Ciclesonide uptake and metabolism in human alveolar type II epithelial cells (A549)
© Nonaka et al; licensee BioMed Central Ltd. 2007
Received: 19 April 2007
Accepted: 27 September 2007
Published: 27 September 2007
Ciclesonide is a novel inhaled corticosteroid for the treatment of airway inflammation. In this study we investigated uptake and in vitro metabolism of ciclesonide in human alveolar type II epithelial cells (A549). Ciclesonide uptake was compared with fluticasone propionate, an inhaled corticosteroid that is not metabolized in lung tissue. A549 cells were incubated with 2 × 10-8 M ciclesonide or fluticasone propionate for 3 to 30 min to determine uptake; or with 2 × 10-8 M ciclesonide for 1 h, followed by incubation with drug-free buffer for 3, 6, and 24 h to analyze in vitro metabolism. High performance liquid chromatography with tandem mass spectrometry was used to measure the concentrations of both corticosteroids and metabolites.
At all time points the mean intracellular concentration was higher for ciclesonide when compared with fluticasone propionate. Activation of ciclesonide to desisobutyryl-ciclesonide (des-CIC) was confirmed and conjugates of des-CIC with fatty acids were detected. The intracellular concentration of ciclesonide decreased over time, whereas the concentration of des-CIC remained relatively stable: 2.27 to 3.19 pmol/dish between 3 and 24 h. The concentration of des-CIC fatty acid conjugates increased over time, with des-CIC-oleate being the main metabolite.
Uptake of ciclesonide into A549 cells was more efficient than that of the less lipophilic fluticasone propionate. Intracellular concentrations of the pharmacologically active metabolite des-CIC were maintained for up to 24 h. The local anti-inflammatory activity of ciclesonide in the lung may be prolonged by the slow release of active drug from the depot of fatty acid esters.
Modern inhaled corticosteroids are currently the most effective drugs used in long-term asthma therapy, combining potent anti-inflammatory activity with fast metabolic inactivation [1, 2]. Inhaled corticosteroids can reduce bronchial hyperresponsiveness, asthma symptoms, frequency of asthma exacerbations, and improve lung function and quality of life . On the other hand, long-term treatment with inhaled corticosteroids can be associated with systemic adverse effects, such as cortisol suppression, formation of cataracts, decreased bone density, and growth suppression in children .
The efficacy of an inhaled corticosteroid and its potential to cause systemic adverse effects are based on its pharmacodynamic and pharmacokinetic properties [3–5]. These properties are determined by the reversible binding of the drug to the glucocorticoid receptor, which is present in almost all cell types . Thus, local therapeutic benefits as well as unwanted adverse effects are mediated by the same receptor .
Ciclesonide is a new generation inhaled corticosteroid for the treatment of asthma and allergic rhinitis [7–9]. In contrast to other inhaled corticosteroids that bind directly to the glucocorticoid receptor, e.g. fluticasone propionate, ciclesonide is a prodrug with almost no receptor binding affinity. Airway esterases convert ciclesonide to its pharmacologically active metabolite desisobutyryl-ciclesonide (des-CIC), which has a 100-fold higher binding affinity for the glucocorticoid receptor than its parent compound [7, 10]. The receptor binding affinity varies among inhaled corticosteroids and is expressed as the binding affinity relative to dexamethasone with an affinity of 100 . Des-CIC and fluticasone propionate are among the most potent corticosteroids with binding affinities relative to dexamethasone of 1200 and 1800, respectively .
The objective of this study was to investigate the uptake of ciclesonide in human alveolar typeII epithelial cells, using the human-lung derived carcinoma A549 cell line as an established in vitro model for studying drug metabolism and delivery in the lung epithelium . Ciclesonide uptake was compared with the uptake of fluticasone propionate, a potent and widely used inhaled corticosteroid . In addition, the in vitro metabolism of ciclesonide in A549 cells was examined, to evaluate the formation of the pharmacologically active metabolite des-CIC and its conjugation with fatty acids in human lung epithelial cells.
Uptake of ciclesonide and fluticasone propionate in A549 cells
Intracellular concentrations of ciclesonide, des-CIC, and des-CIC-oleate during incubation with 2 × 10-8 M ciclesonide
Incubation time (min)
Mean concentration ± SD (pmol/dish)a)
15.04 ± 2.48
0.41 ± 0.05
0.00 ± 0.00
17.86 ± 2.30
0.33 ± 0.19
0.00 ± 0.00
36.63 ± 23.48
0.67 ± 0.13
0.02 ± 0.05
34.22 ± 9.15
0.97 ± 0.14
0.12 ± 0.07
48.21 ± 5.19
1.72 ± 0.14
0.40 ± 0.06
In vitro metabolism of ciclesonide in A549 cells
In asthma therapy, alveolar epithelial cells are one of the most important targets for inhaled corticosteroids, because these cells are involved in the secretion of many pro-inflammatory proteins [21, 22]. Thus, the efficient uptake of an inhaled corticosteroid into these cells is a prerequisite for the exertion of its anti-inflammatory activity. The human epithelial lung adenocarcinoma cell line A549 provides a useful model for drug transport and metabolic processes in epithelial type II cells . In this study we evaluated the uptake efficiency of the two corticosteroids ciclesonide and fluticasone propionate into A549 cells and investigated the metabolism of ciclesonide in this cell type.
After incubation, significantly higher concentrations of ciclesonide than fluticasone propionate were detected in A549 cells, suggesting a more efficient uptake of ciclesonide into the cells (p < 0.001). These observations might be correlated with the lipophilicity of the compounds. High lipophilicity facilitates the passage of the drug through the phospholipid bilayer of the cell. The logD (logarithm of the effective partition coefficient for dissociative systems in octanol-water) values at pH 7.4 are 5.0 for ciclesonide and 4.1 for fluticasone propionate, indicating that ciclesonide has a 7.9-fold higher lipophilicity compared with fluticasone propionate.
Binding of drugs to plasma proteins is another factor that may affect the uptake of drugs into cells. In the systemic circulation, 99% of ciclesonide and 90% of fluticasone propionate are protein-bound , leading to the assumption that in vivo more unbound fluticasone propionate is available for uptake compared with ciclesonide. However, the protein content of the incubation media in these experiments was 0.1% BSA, which is lower than the protein content in the systemic circulation. Furthermore, the exact protein concentration in vivo on the surface of alveolar cells is not known. Therefore, it is not certain whether the difference in protein binding between the two corticosteroids might have an influence on the results of this study.
After the uptake into the A549 cells, ciclesonide is converted by airway esterases to its pharmacologically active metabolite des-CIC, which is then conjugated with fatty acids. During the 24-h drug-free incubation period, the intracellular levels of des-CIC remained stable, while ciclesonide concentrations decreased to trace amounts at 24 h and levels of des-CIC fatty acid conjugates increased over time. Des-CIC-oleate was the major fatty acid conjugate, and after 24 h of drug-free incubation, the major compound detected. Similar results were reported previously in vitro for precision-cut human lung slices and for human lung tissue after in vivo inhalation of ciclesonide [18, 23]. The total amount of intracellular ciclesonide (sum of ciclesonide, des-CIC, and des-CIC-oleate) remained stable over the 24 h of drug-free incubation. In a previous study using similar experimental conditions, the anti-inflammatory potency of des-CIC in A549 cells was demonstrated by the inhibition of cytokine production .
Overall, this study demonstrated that ciclesonide is effectively taken up into human alveolar type II epithelial (A549) cells and metabolized to its pharmacologically active metabolite des-CIC and fatty acid conjugates of des-CIC. Levels of des-CIC remained constant over a 24 h period, possibly because des-CIC may be formed from either ciclesonide or des-CIC-oleate. Fatty acid esters are much more lipophilic compared with the parent compound ciclesonide . These inactive esters remain in the cells, where they reconvert to the active metabolite, thus prolonging the exposure time and local anti-inflammatory activity of ciclesonide in the lung. The slow-release pool of active drug may contribute to the proven efficacy of once-daily inhaled ciclesonide in asthma therapy, as was shown in several clinical studies [25–30].
Cells and materials
Human alveolar type II epithelial cells (A549) were obtained from Dainippon Pharmaceutical Co., Ltd. (Osaka. Japan). Ciclesonide, des-CIC, des-CIC-oleate, des-CIC-palmitate, deuterium-labeled des-CIC, and fluticasone propionate were supplied by ALTANA Pharma AG (Konstanz, Germany). Dulbecco's Modified Eagle Medium (DMEM), Dulbecco's phosphate-buffered saline (PBS), fetal bovine serum (FBS), and antibiotics were purchased from Invitrogen/GIBCO (Tokyo, Japan). Bovine serum albumin (BSA), ammonium acetate, and HPLC-grade ethanol (99.5%) were from Wako Pure Chemicals Industries, Ltd. (Osaka, Japan). Ethylenediamine-N, N, N', N'-tetraacetic acid tetrasodium salt (EDTA-4Na) was supplied by Dojin Laboratories, Inc. (Kumamoto, Japan). Acetonitrile was from Fisher Scientific Japan, Co. Ltd. (Tokyo, Japan), and trypsin/EDTA and trypsin neutralizing solution from Sanko Junyaku Co., Ltd. (Tokyo, Japan).
Cell culture conditions
A549 cells were grown in DMEM supplemented with 10% (v/v) FBS at 37°C and saturated humidity (5% CO2, 95% air) in a CO2 incubator (Wakenyaku Co., Ltd., Kyoto, Japan) using 10 cm culture dishes. When confluence was reached, medium was replaced by DMEM/0.1% (w/v) BSA and cells were cultured for 24 h.
Uptake of corticosteroids
After initial cultivation, A549 cells were washed twice with 10 ml/dish sterile PBS. Stock solutions of ciclesonide and fluticasone propionate were prepared using HPLC-grade ethanol and diluted 1000-fold with assay medium to generate the initial substrate concentration. The cells were incubated in DMEM/0.1%(w/v) BSA (5 ml/dish) with 2 × 10-8 M ciclesonide or fluticasone propionate for 3, 5, 10, 20, or 30 min. At the end of the incubation period, the medium was removed by aspiration, dishes were washed five times with ice-chilled PBS (10 ml/dish) and incubated with 5 mM EDTA-4Na/PBS for further 5 minutes in the CO2 incubator. The cells were detached from the dishes and harvested. Each dish was washed five times with ice-chilled PBS. The cell pellets obtained by centrifugation (Kubota 8700: 1500 rpm, 5 min, 4°C) were frozen in liquid nitrogen and kept at -80°C until further use.
Metabolism of ciclesonide
After initial cultivation, A549 cells were washed five times with 10 ml/dish sterile PBS. An ethanolic stock solution of ciclesonide was diluted 1000-fold with assay medium to generate the initial ciclesonide concentration The cells were incubated for 1 h in DMEM/0.1% (w/v) BSA (5 ml/dish) containing 2 × 10-8 M ciclesonide as described above in a CO2 incubator. At the end of the incubation period, dishes were washed five times with PBS and incubated for 3, 6, or 24 h at the same conditions in 5 ml/dish fresh medium (DMEM/0.1% (w/v) BSA). At each indicated time point, the medium was removed by aspiration, 5 mM EDTA-4Na/PBS added and dishes were incubated for further 5 min. The cells were detached from the dishes and harvested. Each dish was washed five times with ice-chilled PBS. The cell pellets obtained by centrifugation were frozen in liquid nitrogen and kept at -80°C until further use.
Preparation of cell extracts
Cell pellets were homogenized in 0.8 ml ethanol using an ultrasonic homogenizer (Sonifier 250, Branson Ultrasonics Corporation, Danbury, Conn, USA). After centrifugation for 15 min at 4°C, aliquots of the supernatant were stored at -20°C until further use.
Liquid chromatography and tandem mass spectrometry (LC/MS/MS)
Ciclesonide, des-CIC, des-CIC fatty acid conjugates, and fluticasone propionate were separated by high performance liquid chromatography (HPLC; Agilent HP1100, Agilent Technologies, Tokyo, Japan) using a 5μm Hypersil® Phenyl 2 column (50 × 4.6 mm; Thermo Electron, K.K., Yokohama, Japan) The mobile phase consisted of 25% (v/v) acetonitrile/purified water/1 mM ammonium acetate and 95% (v/v) acetonitrile/purified water/1 mM ammonium acetate at a flow rate of 1.0 ml/min for a total run time of 7 min. As an internal standard, an analogue of des-CIC carrying a deuterium label at the cyclohexyl group was used. The analytes were detected by a tandem mass spectrometry system (API3000, Applied Biosystems, Tokyo, Japan) with a turbo ion spray source and negative multiple reaction monitoring scan mode.
The concentrations of ciclesonide, fluticasone propionate, and metabolites in the assay samples were determined by comparing calibration curves using the Analyst 1.1 data processing program. The calibration curves were drawn from the primary regression line determined by the least-squares method (weighting factor: 1/x). The lower limits of quantification (LLOQ), determined from the calibration curves, were defined as 0.10 ng/ml for ciclesonide and des-CIC-oleate, 0.20 ng/ml for des-CIC and des-CIC-palmitate, and 0.40 ng/ml for fluticasone propionate.
Differences in concentrations between samples treated with either ciclesonide or fluticasone dipropionate were determined by using the Aspin Welch t-test. The concentrations are given as mean ± standard deviation.
The authors thank Dr. Tanja Henrichs and Dr. Kathy B. Thomas (Nycomed GmbH, Department Medical Writing, Konstanz, Germany) for helpful suggestions during the preparation of this article. The study presented in this article was sponsored by Teijin Pharma Limited, Tokyo, Japan, and performed in cooperation with Nycomed GmbH (formerly ALTANA Pharma AG), Konstanz, Germany.
- Georgitis JW: The 1997 Asthma Management Guidelines and therapeutic issues relating to the treatment of asthma. National Heart, Lung, and Blood Institute. Chest. 1999, 115: 210-217.View ArticlePubMedGoogle Scholar
- Williams SG, Schmidt DK, Redd SC, Storms W: Key clinical activities for quality asthma care. Recommendations of the National Asthma Education and Prevention Program. MMWR Recomm Rep. 2003, 52: 1-8.PubMedGoogle Scholar
- Barnes PJ, Pedersen S, Busse WW: Efficacy and safety of inhaled corticosteroids. New developments. Am J Respir Crit Care Med. 1998, 157: S1-53.View ArticlePubMedGoogle Scholar
- Derendorf H: Pharmacokinetic and pharmacodynamic properties of inhaled corticosteroids in relation to efficacy and safety. Respir Med. 1997, 91 Suppl A: 22-28.View ArticlePubMedGoogle Scholar
- Rohatagi S, Appajosyula S, Derendorf H, Szefler S, Nave R, Zech K, Banerji D: Risk-benefit value of inhaled glucocorticoids: a pharmacokinetic/pharmacodynamic perspective. J Clin Pharmacol. 2004, 44: 37-47.View ArticlePubMedGoogle Scholar
- Hochhaus G, Mollmann H, Derendorf H, Gonzalez-Rothi RJ: Pharmacokinetic/pharmacodynamic aspects of aerosol therapy using glucocorticoids as a model. J Clin Pharmacol. 1997, 37: 881-892.View ArticlePubMedGoogle Scholar
- Dietzel K, Engelstatter R, Keller A: Ciclesonide: an on-site-activated steroid New drugs for asthma, allergy and COPD. Edited by: Hansel TT and Barnes PJ. 2001, Basel, Karger, 91-93.View ArticleGoogle Scholar
- Mealy NE, Bayes M, Castaner J: Ciclesonide. Drugs of the future. 2001, 26: 1033-1039.View ArticleGoogle Scholar
- Nave R, Wingertzahn MA, Brookman S, Kaida S, Matsunaga T: Safety, tolerability, and exposure of ciclesonide nasal spray in healthy and asymptomatic subjects with seasonal allergic rhinitis. J Clin Pharmacol. 2006, 46: 461-467.View ArticlePubMedGoogle Scholar
- Dent G: Ciclesonide (Byk Gulden). Current Opinion in Investigational Drugs. 2002, 3: 78-83.PubMedGoogle Scholar
- Derendorf H, Nave R, Drollmann A, Cerasoli F, Wurst W: Relevance of pharmacokinetics and pharmacodynamics of inhaled corticosteroids to asthma. Eur Respir J. 2006, 28: 1042-1050.View ArticlePubMedGoogle Scholar
- Pedersen S, O'Byrne P: A comparison of the efficacy and safety of inhaled corticosteroids in asthma. Allergy. 1997, 52: 1-34.View ArticlePubMedGoogle Scholar
- Lipworth BJ, Jackson CM: Safety of inhaled and intranasal corticosteroids: lessons for the new millennium. Drug Saf. 2000, 23: 11-33.View ArticlePubMedGoogle Scholar
- Edsbacker S, Brattsand R: Budesonide fatty-acid esterification: a novel mechanism prolonging binding to airway tissue. Review of available data. Ann Allergy Asthma Immunol. 2002, 88: 609-616.View ArticlePubMedGoogle Scholar
- Tunek A, Sjodin K, Hallstrom G: Reversible formation of fatty acid esters of budesonide, an antiasthma glucocorticoid, in human lung and liver microsomes. Drug Metab Dispos. 1997, 25: 1311-1317.PubMedGoogle Scholar
- Nave R, Hummel RP, Wohlsen A, Herzog R, Zech K: The active metabolite of ciclesonide, des-isobutyryl ciclesonide, forms highly lipophilic fatty acid conjugates in precision-cut rat lung slices. American Journal of Respiratory and Critical Care Medicine. 2004, ATS 2004, 169: A91-Google Scholar
- Nave R, Meyer W, Fuhst R, Zech K: Formation of fatty acid conjugates of ciclesonide active metabolite in the rat lung after 4-week inhalation of ciclesonide. Pulm Pharmacol Ther. 2005, 18: 390-396.View ArticlePubMedGoogle Scholar
- Nave R, Fisher R, Zech K: In Vitro metabolism of ciclesonide in human lung and liver precision-cut tissue slices. Biopharm Drug Dispos. 2006, 27: 197-207.View ArticlePubMedGoogle Scholar
- Foster KA, Oster CG, Mayer MM, Avery ML, Audus KL: Characterization of the A549 cell line as a type II pulmonary epithelial cell model for drug metabolism. Exp Cell Res. 1998, 243: 359-366.View ArticlePubMedGoogle Scholar
- Kelly HW: Pharmaceutical characteristics that influence the clinical efficacy of inhaled corticosteroids. Ann Allergy Asthma Immunol. 2003, 91: 326-334.View ArticlePubMedGoogle Scholar
- Barnes PJ: Pathophysiology of asthma. Br J Clin Pharmacol. 1996, 42: 3-10.PubMed CentralView ArticlePubMedGoogle Scholar
- Schweibert LM, Stellato C, Schleimer RP: The epithelium as a target of glucocorticoid action in the treatment of asthma. Am J Respir Crit Care Med. 1996, 154: S16-S19.View ArticleGoogle Scholar
- Drollmann A, Watz H, Nave R, Boss H, Magnussen H, Hoffmann H: In vivo metabolism of ciclesonide in the human lung. Proc Am Thorac Soc. 2006, ATS 2006, San Diego, USA, 3: A75-Google Scholar
- Nonaka T, Sugiyama H, Kishimoto T, Horiuchi H, Taneda M, Sakuma Y, Hoshina K, Kamimura T: Effect of a novel inhaled glucocorticoid, ciclesonide, on an allergen-induced asthmatic response in rats and its prolonged anti-inflammatory activity in vitro. European Respiratory Journal. 2002, 20: P652-Google Scholar
- Postma DS, Sevette C, Martinat Y, Schloesser N, Aumann J, Kafé H: Treatment of asthma by the inhaled corticosteroid ciclesonide given either in the morning or evening. Eur Respir J. 2001, 17: 1083-1088.View ArticlePubMedGoogle Scholar
- Chapman KR, Patel P, D'Urzo AD, Alexander M, Mehra S, Oedekoven C, Engelstatter R, Boulet LP: Maintenance of asthma control by once-daily inhaled ciclesonide in adults with persistent asthma. Allergy. 2005, 60: 330-337.View ArticlePubMedGoogle Scholar
- Langdon CG, Adler M, Mehra S, Alexander M, Drollmann A: Once-daily ciclesonide 80 or 320mug for 12 weeks is safe and effective in patients with persistent asthma. Respir Med. 2005, 99: 1275-1285.View ArticlePubMedGoogle Scholar
- Niphadkar P, Jagannath K, Joshi JM, Awad N, Boss H, Hellbardt S, Gadgil DA: Comparison of the efficacy of ciclesonide 160 microg QD and budesonide 200 microg BID in adults with persistent asthma: a phase III, randomized, double-dummy, open-label study. Clin Ther. 2005, 27: 1752-1763.View ArticlePubMedGoogle Scholar
- Boulet LP, Drollmann A, Magyar P, Timar M, Knight A, Engelstatter R, Fabbri L: Comparative efficacy of once-daily ciclesonide and budesonide in the treatment of persistent asthma. Respir Med. 2006, 100: 785-794.View ArticlePubMedGoogle Scholar
- Buhl R, Vinkler I, Magyar P, Gyori Z, Rybacki C, Middle MV, Escher A, Engelstatter R: Comparable efficacy of ciclesonide once daily versus fluticasone propionate twice daily in asthma. Pulm Pharmacol Ther. 2006, 19: 404-412.View ArticlePubMedGoogle Scholar
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