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Gebauer L, Jensen O, Rafehi M, Brockmöller J. Stereoselectivity in Cell Uptake by SLC22 Organic Cation Transporters 1, 2, and 3. J Med Chem 2023; 66:15990-16001. [PMID: 38052451 PMCID: PMC10726348 DOI: 10.1021/acs.jmedchem.3c01436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 10/30/2023] [Accepted: 11/24/2023] [Indexed: 12/07/2023]
Abstract
Stereoselectivity can be most relevant in drug metabolism and receptor binding. Although drug membrane transport might be equally important for small-molecule pharmacokinetics, the extent of stereoselectivity in membrane transport is largely unknown. Here, we characterized the stereoselective transport of 18 substrates of SLC22 organic cation transporters (OCTs) 1, 2, and 3. OCT2 and OCT3 showed highly stereoselective cell uptake with several substrates and, interestingly, often with opposite stereoselectivity. In contrast, transport by OCT1 was less stereoselective, although (R)-tamsulosin was transported by OCT1 with higher apparent affinity than the (S)-enantiomer. Using OCT1 and CYP2D6 co-overexpressing cells, an additive effect of the stereoselectivities was demonstrated. This indicates that pharmacokinetic stereoselectivity may be the result of combined effects in transport and metabolism. This study highlights that the pronounced polyspecificity of OCTs not contradicts stereoselectivity in the transport. Nevertheless, stereoselectivity is highly substrate-specific and for most substrates and OCTs, there was no major selectivity.
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Affiliation(s)
- Lukas Gebauer
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Ole Jensen
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Muhammad Rafehi
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
| | - Jürgen Brockmöller
- Institute of Clinical Pharmacology, University Medical Center Göttingen, Göttingen D-37075, Germany
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Jensen O, Rafehi M, Tzvetkov MV, Brockmöller J. Stereoselective cell uptake of adrenergic agonists and antagonists by organic cation transporters. Biochem Pharmacol 2020; 171:113731. [DOI: 10.1016/j.bcp.2019.113731] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/22/2019] [Indexed: 10/25/2022]
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Jacobson GA, Hostrup M, Narkowicz CK, Nichols DS, Walters EH. Enantioselective disposition of (R,R)-formoterol, (S,S)-formoterol and their respective glucuronides in urine following single inhaled dosing and application to doping control. Drug Test Anal 2019; 11:950-956. [PMID: 30865387 DOI: 10.1002/dta.2587] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 12/17/2022]
Abstract
Formoterol is a long-acting beta2-adrenoceptor agonist (LABA) used for the treatment of asthma and exercise-induced bronchoconstriction. Formoterol is usually administered as a racemic (rac-) mixture of (R,R)- and (S,S)-enantiomers. While formoterol is restricted by the World Anti-Doping Agency (WADA), inhalation of formoterol is permitted to a predetermined dose (54 μg/24 hours) and a urine threshold of 40 ng/mL. However, chiral switch enantiopure (R,R)-formoterol is available, effectively doubling the therapeutic advantage for the same threshold. The aim of this study was to investigate whether formoterol exhibits enantioselective urinary pharmacokinetics following inhalation. Six healthy volunteers were administered a 12 μg inhaled dose of rac-formoterol. Urine was collected over 24 hours and analyzed by enantioselective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay. Total (free drug plus conjugated metabolite) median (min-max) rac-formoterol urine levels following inhalation were 1.96 (1.05-13.4) ng/mL, 1.67 (0.16-9.67) ng/mL, 0.45 (0.16-1.51) ng/mL, 0.61 (0.33-0.78) ng/mL, and 0.17 (0.08-1.06) ng/mL at 2, 4, 8, 12, and 24 hours, respectively, well below the 2019 urine threshold. The proportion of conjugation differed between enantiomers with glucuronide conjugation much greater for (R,R)-formoterol (around 30%-60% of total) compared to (S,S)-formoterol (0%-30%). There was clear evidence of inter-individual enantioselectivity observed in the ratios of (R,R):(S,S)-formoterol, where (S,S)- was predominant in free formoterol, and (R,R)- predominant in the conjugated metabolite. In conclusion, rac-formoterol delivered by inhalation exhibits enantioselective elimination in urine following single-dose administration. Enantioselective assays should be employed in doping control to screen for banned beta2-agonist chiral switch products such as (R,R)-formoterol, and total hydrolyzed rac-formoterol is warranted to account for inter-individual differences in enantioselective glucuronidation.
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Affiliation(s)
| | - Morten Hostrup
- Section of Integrative Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.,Department of Respiratory Medicine, Bispebjerg University Hospital, Denmark
| | | | - David S Nichols
- Central Science Laboratory, University of Tasmania, Hobart, Australia
| | - E Haydn Walters
- School of Medicine, University of Tasmania, Hobart, Australia
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Shen Z, Lv C, Zeng S. Significance and challenges of stereoselectivity assessing methods in drug metabolism. J Pharm Anal 2016; 6:1-10. [PMID: 29403956 PMCID: PMC5762452 DOI: 10.1016/j.jpha.2015.12.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 12/21/2015] [Accepted: 12/21/2015] [Indexed: 12/14/2022] Open
Abstract
Stereoselectivity in drug metabolism can not only influence the pharmacological activities, tolerability, safety, and bioavailability of drugs directly, but also cause different kinds of drug-drug interactions. Thus, assessing stereoselectivity in drug metabolism is of great significance for pharmaceutical research and development (R&D) and rational use in clinic. Although there are various methods available for assessing stereoselectivity in drug metabolism, many of them have shortcomings. The indirect method of chromatographic methods can only be applicable to specific samples with functional groups to be derivatized or form complex with a chiral selector, while the direct method achieved by chiral stationary phases (CSPs) is expensive. As a detector of chromatographic methods, mass spectrometry (MS) is highly sensitive and specific, whereas the matrix interference is still a challenge to overcome. In addition, the use of nuclear magnetic resonance (NMR) and immunoassay in chiral analysis are worth noting. This review presents several typical examples of drug stereoselective metabolism and provides a literature-based evaluation on current chiral analytical techniques to show the significance and challenges of stereoselectivity assessing methods in drug metabolism.
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Affiliation(s)
- Zhuowei Shen
- Institute of Drug Metabolism and Pharmaceutical Analysis, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Chuang Lv
- Biogen Idec, Cambridge, MA 02142, USA
| | - Su Zeng
- Institute of Drug Metabolism and Pharmaceutical Analysis, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
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Kutsuno Y, Itoh T, Tukey RH, Fujiwara R. Glucuronidation of drugs and drug-induced toxicity in humanized UDP-glucuronosyltransferase 1 mice. Drug Metab Dispos 2014; 42:1146-52. [PMID: 24764149 DOI: 10.1124/dmd.114.057083] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
UDP-glucuronosyltransferases (UGTs) are phase II drug-metabolizing enzymes that catalyze glucuronidation of various drugs. Although experimental rodents are used in preclinical studies to predict glucuronidation and toxicity of drugs in humans, species differences in glucuronidation and drug-induced toxicity have been reported. Humanized UGT1 mice in which the original Ugt1 locus was disrupted and replaced with the human UGT1 locus (hUGT1 mice) were recently developed. In this study, acyl-glucuronidations of etodolac, diclofenac, and ibuprofen in liver microsomes of hUGT1 mice were examined and compared with those of humans and regular mice. The kinetics of etodolac, diclofenac, and ibuprofen acyl-glucuronidation in hUGT1 mice were almost comparable to those in humans, rather than in mice. We further investigated the hepatotoxicity of ibuprofen in hUGT1 mice and regular mice by measuring serum alanine amino transferase (ALT) levels. Because ALT levels were increased at 6 hours after dosing in hUGT1 mice and at 24 hours after dosing in regular mice, the onset pattern of ibuprofen-induced liver toxicity in hUGT1 mice was different from that in regular mice. These data suggest that hUGT1 mice can be valuable tools for understanding glucuronidations of drugs and drug-induced toxicity in humans.
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Affiliation(s)
- Yuki Kutsuno
- School of Pharmacy, Kitasato University, Tokyo, Japan (Y.K., T.I., R.F.); and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Tomoo Itoh
- School of Pharmacy, Kitasato University, Tokyo, Japan (Y.K., T.I., R.F.); and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Robert H Tukey
- School of Pharmacy, Kitasato University, Tokyo, Japan (Y.K., T.I., R.F.); and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
| | - Ryoichi Fujiwara
- School of Pharmacy, Kitasato University, Tokyo, Japan (Y.K., T.I., R.F.); and Laboratory of Environmental Toxicology, Department of Pharmacology, University of California San Diego, La Jolla, California (R.H.T.)
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Lampinen Salomonsson M, Bondesson U, Hedeland M. In vitro formation of phase I and II metabolites of propranolol and determination of their structures using chemical derivatization and liquid chromatography-tandem mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2009; 44:742-754. [PMID: 19170146 DOI: 10.1002/jms.1551] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Derivatization with 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) has been successfully used as a tool to differentiate between aromatic and aliphatic O-glucuronides of hydroxypropranolol. The analyses were performed with liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) with both a triple quadrupole and an ion trap instrument. Hydroxylated forms of propranolol can be glucuronidated in aliphatic as well as aromatic positions. These isoforms are not distinguishable by tandem MS alone, as they both initially lose 176 Da, i.e. monodehydrated glucuronic acid, giving back the aglycone. Two in vitro systems were set up for the production of propranolol metabolites. The obtained isomers of 4'-hydroxypropranolol glucuronide were determined to correspond to one aliphatic and one aromatic form, using chemical derivatization with DMISC and LC-MS(n). DMISC was shown to react with the secondary amine in the case where the naphtol was occupied by the glucuronyl moiety, resulting in a different fragmentation pattern compared with that of the aliphatic glucuronide, where the naphtol group was accessible to derivatization.
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Affiliation(s)
- Matilda Lampinen Salomonsson
- Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, SE-751 23 Uppsala, Sweden.
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Salomonsson ML, Bondesson U, Hedeland M. Structural evaluation of the glucuronides of morphine and formoterol using chemical derivatization with 1,2-dimethylimidazole-4-sulfonyl chloride and liquid chromatography/ion trap mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:2685-2697. [PMID: 18677706 DOI: 10.1002/rcm.3667] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
For the first time chemical derivatization of isomeric drug glucuronides with 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) has been successfully applied as a tool for determining the site of conjugation. This provides a way to differentiate between glucuronide isomers containing aliphatic and phenolic hydroxyl groups. The analyses were performed with liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI-MSn). DMISC has previously been shown to react selectively with phenols in estrogens, thus improving sensitivity in ESI-MS. The model compounds selected for this study were commercially available standards of formoterol, morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G). Formoterol glucuronides were produced with an enzymatic method in house. Both formoterol and morphine possess one phenolic and one aliphatic hydroxyl group where glucuronidation could take place. The product ion mass spectra of the native morphine glucuronides were indistinguishable due to the initial neutral loss of monodehydrated glucuronic acid (176 u). However, a significant difference between the isomers was observed with DMISC derivatization, as only the form with a free phenol, M6G, gave a detectable reaction product. Formoterol formed two detectable glucuronide isomers in the enzymatic reaction. Their respective sites of conjugation could not be directly determined from the product ion spectra. Reaction with DMISC, however, gave a detectable product with only one of the isomers. Based on previous experience of the preferred DMISC reactions with phenols, and interpretation of the fragmentation pattern of the derivative, it was concluded that the reactive isomer had a free phenol, and was thus conjugated on the aliphatic chain.
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Affiliation(s)
- Matilda Lampinen Salomonsson
- Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, P.O. Box 574, SE-751 23 Uppsala, Sweden
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Felix G, Berthod A. Part II: From Dermatologicals to Sensory Organ and Various Drugs. SEPARATION AND PURIFICATION REVIEWS 2008. [DOI: 10.1080/15422110701873007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Many chiral drugs are used as their racemic mixtures in clinical practice. Two enantiomers of a chiral drug generally differ in pharmacodynamic and/or pharmacokinetic properties as a consequence of the stereoselective interaction with optically active biological macromolecules. Thus, a stereospecific assay to discriminate between enantiomers is required in order to relate plasma concentrations to pharmacological effect of a chiral drug. Stereoselective metabolism of drugs is most commonly the major contributing factor to stereoselectivity in pharmacokinetics. Metabolizing enzymes often display a preference for one enantiomer of a chiral drug over the other, resulting in enantioselectivity. The structural characteristics of enzymes dictate the enantiomeric discrimination associated with the metabolism of chiral drugs. The stereoselectivity can, therefore, be viewed as the physical property characteristic that phenotypes the enzyme. This review provides a comprehensive appraisal of stereochemical aspects of drug metabolism (i.e., enantioselective metabolism and first-pass effect, enzyme-selective inhibition or induction and drug interaction, species differences and polymorphic metabolism).
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Affiliation(s)
- Hong Lu
- GlaxoSmithKline, Worldwide Drug Metabolism and Pharmacokinetics, 5 Moore Drive, Research Triangle Park, NC 27709-3398, USA.
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Somers GI, Lindsay N, Lowdon BM, Jones AE, Freathy C, Ho S, Woodrooffe AJM, Bayliss MK, Manchee GR. A Comparison of the Expression and Metabolizing Activities of Phase I and II Enzymes in Freshly Isolated Human Lung Parenchymal Cells and Cryopreserved Human Hepatocytes. Drug Metab Dispos 2007; 35:1797-805. [PMID: 17627976 DOI: 10.1124/dmd.107.015966] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pulmonary and hepatic expression and catalytic activities of phase I and II drug-metabolizing enzymes were compared using human lung and liver tissue, and lung parenchymal cells (LPCs) and cryopreserved hepatocytes. Cytochrome P450 gene expression was generally lower in lung than in liver and CYP3A4 expression in lung was negligible. Esterase gene expression was similar in lung and liver. Expression of all sulfotransferase isoforms in lung was similar to or higher than that in liver. Lung tissue expressed low levels of UGT. However, the expression of UGT2A1 in lung was higher than that in liver. There was a range of catalytic activities in LPCs, including cytochrome P450, esterase, and sulfation pathways. Phase I activities were generally less than 10% of those determined in hepatocytes. Rates of ester hydrolysis and sulfation in LPCs were similar to those in hepatocytes. When measurable, glucuronidation in LPCs was present at very low levels, reflecting the gene expression data. The metabolism of salbutamol, formoterol, and budesonide was also investigated. Production of salbutamol-4-O-sulfate and budesonide oleate was observed in LPCs from at least two of three donor preparations studied. Formoterol sulfate and low levels of formoterol glucuronide were detected in one of three donors. In general, drug-metabolizing capability of LPCs is low compared with liver, although some evidence for substantial sulfation and deesterification capacity was observed. Therefore, these data support the use of this cell-based system for the investigation of key routes of xenobiotic metabolism in human lung parenchyma.
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Affiliation(s)
- G I Somers
- Drug Metabolism and Pharmacokinetics, Respiratory and Inflammation Centre of Excellence for Drug Discovery, GlaxoSmithKline, Stevenage, UK.
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Cazzola M, Matera MG, Lötvall J. Ultra long-acting beta 2-agonists in development for asthma and chronic obstructive pulmonary disease. Expert Opin Investig Drugs 2006; 14:775-83. [PMID: 16022567 DOI: 10.1517/13543784.14.7.775] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
After the discovery of formoterol and salmeterol, new candidates for long-acting beta2-adrenoceptor agonists (LABAs) have emerged from various companies. In particular, once-daily beta2-adrenoceptor agonists such as arformoterol, carmoterol, indacaterol, GSK-159797, GSK-597901, 159802, 642444 and 678007 are under development for the treatment of asthma and chronic obstructive pulmonary disease. The majority of these compounds are (R,R)-isomers in order to control desensitisation and accumulation. Several options for combination products are currently being evaluated in parallel with the development of these ultra LABAs. Once-daily dosing of an ultra LABA would be a significant convenience and probably a compliance-enhancing advantage leading to improved overall clinical outcomes in patients with asthma and chronic obstructive pulmonary disease. The only limits set for the development of a LABA with a new product profile are medical needs and marketing opportunities.
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Affiliation(s)
- Mario Cazzola
- Department of Respiratory Medicine, A. Cardarelli Hospital, Via del Parco Margherita 24, 80121 Naples, Italy.
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Boulton DW, Fawcett JP. Beta2-agonist eutomers: a rational option for the treatment of asthma? ACTA ACUST UNITED AC 2005; 1:305-11. [PMID: 14720033 DOI: 10.1007/bf03256624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Beta2-adrenoceptor agonists (beta2-agonists) such as albuterol (salbutamol) and terbutaline and their long-acting analogs salmeterol and formoterol are widely used as bronchodilators in the treatment of asthma. They are chiral drugs historically marketed as racemic mixtures of an active (eutomer) and essentially inactive (distomer) stereoisomer. Despite their obvious therapeutic value and widespread use, beta2-agonists have been implicated, somewhat controversially, in causing an increase in asthma mortality and a deterioration of asthma control by a mechanism that remains elusive. Inherent toxicity of the distomers has been widely touted as an explanation and has given rise to pressure for the replacement of the racemates with pure eutomer formulations (the so-called chiral or racemic switch). This has culminated in the recent introduction into clinical practice of the single active stereoisomer of albuterol (levalbuterol) and the promise of other pure beta2-agonist eutomer formulations to follow. This article examines the evidence on which these chiral switches are based. Clinical studies designed to reveal negative effects of beta2-agonists have searched for reductions in lung function, increases in airway responsiveness to bronchoconstrictor mediators and worsening of asthma control. Crossover studies administering the pure stereoisomers and racemate of albuterol have not shown a clear superiority of the pure eutomer formulation over the racemate in terms of either bronchial hyperresponsiveness, tachyphylaxis to bronchoprotective effects or improvements in lung function. Clinical toxicity of beta2-agonist distomers on any aspect of asthmatic lung function has also not been demonstrated in the relatively short-term inhalational studies (single dose or repeated dose studies <1 week) that have been carried out. In animal studies, the administration of beta2-agonist racemates and distomers has been shown to enhance bronchial hyperresponsiveness but only in ovalbumin-sensitized animals where the relevance to humans is questionable. The pharmacokinetics and metabolism of beta(2)-agonist stereoisomers appear to be essentially similar whether administered as single stereoisomers or as racemates. Levalbuterol may be slightly more potent than an equivalent dose given as racemate, but there is some evidence that it forms a small amount of the distomer in vivo which detracts somewhat from its purported benefits over use of the racemate. Whilst there remains a clear need for studies of longer duration with sensitive clinical endpoints to evaluate the benefits of beta2-agonist eutomers and to investigate distomer toxicity, the chiral switch for beta2-agonists in general, and for albuterol in particular, does not appear to be justified on the basis of the evidence available to date.
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Affiliation(s)
- David W Boulton
- Clinical Discovery, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543-4000, USA.
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Zhang M, Fawcett JP, Shaw JP. Stereoselective urinary excretion of formoterol and its glucuronide conjugate in human. Br J Clin Pharmacol 2002; 54:246-50. [PMID: 12236843 PMCID: PMC1874421 DOI: 10.1046/j.1365-2125.2002.01641.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AIMS Formoterol is an inhaled beta2-adrenoceptor agonist used as a racemic mixture of the active (R; R)- and inactive (S; S)-enantiomers (rac-formoterol). Glucuronidation is an important route of metabolism in humans which occurs faster for (S; S)-formoterol in human liver microsomes. The aim of this study was to investigate the stereoselectivity of urinary excretion of formoterol and its glucuronide conjugate after oral dosing with rac-formoterol. METHODS Seven nonsmoking volunteers (six males, one female) were included in the study. After an overnight fast, a single 60 micro g oral dose of rac-formoterol fumarate dihydrate was ingested. Urine samples were collected at 1 h intervals for the first 4 h, and at 6, 8, 12 and 24 h after dosing. Formoterol enantiomers were analysed by chiral h.p.l.c. assay and formoterol glucuronides were determined as formoterol enantiomers after enzymatic cleavage with beta-glucuronidase. RESULTS The female subject displayed a different pattern of metabolism and statistical analysis was therefore limited to data for the six males. The median (range) of the total urinary excretion of formoterol was 37.8% (20.9-51.2%) of the dose. The medians (ranges) of the amounts of (R; R)- and (S; S)-formoterol and of (R; R)- and (S; S)-formoterol glucuronide excreted were 2.1 (1.0-2.9), 3.5 (2.6-3.8), 21.0 (13.1-31.0) and 10.3 (4.2-14.6)%, respectively, of the dose. Unchanged (S; S)-formoterol excretion was significantly greater than that of unchanged (R; R)-formoterol and (R; R)-formoterol glucuronide excretion was significantly greater than that of (S; S)-formoterol glucuronide. The total RR-formoterol (unchanged drug plus glucuronide) excreted was significantly greater than the total (S; S)-formoterol. CONCLUSIONS Our study demonstrates that the urinary excretion of formoterol in male humans after oral administration of rac-formoterol is stereoselective with preferential excretion of the active (R; R)-formoterol as unchanged drug and glucuronide. The different pattern of metabolism in the female subject provides impetus for further studies of the effect of gender on the stereoselective metabolism and pharmacokinetics of formoterol.
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Affiliation(s)
- Mei Zhang
- Department of Clinical Pharmacology, Christchurch School of Medicine, School of Pharmacy, University of Otago, PO Box 913, Dunedin, New Zealand
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Handley DA, Senanayake CH, Dutczak W, Benovic JL, Walle T, Penn RB, Wilkinson HS, Tanoury GJ, Andersson RGG, Johansson F, Morley J. Biological actions of formoterol isomers. Pulm Pharmacol Ther 2002; 15:135-45. [PMID: 12090787 DOI: 10.1006/pupt.2001.0327] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Racemic beta(2) agonists, composed of equal amounts of (R)- and (S)-isomers, can display anomalous actions that compromise their effectiveness as asthma therapies. Loss of efficacy during regular use is characteristic of isoprenaline, albuterol and terbutaline and has in part been attributed to the biological effects of the (S)-isomer. This hypothesis was applied to the (R,R)- and (S,S)-isomers of formoterol. (R,R)-formoterol had 1000-times greater affinity (2.9 nm) to the human beta(2) adrenoceptor than (S,S)-formoterol (3100 nm), with receptor binding modulating intracellular cAMP levels. The minimum lethal intravenous (IV) dose was determined to be 100 mg/kg for (R,R)- and 50 mg/kg for (S,S)-formoterol, suggesting that the toxicity of (S,S)-formoterol may not be related to the binding of beta(2) adrenoceptors. In tissues pretreated with (S,S)-formoterol but not with (R,R)- or racemic formoterol contractions to high concentrations of carbachol were exaggerated. In vivo experiments with sensitized guinea pigs demonstrated that (R,R)-formoterol inhibited both histamine and antigen-induced bronchoconstriction with greater potency than (R,R/S,S)-formoterol while (S,S)-formoterol was ineffective. Metabolic radiolabeling experiments of (R,R)-, (S,S)- or (R,R/S,S)-formoterol with crude human liver phenolsulfotransferase (PST) determined the V(max)/K(m) values to be (0.151), (0.74) and (0.143), respectively. The reciprocal plot illustrates a 2-fold reduction in sulfation rate when (R,R)-formoterol is present as a single isomer. The data presented here suggest that (R,R)-formoterol binds to the beta(2) adrenoceptor and inhibits the contraction of bronchial tissues by spasmogens. However, (S,S)-formoterol exhibits properties inconsistent as an asthma therapeutic and may antagonize the actions of (R,R)-formoterol.
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Affiliation(s)
- Dean A Handley
- Sepracor Inc., 111 Locke Drive, Marlborough, MA 01752, USA.
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15
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Vakily M, Mehvar R, Brocks D. Stereoselective pharmacokinetics and pharmacodynamics of anti-asthma agents. Ann Pharmacother 2002; 36:693-701. [PMID: 11918522 DOI: 10.1345/aph.1a248] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To review the previously published studies on pharmacokinetics and pharmacodynamics of chiral drugs used in the treatment of asthma. DATA SOURCES Primary and review articles were identified with a MEDLINE search (1980-May 2001) and through secondary sources. STUDY SELECTION AND DATA EXTRACTION All English-language studies and reviews obtained from the MEDLINE search pertaining to stereoselective pharmacokinetics and pharmacodynamics of chiral anti-asthma drugs were assessed. DATA SYNTHESIS Several anti-asthma drugs (e.g., beta(2)-adrenergic agonists, leukotriene modifiers) are chiral and marketed as racemates, which consist of equal proportions of 2 enantiomers. Significant stereoselectivity has also been reported in pharmacodynamics and pharmacokinetics of the beta(2)-agonists. The enantiomers of beta(2)-agonists in the R configuration are primarily responsible for the bronchodilating effects of the racemate. The plasma concentrations of the enantiomers of anti-asthma drugs may differ as a reflection of stereoselectivity in clearance, volume of distribution, and route of administration. CONCLUSIONS Stereoselectivity in the pharmacokinetics of anti-asthma drugs may complicate the relationship between dose and/or plasma concentration of racemic drug versus effect relationship. An appreciation of the stereoselective pharmacokinetics and pharmacodynamics of chiral anti-asthma drugs may optimize the use of these agents in asthmatic patients.
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Affiliation(s)
- Majid Vakily
- Department of Drug Metabolism and Pharmacology, TAP Pharmaceutical Product Inc., Lake Forest, IL 60045-4832, USA.
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16
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Guijt RM, Baltussen E, van Dedem GWK. Use of bioaffinity interactions in electrokinetically controlled assays on microfabricated devices. Electrophoresis 2002; 23:823-35. [PMID: 11920867 DOI: 10.1002/1522-2683(200203)23:6<823::aid-elps823>3.0.co;2-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this contribution, the role of bioaffinity interactions on electrokinetically controlled microfabricated devices is reviewed. Interesting applications reported in the literature include enzymatic assays, where enzyme and enzyme inhibition kinetics were studied, often in combination with electrophoretic separation. Attention is paid towards developments that could lead to implementation of electrokinetically controlled microdevices in high-throughput screening. Furthermore, enzyme-facilitated detection in combination with electrophoretic separation on microdevices is discussed. Various types of immunoassays have been implemented on the microchip format. The selectivity of antibody-antigen interaction has been exploited for the detection of analytes in complex sample matrices as required, for example, in clinical chemistry. Binding kinetics as well as stoichiometry were studied in chip-based assays. Automated mixing protocols as well as the demonstration of a parallel immunoassay allow implementation of microdevices in high-throughput screening. Furthermore, demonstration of immunoassays on cheap polymeric microdevices opens the way towards the fabrication of disposable devices, a requirement for commercialization and therefore for application in routine analyses.
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Affiliation(s)
- Rosanne M Guijt
- Kluyver Laboratory for Biotechnology, Department of Analytical Biotechnology, Delft University of Technology, Julianalaan 67, NL-2628 BC Delft, The Netherlands.
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17
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Abstract
Each month, subscribers to The Formulary® Monograph Service receive five to six researched monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board called The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical pharmacy are discussed on The F.I.X. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The July 2001 Formulary monographs are on ima-tinib mesylate, alemtuzumab, parecoxib sodium, pramlintide acetate, and busesonide modified-release capsules. The DUE is on galantamine.
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Affiliation(s)
- Dennis J. Cada
- Drug Information Center and College of Pharmacy, Washington State University at Spokane, 601 West First Avenue, Spokane, WA 99201-3899
| | - Terri Levien
- Drug Information Center and College of Pharmacy, Washington State University at Spokane, 601 West First Avenue, Spokane, WA 99201-3899
| | - Danial E. Baker
- Drug Information Center and College of Pharmacy, Washington State University at Spokane, 601 West First Avenue, Spokane, WA 99201-3899
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18
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Abstract
A new generation of bronchodilators is being developed for acute asthma management-single-isomer beta-agonists. These drugs consist only of the active bronchodilatory isomer (eutomer); they do not have the inactive and potentially harmful isomer (distomer) that is present in marketed racemic beta-agonists. Clinical studies comparing the effectiveness of (R)-albuterol (levalbuterol) with racemic albuterol established a strong rationale for using single-isomer beta-agonists in place of the racemic mixture: reduced dosages provide equivalent bronchodilatory effects with fewer beta-mediated side effects. Higher dosages achieve superior bronchodilation in episodes of severe asthma and may reduce costs of emergency department treatment.
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Affiliation(s)
- D A Handley
- Sepracor, Inc., Marlborough, Massachusetts 01752, USA
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19
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Jonsson AP, Griffiths WJ, Bratt P, Johansson I, Strömberg N, Jörnvall H, Bergman T. A novel Ser O-glucuronidation in acidic proline-rich proteins identified by tandem mass spectrometry. FEBS Lett 2000; 475:131-4. [PMID: 10858503 DOI: 10.1016/s0014-5793(00)01645-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Human acidic proline-rich salivary protein PRP-1 and its C-terminally truncated form PRP-3 were analyzed by electrospray tandem mass spectrometry. Post-translational modifications were detected and characterized. A pyroglutamic acid residue was demonstrated at the N-terminus, Ser-8 and Ser-22 were shown to be phosphorylated and an O-linked glucuronic acid conjugation was identified. The latter modification was located to Ser-17 and found to be present in approximately 40% of the polypeptides.
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Affiliation(s)
- A P Jonsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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