings from every other 30-cm segment of four unrelated human donor small intestines were analyzed for P-gp and the control protein villin by Western blot. RESULTS In each donor intestine, relative P-gp expression (P-gp/villin integrated optical density ratio) progressively increased from proximal to distal regions. Among individuals, relative P-gp levels varied 2.1-fold in the duodenal/proximal jejunal region, 1.5- to 2.0-fold in the middle/distal jejunal region, and 1.2- to 1.9-fold in the ileal region. Within-donor variation was somewhat greater, from 1.5- to 3.0-fold. CONCLUSIONS These results provide further evidence that the site of absorption can represent another source for the interindividual variation in the oral bioavailability of drugs.
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Affiliation(s)
- Stéphane Mouly
- Hopital Lariboisiere, Service de Medecine Interne A, 75475 Paris Cedex 10, France
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26
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Fredericks S, Holt DW, MacPhee IAM. The pharmacogenetics of immunosuppression for organ transplantation: a route to individualization of drug administration. ACTA ACUST UNITED AC 2004; 3:291-301. [PMID: 14575518 DOI: 10.2165/00129785-200303050-00001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Transplantation has transformed the treatment of patients with organ failure in a number of clinical settings, and immunosuppressive drug therapy is fundamental to its success. However, all the drugs in current use have a narrow therapeutic index. Under-dosing can lead to rejection, while over-dosing increases the risks of infection, malignant disease, and serious drug-specific adverse effects, including diabetes mellitus, nephrotoxicity, hypertension, and hyperlipidemia. Heterogeneity in the pharmacokinetics of these drugs makes initial dose determination difficult, as there is a poor correlation between dose and blood concentration. This results in difficulties in achieving target blood concentrations early after transplantation, which are important for reducing the rate of immunological rejection. This problem is compounded by the observation that neither drug dose nor drug blood concentration accurately predict clinical efficacy or toxicity. The main determinant of heterogeneity in dose requirements is intestinal absorption of the active drug. The oxidative enzymes, cytochrome P450 (CYP) 3A4 and CYP3A5, and the drug efflux pump P-glycoprotein (P-gp) in enterocytes regulate this process. Most substrates for the P-gp pump are also substrates for the CYP3A enzymes. An efficient barrier to xenobiotic absorption is formed by the CYP enzymes and P-gp, and by the two systems working synergistically. Genetic polymorphisms have been reported for the genes associated with the expression of the CYP3A enzymes and P-gp. Genotyping patients for CYP3A genes has the potential to aid the establishment of optimal dosage regimens for transplant patients. Genetic polymorphism of the multiple drug resistance gene-1 (MDR1, also known as ABCB1) [3435C/T] and the CYP3A5 genes (CYP3A5*1, CYP3AP1*1) have the greatest potential to influence the pharmacokinetics of immunosuppressants. Homozygosity of the T allele of the MDR1 3435C/T polymorphism has been associated with reduced enterocyte expression of P-gp resulting in increased drug absorption. The presence of the CYP3A5*1 allele is necessary for the production of a fully catalytic CYP3A5 protein, and also influences the ratio of CYP3A4 : CYP3A5 as well as the overall CYP3A catalytic activity. The CYP3A4 : CYP3A5 ratio may, in turn, influence the pattern of drug metabolites formed. Heterogeneity in the production of active and inactive metabolites has implications for both the pharmacokinetics and pharmacodynamics of these drugs.Gene frequencies and drug dose requirements differ between ethnic groups. Ethnic differences in dose requirements for immunosuppressants have been discussed widely. However, ethnicity is a rather crude marker for genotype. Pharmacogenetic typing offers the possibility of significant improvement in the individualization of immunosuppressive drug prescribing with reduced rates of rejection and toxicity.
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Affiliation(s)
- Salim Fredericks
- Department of Cardiovascular Medicine, Analytical Unit, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
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27
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Mouly SJ, Paine MF, Watkins PB. Contributions of CYP3A4, P-glycoprotein, and Serum Protein Binding to the Intestinal First-Pass Extraction of Saquinavir. J Pharmacol Exp Ther 2004; 308:941-8. [PMID: 14718607 DOI: 10.1124/jpet.103.056390] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Using CYP3A4-expressing Caco-2 cell monolayers, we assessed the roles of CYP3A4-mediated metabolism, P-glycoprotein (P-gp)-mediated efflux, and serum protein binding in determining the extent of the intestinal first-pass extraction (E(i)) of saquinavir. Saquinavir (5-40 microM) was added to the apical compartment of culture inserts. After 3 h, apical and basolateral media and cell scrapings were analyzed for saquinavir and a major CYP3A4-mediated metabolite (M7). The intracellular concentration of saquinavir was estimated from the degree of inhibition of CYP3A4 catalytic activity (midazolam 1'-hydroxylation). Compared with vehicle, the P-gp inhibitor LY335979 (zosuquidar trihydrochloride) (0.5 microM, apical) increased saquinavir cell content and M7 formation rate, but decreased the E(i) by approximately 50% due to a >90% increase in the amount of saquinavir recovered in the basolateral compartment. Compared with LY335779, physiological concentrations of basolateral serum proteins [human serum albumin and alpha1-acid glycoprotein (AAG)] increased saquinavir permeability by a similar degree but decreased the E(i) by approximately 50% due to a marked reduction in M7 formation. Increasing AAG concentration (1.0-2.5 g/l) had no additional effect on permeability or E(i). An estimate of the range of the E(i) of saquinavir (7-60%) was less than has been predicted based on in vitro data (>99%) but was consistent with a clinical study involving grapefruit juice. The incidental finding of greater M7 formation after basolateral compared with apical dosing could not be explained by differences in saquinavir cell content. We conclude that variable intestinal first-pass extraction of saquinavir in human immunodeficiency virus-infected patients could reflect variation in P-gp-mediated efflux and/or CYP3A4-catalyzed metabolism, but not in blood AAG levels.
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Affiliation(s)
- Stéphane J Mouly
- General Clinical Research Center, University of North Carolina Hospitals, Chapel Hill, NC 27599-7600, USA
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28
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Pang KS. MODELING OF INTESTINAL DRUG ABSORPTION: ROLES OF TRANSPORTERS AND METABOLIC ENZYMES (FOR THE GILLETTE REVIEW SERIES). Drug Metab Dispos 2003; 31:1507-19. [PMID: 14625347 DOI: 10.1124/dmd.31.12.1507] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- K Sandy Pang
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
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29
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Cummins CL, Jacobsen W, Christians U, Benet LZ. CYP3A4-transfected Caco-2 cells as a tool for understanding biochemical absorption barriers: studies with sirolimus and midazolam. J Pharmacol Exp Ther 2003; 308:143-55. [PMID: 14569063 DOI: 10.1124/jpet.103.058065] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
CYP3A4-transfected Caco-2 cells were used as an in vitro system to predict the importance of drug metabolism and transport on overall drug absorption. We examined the transport and metabolism of two drugs; midazolam, an anesthetic agent and CYP3A4 substrate, and sirolimus, an immunosuppressant and a dual CYP3A4/P-glycoprotein (P-gp) substrate, in the presence of cyclosporine (CsA, a CYP3A4/P-gp inhibitor) or N-[4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)-ethyl]-phenyl]-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamine (GG918) (an inhibitor of P-gp and not CYP3A4). All major CYP3A4 metabolites were formed in the cells (1-OH > 4-OH midazolam and 39-O-desmethyl > 12-OH > 11-OH sirolimus), consistent with results from human liver microsomes. There was no bidirectional transport of midazolam across CYP3A4-transfected Caco-2 cells, whereas there was a 2.5-fold net efflux of sirolimus (1 microM) that disappeared in the presence of CsA or GG918. No change in the absorption rate or extraction ratio (ER) for midazolam was observed when P-gp was inhibited with GG918. Addition of GG918 had a modest impact on the absorption rate and ER for sirolimus (increased 58% and decreased 25%, respectively), whereas a 6.1-fold increase in the absorption rate and a 75% decrease in the ER were found when sirolimus was combined with CsA. Although both midazolam and sirolimus metabolites were preferentially excreted to the apical compartment, only sirolimus metabolites were transported by P-gp as determined from inhibition studies with GG918. Using CYP3A4-transfected Caco-2 cells we determined that, in contrast to P-gp, CYP3A4 is the major factor limiting sirolimus absorption. The integration of CYP3A4 and P-gp into a combined in vitro system was critical to unveil the relative importance of each biochemical barrier.
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Affiliation(s)
- Carolyn L Cummins
- Department of Biopharmaceutical Sciences, University of California San Francisco, San Francisco, California 94143-0446, USA
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30
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Tam D, Sun H, Pang KS. Influence of P-glycoprotein, transfer clearances, and drug binding on intestinal metabolism in Caco-2 cell monolayers or membrane preparations: a theoretical analysis. Drug Metab Dispos 2003; 31:1214-26. [PMID: 12975330 DOI: 10.1124/dmd.31.10.1214] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studies on the Caco-2 cell monolayer system that contained cytochrome P450 and P-glycoprotein activities had advanced the theory that increased intestinal metabolism resulted with increased drug efflux due to an increase in mean residence time (MRT) in the system. To confirm or refute the claim, we developed compartmental models to study the effects of intestinal secretion on the MRT and rates of metabolism under first-order and nonlinear conditions. The theoretical examinations showed that under first-order conditions, intestinal secretion increased the MRT of drug in all compartments but failed to increase the rate of metabolite formation or the total amount of metabolite formed. Instead, reduced metabolic rates arose with increased efflux from cell, either into the apical or the basolateral compartment. By contrast, under saturable metabolic conditions, there were some conditions found whereby rates of metabolism increased with intestinal secretion and rapid reabsorption, albeit the total amount of metabolite formed eventually equaled the administered dose. Intestinal secretion failed to induce higher rates of metabolism for other conditions (saturable cellular binding, cellular efflux, or cell entry). With saturation of metabolic enzymes, drug efflux brought about desaturation, and, upon rapid recovery of drug into the cellular compartment, higher rates of metabolite formation were attained. The simulation study showed that, under first-order conditions, intestinal secretion reduced the rate of metabolism even though the MRT was prolonged within the cell preparation. With nonlinear metabolism, however, instances may exist whereby higher rates of metabolism would result with secretion.
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Affiliation(s)
- Debbie Tam
- Faculty of Pharmacy, University of Toronto, 19 Russell Street, Ontario, Canada M5S 2S2.
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31
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Troutman MD, Thakker DR. Novel experimental parameters to quantify the modulation of absorptive and secretory transport of compounds by P-glycoprotein in cell culture models of intestinal epithelium. Pharm Res 2003; 20:1210-24. [PMID: 12948019 DOI: 10.1023/a:1025001131513] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The purpose of this work was to elucidate the asymmetric effect of P-gp on modulation of absorptive and secretory transport of compounds across polarized epithelium, to develop experimental parameters to quantify P-gp-mediated modulation of absorptive and secretory transport, and to elucidate how P-gp-mediated modulation of transport is affected by passive diffusion properties, interaction of the substrate with P-gp, and P-gp expression. METHODS The permeability of a set of P-gp substrates was determined in absorptive and secretory directions in Madine-Darby Canine kidney (MDCK), Caco-2, and MDR-MDCK monolayers. The transport was also determined in the presence of GW918, a non-competitive P-gp inhibitor, to quantify the permeability without the influence of P-gp. From these two experimental permeability values in each direction, two new parameters, absorptive quotient (AQ) and the secretory quotient (SQ), were defined to express the functional activity of P-gp during absorptive and secretory transport, respectively. Western blot analysis was used to quantify P-gp expression in these monolayers and in normal human intestinal. RESULTS P-gp expression in Caco-2 and MDR-MDCK monolayers was comparable to that in normal intestine, and much less in MDCK cells. For all models, the substrates encompassed a wide range of apparent permeability due to passive diffusion (PPD). The parameters AQ and SQ, calculated for all compounds, assessed the attenuation in absorptive and enhancement of secretory transport, respectively, normalized to the permeability due to passive diffusion. Analysis of these parameters showed that 1) P-gp affected absorptive and secretory transport differentially and 2) compounds could be stratified into distinct groups with respect to the modulation of their absorptive and secretory transport by P-gp. Compounds could be identified whose absorptive transport was either strongly affected or poorly affected by changes in P-gp expression. For certain compounds, AQ values showed parabolic relationship with respect to passive diffusivity, and for others AQ was unaffected by changes in passive diffusivity. CONCLUSIONS The relationship between attenuation of absorptive transport and enhancement of secretory transport of compounds by P-gp is asymmetric, and different for different sets of compounds. The relationship between attenuation of absorption by P-gp and passive diffusivity of compounds, their interaction potential with P-gp, and levels of P-gp expression is complex; however, compounds can be classified into sets based on these relationships. A classification system that describes the functional activity of P-gp with respect to modulation of absorptive and secretory transport was developed from these results.
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Affiliation(s)
- Matthew D Troutman
- Division of Drug Delivery and Disposition, School of Pharmacy, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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