In vitro metabolism of beclomethasone dipropionate, budesonide, ciclesonide, and fluticasone propionate in human lung precision-cut tissue slices

Characterisation of ciclesonide metabolism in human placentae across gestation

INTRODUCTION

Current clinical management of pregnancies at risk of preterm delivery includes maternal antenatal corticosteroid (ACS) treatment. ACS activate the glucocorticoid receptor (GR) in all fetal tissues, maturing the lungs at the cost of impaired brain development, creating a need for novel treatments. The prodrug ciclesonide (CIC) activates the GR only when converted to des-CIC by specific enzymes, including acetylcholinesterase (ACHE) and carboxylesterase 1 and 2 (CES1, CES2). Importantly, the human placenta expresses ACHE and CES, and could potentially produce des-CIC, resulting in systemic fetal exposure and GR activation in all fetal tissues. We therefore investigated CES gene expression and conversion of CIC to des-CIC in human placentae collected during the second trimester (Tri2), and at preterm and term birth.

METHODS

Differential expression analysis was performed in Tri2 (n = 27), preterm (n = 34), and term (n = 40) placentae using the DESeq2 R-package. Conversion of CIC to des-CIC was measured in a subset of placenta samples (Tri2 n = 7, preterm n = 26, term n = 20) using functional assays.

RESULTS

ACHE mRNA expression was higher in Tri2 male than preterm and term male placentae only, whereas CES1 mRNA expression was higher in Tri2 than preterm or term placentae of both sexes. Conversion of CIC to des-CIC did not differ between gestational ages.

DISCUSSION

Conversion of CIC to des-CIC by the human placenta may preclude its use as a novel GR-agonist in threatened preterm birth. In vivo studies are required to confirm the extent to which placental activation occurs after maternal treatment.

Insights into Inhalation Drug Disposition: The Roles of Pulmonary Drug-Metabolizing Enzymes and Transporters

The past five decades have witnessed remarkable advancements in the field of inhaled medicines targeting the lungs for respiratory disease treatment. As a non-invasive drug delivery route, inhalation therapy offers numerous benefits to respiratory patients, including rapid and targeted exposure at specific sites, quick onset of action, bypassing first-pass metabolism, and beyond. Understanding the characteristics of pulmonary drug transporters and metabolizing enzymes is crucial for comprehending efficient drug exposure and clearance processes within the lungs. These processes are intricately linked to both local and systemic pharmacokinetics and pharmacodynamics of drugs. This review aims to provide a comprehensive overview of the literature on lung transporters and metabolizing enzymes while exploring their roles in exogenous and endogenous substance disposition. Additionally, we identify and discuss the principal challenges in this area of research, providing a foundation for future investigations aimed at optimizing inhaled drug administration. Moving forward, it is imperative that future research endeavors to focus on refining and validating in vitro and ex vivo models to more accurately mimic the human respiratory system. Such advancements will enhance our understanding of drug processing in different pathological states and facilitate the discovery of novel approaches for investigating lung-specific drug transporters and metabolizing enzymes. This deeper insight will be crucial in developing more effective and targeted therapies for respiratory diseases, ultimately leading to improved patient outcomes.

Budesonide associated with exogenous pulmonary surfactant in a novel formulation to improve the delivery to the lung

Lung delivery for glucocorticoids (GCs) is very low and depends on the system used. Exogenous pulmonary surfactant (EPS) is a promising tool to transporting GCs efficiently to the airways. We developed a new formulation of EPS with Budesonide (BUD) incorporated into EPS membranes (EPS-BUD) to improve lung delivery of BUD. We evaluated the biodistribution and pharmacokinetic of the transported BUD by intra-tracheal instillation of EPS-BUD in healthy rats. Aqueous suspension of Budesonide was used as control. Budesonide and its esters present in trachea, kidneys and lungs were determined by HPLC. The delivery of BUD in lung for EPS-BUD group was 75 % of total instilled and only 35 % for the control group. BUD was rapidly internalized in pneumocytes and a high proportion of Budesonide esters and persistent concentrations of active free BUD were found for up to 6 h after instillation. The new EPS-BUD formulation developed significantly improves the deposition and increases the permanence of BUD in lung.

In vitro and ex vivo models in inhalation biopharmaceutical research - advances, challenges and future perspectives

Oral inhalation results in pulmonary drug targeting and thereby reduces systemic side effects, making it the preferred means of drug delivery for the treatment of respiratory disorders such as asthma, chronic obstructive pulmonary disease or cystic fibrosis. In addition, the high alveolar surface area, relatively low enzymatic activity and rich blood supply of the distal airspaces offer a promising pathway to the systemic circulation. This is particularly advantageous when a rapid onset of pharmacological action is desired or when the drug is suffering from stability issues or poor biopharmaceutical performance following oral administration. Several cell and tissue-based in vitro and ex vivo models have been developed over the years, with the intention to realistically mimic pulmonary biological barriers. It is the aim of this review to critically discuss the available models regarding their advantages and limitations and to elaborate further which biopharmaceutical questions can and cannot be answered using the existing models.

Efficacy of atropine and scopolamine on airway contractions following exposure to the nerve agent VX

Nerve agents are highly toxic organophosphorus compounds that inhibit acetylcholinesterase resulting in rapid accumulation of the neurotransmitter acetylcholine (ACh) causing a cholinergic syndrome including respiratory failure. In the present study, respiratory responses and antimuscarinic treatment efficacy was evaluated ex vivo using rat precision-cut lung slices (PCLS) exposed to the nerve agent VX. The respiratory effects were evaluated either by adding exogenous ACh directly to the culture medium or by applying electric-field stimulation (EFS) to the PCLS to achieve a release of endogenous ACh from neurons in the lung tissue. The airway contraction induced by both methods was enhanced by VX and resulted in lingering airway recovery, in particular when airways were exposed to a high VX-dose. Both contractions induced by EFS and exogenously added ACh were significantly reduced by administration of the antimuscarinic drugs atropine or scopolamine. Two additions of atropine or scopolamine after maximal ACh-induced airway response was demonstrated effective to reverse the contraction. By adding consecutive doubled doses of antimuscarinics, high efficiency to reduce the cholinergic airway response was observed. However, the airways were not completely recovered by atropine or scopolamine, indicating that non-muscarinic mechanisms were involved in the smooth muscle contractions. In conclusion, it was demonstrated that antimuscarinic treatment reversed airway contraction induced by VX but supplemental pharmacological interventions are needed to fully recover the airways. Further studies should therefore clarify the mechanisms of physiological responses in lung tissue following nerve agent exposures to improve the medical management of poisoned individuals.

Breathomics in Asthmatic Children Treated with Inhaled Corticosteroids

BACKGROUND

"breathomics" enables indirect analysis of metabolic patterns underlying a respiratory disease. In this study, we analyze exhaled breath condensate (EBC) in asthmatic children before (T0) and after (T1) a three-week course of inhaled beclomethasone dipropionate (BDP).

METHODS

we recruited steroid-naive asthmatic children for whom inhaled steroids were indicated and healthy children, evaluating asthma control, spirometry and EBC (in asthmatics at T0 and T1). A liquid-chromatography-mass-spectrometry untargeted analysis was applied to EBC and a mass spectrometry-based target analysis to urine samples.

RESULTS

metabolomic analysis discriminated asthmatic (n = 26) from healthy children (n = 16) at T0 and T1, discovering 108 and 65 features relevant for the discrimination, respectively. Searching metabolomics databases, seven putative biomarkers with a plausible role in asthma biochemical-metabolic processes were found. After BDP treatment, asthmatic children, in the face of an improved asthma control (p < 0.001) and lung function (p = 0.01), showed neither changes in EBC metabolomic profile nor in urinary endogenous steroid profile.

CONCLUSIONS

"breathomics" can discriminate asthmatic from healthy children, with prostaglandin, fatty acid and glycerophospholipid as putative markers. The three-week course of BDP-in spite of a significant clinical improvement-was not associated with changes in EBC metabolic arrangement and urinary steroid profile.

Advances with glucocorticoids in the treatment of asthma: state of the art

INTRODUCTION

Asthma is one of the most frequent chronic diseases all over the world. Glucocorticoids (GCs), both inhaled (ICSs) and oral (OCSs), are the most effective treatment in asthma because they control symptoms and prevent exacerbations.

AREAS COVERED

The present article reviews the new therapeutic indications of GCs for the treatment of asthma and focuses on new molecules and safety issues.

EXPERT OPINION

Most patients with asthma benefit from corticosteroid-based treatments. Side effects are mainly due to prolonged use of oral GCs, while they are minor with inhaled GCs. Interesting insights come from the new ICSs, which are characterized by lower oral bioavailability and higher lipophilicity and are more effective with less side effects. Recent trials have shown the efficacy of early use of ICSs in mild asthma. Furthermore, the possibility to prescribe targeted therapies using specific biomarkers in steroid-sensitive asthma can reduce doses and duration of treatment, while biological agents should be reserved for non-responding patients. All this evidence confirm the need to continue on the path toward precision medicine, in which the treatments are based on clinical and molecular traits.

Antiinflammatory Effects of Budesonide in Human Fetal Lung

Lung inflammation in premature infants contributes to the development of bronchopulmonary dysplasia (BPD), a chronic lung disease with long-term sequelae. Pilot studies administering budesonide suspended in surfactant have found reduced BPD without the apparent adverse effects that occur with systemic dexamethasone therapy. Our objective was to determine budesonide potency, stability, and antiinflammatory effects in human fetal lung. We cultured explants of second-trimester fetal lung with budesonide or dexamethasone and used microscopy, immunoassays, RNA sequencing, liquid chromatography/tandem mass spectrometry, and pulsating bubble surfactometry. Budesonide suppressed secreted chemokines IL-8 and CCL2 (MCP-1) within 4 hours, reaching a 90% decrease at 12 hours, which was fully reversed 72 hours after removal of the steroid. Half-maximal effects occurred at 0.04-0.05 nM, representing a fivefold greater potency than for dexamethasone. Budesonide significantly induced 3.6% and repressed 2.8% of 14,500 sequenced mRNAs by 1.6- to 95-fold, including 119 genes that contribute to the glucocorticoid inflammatory transcriptome; some are known targets of nuclear factor-κB. By global proteomics, 22 secreted inflammatory proteins were hormonally regulated. Two glucocorticoid-regulated genes of interest because of their association with lung disease are CHI3L1 and IL1RL1. Budesonide retained activity in the presence of surfactant and did not alter its surface properties. There was some formation of palmitate-budesonide in lung tissue but no detectable metabolism to inactive 16α-hydroxy prednisolone. We concluded that budesonide is a potent and stable antiinflammatory glucocorticoid in human fetal lung in vitro, supporting a beneficial antiinflammatory response to lung-targeted budesonide:surfactant treatment of infants for the prevention of BPD.

Long-Term Fluticasone Propionate/Formoterol Fumarate Combination Therapy Is Associated with a Low Incidence of Severe Asthma Exacerbations

BACKGROUND

A primary goal of asthma management is the reduction of exacerbation risk. We assessed the occurrence of oral corticosteroid-requiring exacerbations (OCS exacerbations) with long-term fluticasone/formoterol therapy, and compared it with the occurrence of similar events reported with other inhaled corticosteroid/long acting β2-agonist (ICS/LABA) combinations.

METHODS

The occurrence of OCS exacerbations was assessed in two open-label trials of fixed-dose fluticasone/formoterol administered for between 26 to 60 weeks in adults and adolescents with asthma. The incidence of OCS exacerbations with fluticasone/formoterol was compared with those reported in three recent Cochrane meta-analyses of other ICS/LABAs.

RESULTS

The pooled incidence of OCS exacerbations with long-term fluticasone/formoterol was 2.1% (95% CI: 1.1, 3.2%, n/N = 16/752). In only two of the nineteen treatment arms summarized by Cochrane did OCS exacerbation incidence approximate that seen in the two fluticasone/formoterol trials (single-inhaler fluticasone/salmeterol [2.9%]; separate inhaler budesonide, beclometasone, or flunisolide plus formoterol [3.4%]). In Lasserson's review the pooled incidence of OCS exacerbations for single-inhaler combinations was 9.5% (95% CI: 8.4, 10.6%; n/N = 239/2516) for fluticasone/salmeterol, and 10.6% (95% CI: 9.3, 11.8%; n/N = 257/2433) for budesonide/formoterol. In Ducharme's and Chauhan's meta-analyses (primarily incorporating separate inhaler combinations [fluticasone, budesonide, beclometasone, or flunisolide plus salmeterol or formoterol]), the pooled incidences of OCS exacerbations were 16.0% (95% CI: 14.2, 17.8%, n/N = 258/1615) and 16.7% (95% CI: 14.9, 18.5, n/N = 275/1643), respectively.

CONCLUSIONS

The incidence of exacerbations in two fixed-dose fluticasone/formoterol studies was low and less than in the majority of comparable published studies involving other ICS/LABA combinations. This difference could not be readily explained by differences in features of the respective studies and may be related to the favorable pharmacological/mechanistic characteristics of the constituent components fluticasone and formoterol compared to other drugs in their respective classes.

Ciclesonide: A Pro-Soft Drug Approach for Mitigation of Side Effects of Inhaled Corticosteroids

Inhaled corticosteroids are used as one of the first-line drug therapy in patients with asthma. However, their long-term use is associated with various oropharyngeal and systemic side and adverse effects. Design of pro-soft drug is one of the strategies, which was adopted in the design of ciclesonide for mitigation of side effects usually observed with the use of inhaled corticosteroids. Ciclesonide, a pro-soft drug, is converted to an active metabolite desisobutyryl-ciclesonide in the lungs. The anti-inflammatory effect of desisobutyryl-ciclesonide is much higher than ciclesonide, and therefore, the local effect of the metabolite is higher with lower systemic side effects. Ciclesonide has favorable pharmacokinetic and pharmacodynamic properties as inhaled corticosteroid including low oral bioavailability, high plasma protein binding and rapid systemic clearance, high pulmonary deposition and distribution and long pulmonary residence duration. These advantageous properties make ciclesonide a very effective treatment option with low side effects. Various clinical studies support safety and efficacy of ciclesonide use in mild, moderate, and severe asthma patients.

Ethnic differences in adverse drug reactions to asthma medications: a systematic review

BACKGROUND

Information on ethnic diversity of adverse drug reactions (ADRs) to asthma medications is rare despite evidence suggesting higher risk for African Americans when using β2-adrenergic receptor agonists. The objectives are to investigate how ethnic background was involved in ADR assessment and to examine the relationship between ethnic background and ADRs to asthma medications.

METHODS

MEDLINE was searched until March 2014. All types of studies reporting ADRs to asthma medications involving more than one ethnic group were included. Extracted information includes study designs, ethnic backgrounds, intervention, and types and severities of ADRs.

RESULTS

Among the selected 15 randomised clinical trials, six pooled analyses of randomized clinical trials, and five prospective observational studies, only six studies compared ADRs across different ethnic groups. The majority of the comparisons were either statistically insignificant or inconclusive.

CONCLUSIONS

Ethnicity was largely overlooked. Most studies neglected to report ADRs by ethnicity. Lack of consistency in defining ethnicities complicated further pooled analyses. Despite the higher prevalence of asthma among specific ethnic minority groups, few studies disaggregated information by ethnic background, and reports of ADRs to asthma medications in different ethnic groups were rare. We suggest that the inclusion of ADR analysis by different ethnic backgrounds is desirable.

"Target-Site" Drug Metabolism and Transport

The recent symposium on "Target-Site" Drug Metabolism and Transport that was sponsored by the American Society for Pharmacology and Experimental Therapeutics at the 2014 Experimental Biology meeting in San Diego is summarized in this report. Emerging evidence has demonstrated that drug-metabolizing enzyme and transporter activity at the site of therapeutic action can affect the efficacy, safety, and metabolic properties of a given drug, with potential outcomes including altered dosing regimens, stricter exclusion criteria, or even the failure of a new chemical entity in clinical trials. Drug metabolism within the brain, for example, can contribute to metabolic activation of therapeutic drugs such as codeine as well as the elimination of potential neurotoxins in the brain. Similarly, the activity of oxidative and conjugative drug-metabolizing enzymes in the lung can have an effect on the efficacy of compounds such as resveratrol. In addition to metabolism, the active transport of compounds into or away from the site of action can also influence the outcome of a given therapeutic regimen or disease progression. For example, organic anion transporter 3 is involved in the initiation of pancreatic β-cell dysfunction and may have a role in how uremic toxins enter pancreatic β-cells and ultimately contribute to the pathogenesis of gestational diabetes. Finally, it is likely that a combination of target-specific metabolism and cellular internalization may have a significant role in determining the pharmacokinetics and efficacy of antibody-drug conjugates, a finding which has resulted in the development of a host of new analytical methods that are now used for characterizing the metabolism and disposition of antibody-drug conjugates. Taken together, the research summarized herein can provide for an increased understanding of potential barriers to drug efficacy and allow for a more rational approach for developing safe and effective therapeutics.

Microbial biotransformation of beclomethasone dipropionate by Aspergillus niger

In the present research, the steroidal anti-asthmatic drug beclomethasone dipropionate was subjected to microbial biotransformation by Aspergillus niger. Beclomethasone dipropionate was transformed into various metabolites first time from microbial transformation. New drug metabolites produced can act as new potential drug molecules and can replace the old drugs in terms of safety, efficacy, and least resistance. They were purified by preparative thin layer chromatography technique, and their structures were elucidated using modern spectroscopic techniques, such as 13C NMR, 1H NMR, HMQC, HMQC, COSY, and NOESY, and mass spectrometry, such as EI-MS. Four metabolites were purified: (i) beclomethasone 17-monopropionate, (ii) beclomethasone 21-monopropionate, (iii) beclomethasone, and (iv) 9beta,11beta-epoxy-17,21-dihydroxy-16beta-methylpregna-1,4-diene-3,20-dione 21-propionate.

Influence of low-dose ritonavir with and without darunavir on the pharmacokinetics and pharmacodynamics of inhaled beclomethasone

OBJECTIVE

To identify an alternative inhaled corticosteroid to fluticasone propionate that can be safely coadministered with HIV protease inhibitors, the safety and pharmacokinetics of beclomethasone dipropionate (BDP) and its active metabolite, beclomethasone 17-monopropionate (17-BMP), in combination with ritonavir (RTV) and darunavir/ritonavir (DRV/r) were assessed.

DESIGN

Open-label, prospective, randomized pharmacokinetic and pharmacodynamic study in healthy volunteers.

METHODS

Thirty healthy volunteers received inhaled 160 μg bid BDP for 14 days and were then randomized (1:1:1) into 3 groups: group 1 (control) remained on BDP alone for 28 days, group 2 received 100 mg bid BDP + RTV for 28 days, and group 3 received 600/100 mg bid BDP + DRV/r for 28 days. Pharmacokinetic sampling for 17-BMP was performed on days 14 and 28, and pharmacokinetic parameter values were compared within patients and between groups. Cortisol stimulation testing was also performed on days 1, 14, 28, and 42 and compared within and between groups.

RESULTS

Geometric mean ratios (day 28:day 14) (90% confidence interval) for 17-BMP area under the concentration-time curve in groups 1, 2, and 3, respectively, were 0.93 (0.81 to 1.06, P = 0.27), 2.08 (1.52 to 2.65, P = 0.006), and 0.89 (0.68 to 1.09, P = 0.61). There were no significant reductions in serum cortisol levels within or between groups (P > 0.05).

CONCLUSIONS

DRV/r did not increase 17-BMP exposure, whereas RTV alone produced a statistically significant but clinically inconsequential 2-fold increase in 17-BMP exposure. Adrenal suppression was not observed in any of the study groups. These data suggest that BDP can be safely coadministered with DRV/r and likely other RTV-boosted protease inhibitors.

Clinical pharmacokinetic and pharmacodynamic profile of inhaled ciclesonide

Asthma is a chronic inflammatory disease of the airways, and inhaled corticosteroids (ICSs) are recommended as first-line therapy for persistent asthma of all severities. Ciclesonide is a novel ICS, which is administered as an aerosol solution in a metered-dose inhaler, using hydrofluoroalkane-134a as a propellant. Because of the high respirable particle fraction, high pulmonary deposition is obtained in patients, which constitutes the basis of effective therapeutic action. The parent compound, ciclesonide, is pharmacologically inactive and is activated in the target organ, the lung, to form its only pharmacologically active metabolite, desisobutyryl-ciclesonide (des-CIC). Low oral deposition combined with minimal formation of des-CIC in the oropharynx may minimize the typical oropharyngeal adverse events associated with ICSs. Low oral bioavailability, rapid clearance and high protein binding reduce pharmacologically relevant systemic exposure. The unique pharmacokinetic and pharmacodynamic profile of ciclesonide offers a rationale that supports the favourable risk-benefit profile observed in clinical trials in patients with persistent asthma.

Demographic data in asthma clinical trials: a systematic review with implications for generalizing trial findings and tackling health disparities

The prevalence of asthma, and the morbidity, adverse events, mortality and healthcare utilisation of asthmatic patients vary widely among racial/ethnic and other socio-demographic groups. Debates over the meanings of race and ethnicity and the strategic need to resolve health inequalities have prompted extensive recommendations for reporting and analyzing racial/ethnic and demographic information in clinical trials. We conducted a systematic review to determine the extent to which race/ethnicity, socio-economic status and other demographic variables are analyzed and reported in publications from randomized controlled trials of asthma interventions. Randomized controlled trials of inhaled corticosteroids and long-acting beta-agonists in asthmatic patients were identified by systematically searching 12 electronic bibliographic databases. We identified peer-reviewed papers reporting 87 relevant trials published during 1985-2006, from which we extracted data on patients' race/ethnicity, ancestry, gender, socio-economic variables and geographical attributes. The proportion of the papers reporting the race/ethnicity of their participants was lower than would be expected by chance and has recently declined. None of the papers included race/ethnicity or gender in statistical analyses or reported socio-economic variables, ancestry, or genetic data for their participants, and few discussed the generalizability of their findings. The frequency of reporting race/ethnicity was statistically significantly lower in trials conducted in the UK than in the US, but 23 of the 87 papers did not identify countries. Despite extensive recommendations in the literature, guidance from health agencies on analyzing and reporting demographic data in clinical trials still appears inconsistent and vague. There remains a need to improve guidance on the representation and analysis of minority populations in asthma clinical trials, in order to encourage transparent reporting of population selection, analysis approaches, and trial generalizability. To assist this process, asthma clinical trials should be based on clear hypotheses that link both to existing demographic evidence and to demographic healthcare goals.

Ciclesonide: a safe and effective inhaled corticosteroid for the treatment of asthma

Ciclesonide is a novel inhaled corticosteroid used in the continuous treatment of mild-to-severe asthma. Its formulation and mechanism of action yield a low oral and systemic bioavailability, and high pulmonary deposition. In multiple clinical trials, ciclesonide is at least as effective as either fluticasone propionate or budesonide at symptom control, while in many cases having improved safety outcomes and tolerability. The improved safety and comparable efficacy profiles of ciclesonide demonstrated in current studies could potentially yield a treatment option that may lead to improved adherence and outcome.

Ciclesonide: a review of its use in the management of asthma

Ciclesonide (Alvesco) is an inhaled corticosteroid used in the preventative treatment of persistent bronchial asthma in adults, adolescents and, in some countries, children. The drug is delivered by a non-chlorofluorocarbon hydrofluoroalkane (HFA) metered-dose inhaler (MDI). In the lungs, ciclesonide is converted to an active metabolite, which is responsible for the beneficial effects of the drug in patients with asthma. Ciclesonide and its active metabolite have low systemic bioavailability and therefore have a low potential to produce systemic adverse events. Inhaled ciclesonide delivered by HFA-MDI is effective in the prophylactic treatment of persistent asthma in adults, adolescents and children, and is generally well tolerated. In general, ciclesonide improves lung function and reduces asthma symptoms and rescue medication use in adults and adolescents with asthma of varying severity. The drug is generally no less effective than other inhaled corticosteroids with regard to maintaining or improving lung function and may have a more favourable tolerability profile than some other agents in this class. Ciclesonide has also shown efficacy in paediatric patients with asthma. Data on its long-term effects on other clinical outcomes, such as asthma exacerbations, would be of interest. Further comparative and long-term studies would also be beneficial in order to definitively position ciclesonide with respect to other inhaled corticosteroids. In the meantime, ciclesonide offers an effective and well tolerated first-line preventative treatment option for persistent asthma.

Metabolism of ciclesonide in the upper and lower airways: review of available data

Ciclesonide is a novel corticosteroid (CS) for the treatment of asthma and allergic rhinitis. After administration, the parent compound ciclesonide is converted by intracellular airway esterases to its pharmacologically active metabolite desisobutyryl-ciclesonide (des-CIC). We investigated the in vitro activation of ciclesonide and further esterification of des-CIC to (mainly) des-CIC oleate in several human target organ test systems. Human precision-cut lung slices, alveolar type II epithelial cells (A549), normal bronchial epithelial cells (NHBE), and nasal epithelial cells (HNEC) were incubated with ciclesonide. Enzymes characterization and the determination of the reversibility of fatty acid esterification was investigated in HNEC and NHBE. Ciclesonide was taken up and converted to des-CIC in all cellular test systems. Intracellular concentrations of des-CIC were maintained for up to 24 h. Formation of des-CIC oleate increased over time in HNEC, A549 cells, and lung slices. The formed des-CIC fatty acid conjugates were reconverted to des-CIC. Increasing concentrations of carboxylesterase and cholinesterase inhibitors progressively reduced the formation of metabolites. The results derived from these studies demonstrate the activation of ciclesonide to des-CIC in the upper and lower airways. The reversible formation of des-CIC fatty acid conjugates may prolong the anti-inflammatory activity of des-CIC and may allow for once-daily dosing.