Budesonide fatty-acid esterification: a novel mechanism prolonging binding to airway tissue. Review of available data

Budesonide aqueous nasal spray: an updated review in managing chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a frequent medical condition. Type 2 inflammation signs CRSwNP in western countries. Type 2 inflammation leads to nasal airflow limitation. Budesonide aqueous nasal spray (BANS) is an intranasal corticosteroid (INCS); it has been launched in the early 1980s. BANS is indicated for treating allergic rhinitis, nonallergic rhinitis, and nasal polyps (both as treatment and prevention after surgery). Consolidated evidence documented its efficacy in treating CRSwNP. In addition, BANS is safe with negligible local and systemic side effects. Recent guidelines for patients with CRSwNP recommend using INCS as the first line in many situations. In particular, patients may assess the perception of symptoms' severity using the Visual Analog Scale (VAS). A score >5/10 means uncontrolled symptoms in both diseases and requires adequate treatment. BANS could appropriately be used in patients with uncontrolled symptoms and/or moderate/severe nasal obstruction. In addition, BANS may adequately integrate surgery and biologics for CRSwNP management. In conclusion, BANS represents a valuable option in managing patients with type 2-mediated CRSwNP.

Budenoside aqueous nasal spray: an updated reappraisal in rhinitis management

Allergic rhinitis (AR) and nonallergic rhinitis are prevalent diseases. In western countries, type 2 inflammation usually characterizes these medical conditions and mainly sustains nasal obstruction. Budesonide aqueous nasal spray (BANS) is an intranasal corticosteroid (INCS) that has been available since the early 1980s. BANS is indicated for treating allergic rhinitis, nonallergic rhinitis, and nasal polyps (both as treatment and prevention after surgery). Consolidated evidence confirms its efficacy in treating seasonal and perennial AR, and nonallergic rhinitis. In addition, BANS is safe with negligible local and systemic side effects. Recent guidelines for patients with AR recommend using INCS as the first line in many situations. In particular, patients may assess the perception of symptoms' severity using the Visual Analog Scale. A score ≥5/10 means uncontrolled symptoms and requires adequate treatment. BANS could appropriately be used in patients with uncontrolled symptoms and/or moderate/severe nasal obstruction. In conclusion, BANS represents a valuable option in managing patients with type 2 inflammation of the nose.

May a different kinetic mode explain the high efficacy/safety profile of inhaled budesonide?

The claimed functional basis for ICSs in asthma and COPD is airway selectivity, attained by inhaling a potent, lipophilic compound with long local dissolution/absorption time. The development has been empirically based, resulting in five widely used ICSs. Among them, budesonide (BUD) deviates by being less lipophilic, leading to a more rapid systemic uptake with plasma peaks with some systemic anti-inflammatory activity. By this, BUD fits less well into the current pharmacological dogma of optimal ICS profile. In this review we compared the physicochemical, pharmacological and clinical properties of BUD, fluticasone propionate (FP) and fluticasone furoate (FF), representing different levels of lipophilicity, airway and systemic kinetics, focusing on their long-acting β2-agonist (LABA) combinations, in line with current GINA and GOLD recommendations. We are aware of the differences between formoterol (FORM) and the not rapid acting LABAs such as e.g. salmeterol and vilanterol but our comparisons are based on currently available combination products. A beclomethasone dipropionate (BDP)/FORM combination is also commented upon. Based on clinical comparisons in asthma and COPD, we conclude that the BUD/formoterol (BUD/FORM) combination is as effective and safe as the FP and FF combinations, and is in some cases even better as it can be used as "maintenance plus reliever therapy" (MART) in asthma and as maintenance in COPD. This is difficult to explain by current views of required ICS's/LABAs pharmacokinetic profiles. We propose that BUD achieves its efficacy by a combination of airway and systemic activity. The airway activity is dominating. The systemic activity contributes by plasma peaks, which are high enough for supportive anti-inflammatory actions at the blood and bone marrow levels but not sufficiently long to trigger a similar level of systemic adverse effects. This may be due to BUD's capacity to exploit a systemic differentiation mechanism as programmed for cortisol's various actions. This differentiation prospect can be reached only for an ICS with short plasma half-life. Here we present an alternative mode for an ICS to reach combined efficacy and safety, based on a poorly investigated and exploited physiological mechanism. A preference of this mode is broader versatility, due to that its straighter dose-response should allow a better adaptation to disease fluctuations, and that its rapid activity enables use as "anti-inflammatory reliever".

Quantitative Assessment of Pulmonary Targeting of Inhaled Corticosteroids Using Ex Vivo Receptor Binding Studies

The goal of locally acting inhaled corticosteroids is to achieve distinct pulmonary effects with reduced systemic side effects. The present work using an ex vivo receptor binding model in rats was interested in assessing pulmonary targeting for several commercially available corticosteroids by monitoring receptor occupancies in the lung and systemic organs (liver, kidney, spleen, and brain) after intravenous (IV) injection or intratracheal (IT) instillation of a dry powder administration at a dose of 100 μg/kg. Pulmonary targeting, defined as the difference in cumulative receptor occupancies (AUC_E) between the lung and kidney after pulmonary delivery, differed across the investigated corticosteroids (ΔAUC_E range, 33 ± 46 to 143 ± 52% *h) with the highest degree found for corticosteroids with high systemic clearance and pronounced lipophilicity (presumably allowing a long pulmonary residence time). Additionally, this study demonstrated differences in the receptor occupancies across systemic organs. Using kidney receptor occupancies as the comparator, liver receptor occupancies were reduced (ΔAUC_E range: - 157 ± 43 to 178 ± 42% *h) after IV and IT administration for corticosteroids with high intrinsic clearance, while they were increased for corticosteroid prodrugs due to hepatic activation. Spleen receptor occupancies were increased after IT (ΔAUC_E range: 33 ± 35 to 135 ± 28% *h), but not after IV administration. This was especially true for slowly dissolving drugs. Reduced brain uptake was also observed for ciclesonide (CIC) and des-ciclesonide (desCIC), two compounds previously not investigated. In summary, ex vivo receptor binding studies represent a powerful tool to assess the fate of ICSs.

Benefit:Risk Profile of Budesonide in Obstructive Airways Disease

Airway inflammation is a major contributing factor in both asthma and chronic obstructive pulmonary disease (COPD) and represents an important target for treatment. Inhaled corticosteroids (ICS) as monotherapy or in combination therapy with long-acting β2-agonists or long-acting muscarinic antagonists are used extensively in the treatment of asthma and COPD. The development of ICS for their anti-inflammatory properties progressed through efforts to increase topical potency and minimise systemic potency and through advances in inhaled delivery technology. Budesonide is a potent, non-halogenated ICS that was developed in the early 1970s and is now one of the most widely used lung medicines worldwide. Inhaled budesonide's physiochemical and pharmacokinetic/pharmacodynamic properties allow it to reach a rapid and high airway efficacy due to its more balanced relationship between water solubility and lipophilicity. When absorbed from the airways and lung tissue, its moderate lipophilicity shortens systemic exposure, and its unique property of intracellular esterification acts like a sustained release mechanism within airway tissues, contributing to its airway selectivity and a low risk of adverse events. There is a large volume of clinical evidence supporting the efficacy and safety of budesonide, both alone and in combination with the fast- and long-acting β2-agonist formoterol, as maintenance therapy in patients with asthma and with COPD. The combination of budesonide/formoterol can also be used as an as-needed reliever with anti-inflammatory properties, with or without regular maintenance for asthma, a novel approach that is already approved by some country-specific regulatory authorities and currently recommended in the Global Initiative for Asthma (GINA) guidelines. Budesonide remains one of the most well-established and versatile of the inhaled anti-inflammatory drugs. This narrative review provides a clinical reappraisal of the benefit:risk profile of budesonide in the management of asthma and COPD.

On the pharmacokinetics of two inhaled budesonide/formoterol combinations in asthma patients using modeling approaches

Dry powder inhalers containing the budesonide/formoterol combination have currently a well-established position among other inhaled products. Even though their efficacy mainly depends on the local concentrations of the drug they deliver within the lungs, their safety profile is directly related to their total systemic exposure. The aim of the present investigation was to explore the absorption and disposition kinetics of the budesonide/formoterol combination delivered via two different dry powder inhalers in asthma patients. Plasma concentration-time data were obtained from a single-dose, crossover bioequivalence study in asthma patients. Non-compartmental and population compartmental approaches were applied to the available datasets. The non-compartmental analysis allowed for an initial characterization of the primary pharmacokinetic (PK) parameters of the two inhaled drugs and subsequently the bioequivalence assessment of the two different dry powder inhalers. The population pharmacokinetic analysis further explored the complex absorption and disposition characteristics of the two drugs. In case of inhaled FOR, a five-compartment PK model including an enterohepatic re-circulation process was developed. For inhaled BUD, the incorporation of two parallel first-order absorption rate constants (fast and slow) for lung absorption in a two-compartment PK model emphasized the importance of pulmonary anatomical features and underlying physiological processes during model development. The role of potential covariates on the variability of the PK parameters was also investigated.

Budesonide facilitates weaning from mechanical ventilation in difficult-to-wean very severe COPD patients: Association with inflammatory mediators and cells

INTRODUCTION

Mechanical ventilatory support is life-saving therapy for patients with respiratory failure in intensive care units (ICU) but is linked to ventilator-associated pneumonia and other nosocomial infections. Interventions that improve the efficiency of weaning from mechanical ventilation may improve patient outcomes.

OBJECTIVE

To determine whether inhaled budesonide decreases time-to-weaning in COPD stage 4 difficult-to-wean patients and reduces the release of pro-inflammatory cytokines in ICU patients.

MATERIALS AND METHODS

We recruited 55 difficult-to-wean COPD patients (Stage 4) within the ICU of the Masih Daneshvari Hospital. Subjects were randomly assigned to receive inhaled budesonide (0.5mg/day) or placebo (normal saline). Dynamic compliance and BAL cytokines were measured.

RESULTS

Budesonide significantly reduced the number of days on MV (days-to-weaning=4.6±1.6days) compared to that seen in the control group (7.2±2.7days, p=0.014). Dynamic compliance was significantly improved in the budesonide group on days 3 (p=0.018) and 5 (p=0.011) The levels of CXCL-8 and IL-6 diminished on days 3-5 after start of budesonide (p<0.05).

CONCLUSION

In COPD patients on MV, nebulized budesonide was associated with reduced BAL CXCL8 and IL-6 levels and neutrophil numbers as well as an improvement in ventilatory mechanics and facilitated weaning.

Scientific rationale for the possible inhaled corticosteroid intraclass difference in the risk of pneumonia in COPD

Inhaled corticosteroids (ICSs) treatment combined with long-acting β2-adrenoceptor agonists (LABAs) reduces the risk of exacerbations in COPD, but the use of ICSs is associated with increased incidence of pneumonia. There are indications that this association is stronger for fluticasone propionate than for budesonide. We have examined systematic reviews assessing the risk of pneumonia associated with fluticasone propionate and budesonide COPD therapy. Compared with placebo or LABAs, we found that fluticasone propionate was associated with 43%-78% increased risk of pneumonia, while only slightly increased risk or no risk was found for budesonide. We have evaluated conceivable mechanisms which may explain this difference and suggest that the higher pneumonia risk with fluticasone propionate treatment is caused by greater and more protracted immunosuppressive effects locally in the airways/lungs. These effects are due to the much slower dissolution of fluticasone propionate particles in airway luminal fluid, resulting in a slower uptake into the airway tissue and a much longer presence of fluticasone propionate in airway epithelial lining fluid.

Influence of respiratory tract disease and mode of inhalation on detectability of budesonide in equine urine and plasma

OBJECTIVE To evaluate the influence of respiratory tract disease (ie, recurrent airway obstruction [RAO]) and mode of inhalation on detectability of inhaled budesonide in equine plasma and urine samples. ANIMALS 16 horses (8 healthy control horses and 8 horses affected by RAO, as determined by results of clinical examination, blood gas analysis, bronchoscopy, and cytologic examination of bronchoalveolar lavage fluid). PROCEDURES 4 horses of each group inhaled budesonide (3 μg/kg) twice daily for 10 days while at rest, and the remaining 4 horses of each group inhaled budesonide during lunging exercise. Plasma and urine samples were obtained 4 to 96 hours after inhalation and evaluated for budesonide and, in urine samples, the metabolites 6β-hydroxybudesonide and 16α-hydroxyprednisolone. RESULTS Detected concentrations of budesonide were significantly higher at all time points for RAO-affected horses, compared with concentrations for the control horses. All samples of RAO-affected horses contained budesonide concentrations above the limit of detection at 96 hours after inhalation, whereas this was found for only 2 control horses. Detected concentrations of budesonide were higher, but not significantly so, at all time points in horses that inhaled budesonide during exercise, compared with concentrations for inhalation at rest. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that the time interval between inhalation of a glucocorticoid and participation in sporting events should be increased when inhalation treatment is administered during exercise to horses affected by respiratory tract disease.

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.

Newer glucocorticosteroids and corticosteroid resistance reversal in asthma

Inflammation is the hallmark of asthma. Glucocorticosteroids inhibit this inflammation and are the mainstay of therapy in asthma, however, they suffer from their own drawbacks. They possess high potency but their continued use has a negative influence on health. Hence, quest for a steroid with good potency but without the undesirable effects is ongoing. Besides, steroid resistance is a problem in a substantial proportion of severe asthmatics. Deeper insight into the molecular mechanism of this refractoriness has led to the successful trial of certain drugs to overcome this problem. This review attempts to discuss some of the patents related to improved glucocorticoids and those agents that have the potential to restore steroid sensitivity in severe asthmatics.

Real-world effects of two inhaled corticosteroid/long-acting β₂-agonist combinations in the treatment of asthma

OBJECTIVE

There are several inhaled corticosteroid/long-acting β2-agonist (ICS/LABA) combinations currently used to treat asthmatic patients, but the differences in the clinical effects of these ICS/LABAs are currently unknown. We herein evaluated the effects of two currently available ICS/LABA combinations in a real-world setting.

METHODS

A fluticasone propionate/salmeterol combined Discus inhaler (FP/SM; 250/50 μg bid) was switched to a budesonide/formoterol Turbuhaler inhaler (BUD/FM; 160/4.5 μg two inhalations bid) and FP/SM (500/50 μg bid) was also switched to BUD/FM (160/4.5 μg four inhalations bid) in symptomatic asthmatic patients treated with FP/SM over 20 years of age.

RESULTS

Sixty patients were enrolled in this study, and the scores of the asthma control test (ACT) and asthma control questionnaire-5 item version (ACQ5) were significantly improved 4 and 8 weeks after the switch to ICS/LABA treatments, and well-controlled asthma (ACQ5 score <0.75) and good control (ACT score >20) was achieved in 54 (90%) and 40 (66.7%) patients, respectively, at 8 weeks. The spirometric analysis revealed significant improvements of the values of the peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) after switching from FP/SM to BUD/FM, and significantly improved small airway impairments ([Formula: see text]50 and [Formula: see text]25) were observed in patients treated with high-dose ICS/LABA. These subjective and objective improvements were also seen in patients aged over 65 years old.

CONCLUSION

These data demonstrated that changing the combined ICS/LABA inhaler from FP/SM to BUD/FM can lead to more effective management of symptomatic patients with asthma, especially in patients treated with high-dose ICS/LABA.

Tissue accumulation kinetics of ciclesonide-active metabolite and budesonide in mice

Inhaled corticosteroids (ICS) are mainstay treatment of asthma and chronic obstructive pulmonary disease. However, highly lipophilic ICS accumulate in systemic tissues, which may lead to adverse systemic effects. The accumulation of a new, highly lipophilic ICS, ciclesonide and its active metabolite (des-CIC) has not yet been reported. Here, we have compared tissue accumulation of des-CIC and an ICS of a moderate lipophilicity, budesonide (BUD), after 14 days of once-daily treatment in mice. Single, three or 14 daily doses of [(3) H]-des-CIC or [(3) H]-BUD were administered subcutaneously to male CD1 albino mice, which were killed at 4 hr, 24 hr or 5 days after the last dose. Distribution of tissue concentration of radioactivity was studied by quantitative whole-body autoradiography. Pattern of radioactivity distribution across most tissues was similar for both corticosteroids after a single as well as after repeated dosing. However, tissue concentration of radioactivity differed between des-CIC and BUD. After a single dose, concentrations of radioactivity for both corticosteroids were low for most tissues but increased over 14 days of daily dosing. The tissue radioactivity of des-CIC at 24 hr and 5 days after the 14th dose was 2-3 times higher than that of BUD in majority of tissues. Tissue accumulation, assessed as concentration of tissue radioactivity 5 days after the 14th versus 3rd dose, showed an average ratio of 5.2 for des-CIC and 2.7 for BUD (p < 0.0001). In conclusion, des-CIC accumulated significantly more than BUD. Systemic accumulation may lead to increased risk of adverse systemic side effects during long-term therapy.

Comparison of budesonide/formoterol Turbuhaler with fluticasone/salmeterol Diskus for treatment effects on small airway impairment and airway inflammation in patients with asthma

BACKGROUND

A course of combination therapy with an inhaled corticosteroid (ICS) and a long-acting β(2) agonist (LABA) for asthma can improve lung function, asthma symptoms and reduce exacerbations. Because both medicinal substance and inhalation devices are associated with clinical efficacy, each ICS/LABA combination may have different features. This study aimed to compare the effects of two widely available formulations, budesonide/formoterol (BUD/FM) delivered by a Turbuhaler(®), and fluticasone/salmeterol (FP/SM) delivered by a Diskus(®), on small airway function and airway inflammation.

METHODS

Asthmatic patients (n = 40) treated twice daily with FP/SM 250/50 μg with forced expiratory volume in 1 s values controlled above 80% of the predicted normal but with suspected persistent airway inflammation and small airway impairment were enrolled in the study. Patients were randomized into two groups, receiving either twice daily BUD/FM 320/9 μg or FP/SM 250/50 μg, and treatment efficacy was compared after 4 weeks. Outcomes included impulse oscillometry (IOS), fractional exhaled nitric oxide (FeNO), spirometry and Asthma Control Questionnaire (ACQ) scores.

RESULTS

Patients in the BUD/FM group showed significant improvements in their IOS and spirometry parameters of small airway function, FeNO values and ACQ scores, compared with the FP/SM group. There were good correlations between IOS parameters, FeNO and ACQ score changes over the course of the treatment.

CONCLUSIONS

BUD/FM twice daily significantly improved small airway impairment and airway inflammation in asthmatic patients, leading to a reduction in asthma symptoms and achievement of good asthma control. In addition, improvement of small airway function may improve airway inflammation and/or lead to better controlled asthma.

Asthma: Chronopharmacotherapy and the molecular clock

Bronchial asthma is characterized by chronic airways inflammation and reversible airflow limitation. In patients with asthma, symptoms generally worsen during the early hours of the morning, and pulmonary function often deteriorates at the same time, suggesting a role for chronopharmacotherapy. Several drugs for asthma have been developed based on chronopharmacology. Most medications employed for the chronotherapy of asthma are administered once at night with the goal of preventing chronic airway inflammation or development of airflow limitation. In addition to bronchodilators, the inhaled glucocorticosteroid ciclesonide is now available with once-daily dosing, which also improves patients' compliance. Numerous investigations have demonstrated the usefulness of chronotherapy for asthma, especially for patients with nocturnal asthma. This review focuses on chronotherapy of asthma, and also provides a molecular biological explanation for the influence of asthma medications on the clock genes.

Development of budesonide microparticles using spray-drying technology for pulmonary administration: design, characterization, in vitro evaluation, and in vivo efficacy study

The purpose of this research was to generate, characterize, and investigate the in vivo efficacy of budesonide (BUD) microparticles prepared by spray-drying technology with a potential application as carriers for pulmonary administration with sustained-release profile and improved respirable fraction. Microspheres and porous particles of chitosan (drug/chitosan, 1:2) were prepared by spray drying using optimized process parameters and were characterized for different physicochemical parameters. Mass median aerodynamic diameter and geometric standard deviation for conventional, microspheres, and porous particles formulations were 2.75, 4.60, and 4.30 microm and 2.56, 1.75, and 2.54, respectively. Pharmacokinetic study was performed in rats by intratracheal administration of either placebo or developed dry powder inhalation (DPI) formulation. Pharmacokinetic parameters were calculated (Ka, Ke, T(max), C(max), AUC, and Vd) and these results indicated that developed formulations extended half life compared to conventional formulation with onefold to fourfold improved local and systemic bioavailability. Estimates of relative bioavailability suggested that developed formulations have excellent lung deposition characteristics with extended T(1/2) from 9.4 to 14 h compared to conventional formulation. Anti-inflammatory activity of BUD and developed formulations was compared and found to be similar. Cytotoxicity was determined in A549 alveolar epithelial cell line and found to be not toxic. In vivo pulmonary deposition of developed conventional formulation was studied using gamma scintigraphy and results indicated potential in vitro-in vivo correlation in performance of conventional BUD DPI formulation. From the DPI formulation prepared with porous particles, the concentration of BUD increased fourfold in the lungs, indicating pulmonary targeting potential of developed formulations.

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.

What is new in the management of childhood asthma?

The prevalence of asthma has increased in developed countries. The efficacy of available drugs in those with severe persistent disease is limited. This has led to a renewed search for the reasons for failures of the existing treatment and for novel concepts. Treatment with inhaled corticosteroids, and to a much lesser extent theophylline, can reduce the survival of inflammatory cells including eosinophils. Emerging trends in treatments for asthma could include strategies to alter the cytokine/chemokine balance. It is evident that the current ICS are already very efficient and safe, it will be difficult to introduce further improved formulations. Perhaps the most fruitful effort shall be in developing patient friendly easy to use targeted delivery systems. The newer therapies are planned for the several upstream targets and may have potential to prevent the disease. Various potential therapies are being worked upon like-targeting prevention of T cell activation, modulation of Th-1/Th-2 differentiation, inhibition of Th-2 related cytokines, Th-1/Th-2 modulation, inhibition of downstream mediators etc. The new strategy shall perhaps lie with matching the patients and their disease with the most suitable therapy.

Evidence of the in vivo esterification of budesonide in human airways

AIMS

Budesonide, unlike fluticasone propionate, undergoes fatty acid esterification in the lungs, and there is a need to characterize fully the distribution and fate of the two drugs after inhalation in humans.

METHODS

This open-label, randomized study was performed in adults undergoing whole lung or lobar resection resulting from lung cancer. Patients were given single 1000-mug doses of both budesonide and fluticasone propionate via dry powder inhalers before surgery. Tissue samples from peripheral and central lung, an ex vivo bronchial brush sample and intercostal muscle, together with plasma samples, were taken during surgery and analysed by liquid chromatography plus tandem mass spectrometry.

RESULTS

Lung tissue samples were obtained from 22 patients at surgery, 1-43 h after drug dosing. Budesonide was detectable from earliest sampling in central and peripheral lung tissue up to 10 h (in six of 22 samples), fluticasone propionate up to 22 h after inhalation (in 16 of 22 samples), and budesonide oleate up to 43 h after inhalation (in 21 of 22 samples). Budesonide, but not fluticasone propionate, was detected in intercostal muscle for up to 10 h after inhalation. Bronchial brush samples showed the presence of fluticasone propionate for up to 18 h, suggesting the presence of undissolved drug powder particles in the airway lumen.

CONCLUSION

Sustained retention of esterified budesonide in the lungs supports the prolonged duration of action of budesonide and suitability for once-daily administration.

Ciclesonide uptake and metabolism in human alveolar type II epithelial cells (A549)

Background

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.

Results

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.

Conclusion

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.

Pharmacokinetic and pharmacodynamic properties of inhaled ciclesonide

Inhaled corticosteroids are recommended first-line therapy for persistent asthma of all severities; however, oropharyngeal and systemic adverse events can be a concern. Inhaled corticosteroids exert their therapeutic and adverse effects by interacting with glucocorticoid receptors within and outside the lungs, respectively. Ciclesonide is a novel inhaled corticosteroid that possesses a unique pharmacokinetic and pharmacodynamic profile. Ciclesonide is inactive itself and converted to its pharmacologically active metabolite, desisobutyryl-ciclesonide, in the target organ, the lungs. Pulmonary activation combined with low oral deposition may minimize oropharyngeal adverse events, and low oral bioavailability, rapid clearance, and high protein binding may reduce systemic exposure. In addition, high pulmonary deposition due to the highly respirable particles, combined with the potential for prolonged lung retention via lipid conjugation, provides for effective therapeutic action.

Fluticasone given once versus twice a day: meta-analysis

OBJECTIVE

The aim of this study was to examine the efficacy of fluticasone administered once daily compared to twice daily in asthma.

METHODOLOGY

A meta-analysis was performed of randomized double-blind trials of at least 4 weeks duration that compared fluticasone administered once versus twice a day and presented data on at least one clinical outcome measure.

RESULTS

Six studies of 1517 children and adults with asthma met the inclusion criteria. Studies were predominantly in subjects with moderate asthma, treated with doses of fluticasone ranging from 200 to 500 microg per day. Twice-daily dosing was associated with significantly greater efficacy compared with once-daily dosing, for all outcome measures except night wakenings. The mean (95% CI) differences between twice and once-daily administration for FEV(1) and peak expiratory flow were 0.11 L (0.07-0.16) and 12.9 L/min (8.6-17.1), respectively. Twice-daily fluticasone was associated with significantly fewer withdrawals due to asthma than once-daily fluticasone, with an odds ratio of 0.44 (0.30-0.67).

CONCLUSION

The findings suggest that twice-daily administration of fluticasone will provide greater therapeutic benefit than a once-daily morning regimen.

Comparative pharmacology, bioavailability, pharmacokinetics, and pharmacodynamics of inhaled glucocorticosteroids

A comparison of the pharmacodynamics and pharmacokinetics of inhaled corticosteroids is necessary for their assessment. A good knowledge of these two aspects allows the optimization of efficacy and safety.The currently available inhaled corticosteroids already show some of the desired PK/PD parameters. The local adverse effects are decreased as soon as the inhaled corticosteroid is administered as an inactive prodrug or shows a bet-ter lung deposition. HFA-MDI beclomethasone dipropionate (BDP) and ciclesonide are two agents that illustrate this. Low oral bioavailability, rapid systemic clearance, and high plasma protein binding can minimize systemic adverse effects. Mometasone furoate, ciclesonide, and fluticasone propionate possess those characteristics. The pulmonary efficacy is maximized by high lung deposition and long pulmonary residence times. This effect can be achieved by slow dissolution in the lungs, as is the case for fluticasone propionate or lipid conjugation and has been shown for budesonide and ciclesonide. Furthermore, the lung deposition depends on the inhalation device, the particle size, and the inhalation technique. Therefore,improvement in the design of MDIs, DPIs, and nebulizers, and the development of more effective drug particles will lead to an optimized pulmonary targeting. Much progress has been made in the treatment of asthma. The available inhaled corticosteroids show a high safety profile and a good pulmonary selectivity. Development of newer compounds showed that improvement is possible as the result of a complete understanding of the PK/PD concepts. However,the introduction of further improved formulations with a better efficacy/safety profile will be difficult and protracted because the existing drugs are already highly efficient.

Budesonide-formoterol (inhalation powder) in the treatment of COPD

The budesonide-formoterol dry powder inhaler (Symbicort Turbuhaler 160/ 4.5-640/18 microg/day) contains the long-acting beta2-adrenoreceptor agonist formoterol and the inhaled corticosteroid budesonide. Two large, 12-month trials examined the effect of budesonide-formoterol 160/4.5 microg twice daily in COPD patients who met these criteria. The studies were identical, except one in which the patients had received oral prednisolone 30 mg/ day and had inhaled formoterol 4.5 microg twice daily for 2 weeks before randomization. In terms of the FEV1, budesonide-formoterol produced an effect greater than that of both budesonide alone and formoterol alone reported in previous studies. The combination was generally more effective than either of the components in terms of peak expiratory flow, symptoms, and exacerbations. These advantages of the combination over those of either budesonide alone or formoterol alone were quite consistent. Improving lung function and decreasing symptoms significantly, budesonide-formoterol combination therapy provides significant clinical improvements in COPD, despite the limited reversibility of impaired lung function in the disease.

Safety of inhaled corticosteroids: room for improvement

Inhaled corticosteroids (ICS) are the standard of care in asthma and are widely used in the treatment of patients with chronic obstructive pulmonary disease. High-dose regimens and long-term use of ICS in predisposed individuals may be associated with a variety of side effects, similar to those observed with systemic corticosteroid therapy. Side effects associated with long-term ICS use include reduction in growth velocity, cataracts, glaucoma, osteoporosis, and fractures. Fear of unwanted complications may be of concern in all patients using ICS, particularly in age- and gender-specific populations that are more prone to develop side effects or to reduce treatment adherence because of physical, behavioral, or psychological problems. In addition to concerns about ICS safety, dosing regimens that are difficult to follow may further reduce a patient's ability to comply with treatment. Ciclesonide, a new-generation ICS with unique pharmacokinetic properties, was developed to provide effective anti-inflammatory control for asthma with once-daily administration to improve patient adherence and a high safety profile to reduce the occurrence of local and systemic side effects.

The role of nebulized inhaled corticosteroid therapy in adult patients with asthma and chronic obstructive pulmonary disease

Conventional metered-dose inhalers and dry powder inhalers are used by most adult patients with asthma and chronic obstructive pulmonary disease who receive inhaled corticosteroid therapy. There are circumstances, however, in which nebulized inhaled corticosteroid delivery may provide greater clinical benefit to these patients. This review discusses the efficacy and safety of nebulized inhaled corticosteroid therapy in adult patients with asthma or chronic obstructive pulmonary disease for whom nebulized therapy may be preferable.

Budesonide once versus twice-daily administration: meta-analysis

OBJECTIVES

The aim of this study was to examine the efficacy of budesonide administered once daily compared to twice daily in asthma.

METHODOLOGY

Meta-analysis of randomised controlled trials comparing budesonide administered once versus twice a day that presented data on at least one clinical outcome measure was conducted.

RESULTS

A total of 10 studies, with 1922 children and adults with asthma, met the inclusion criteria. These studies were performed predominantly with mild to moderate asthmatic patients, using doses of budesonide ranging from 200 to 800 microg per day. There was no significant difference between daily dosing once or twice for all the clinical outcome variables, including withdrawals due to asthma, for which the odds ratio was 1.0 (95% confidence interval, 0.65-1.52).

CONCLUSIONS

In mild to moderate asthma a once-daily budesonide regimen has a similar efficacy to a twice-daily regimen in doses up to 800 microg per day. A once-daily regimen has potential advantages in terms of patient compliance and satisfaction, when used in clinical practice.

Once-daily inhaled budesonide for the treatment of asthma: clinical evidence and pharmacokinetic explanation

BACKGROUND

Budesonide, a widely used inhaled corticosteroid (ICS) with a favorable therapeutic ratio, is available via a dry powder inhaler (Pulmicort Turbuhaler) and as a suspension for nebulization (Pulmicort Respules).

METHODS

MEDLINE and an AstraZeneca database were searched to identify relevant controlled clinical trials published between 1986 and 2002 using the key words budesonide OR inhaled corticosteroid, AND once daily.

RESULTS

Thirty-four controlled clinical studies involving once-daily administration of budesonide to asthmatic patients were identified. Excluding long-term studies, this review presents data from 23 controlled studies for 4466 adults or adolescents and 1532 children with asthma and demonstrates efficacy of budesonide in both corticosteroid-naïve patients and patients previously treated with ICS. Once-daily administration of budesonide achieves clinical efficacy comparable with that of twice-daily regimens in patients with mild-to-moderate asthma and is equally effective when given in the morning or evening. Once-daily administration simplifies treatment regimens and may improve patient compliance. The tolerability profiles of budesonide once-daily via Turbuhaler or as budesonide inhalation suspension are good and comparable with those for twice-daily dosing.

CONCLUSIONS

Once-daily budesonide is effective and well tolerated as initial treatment for adults and children with mild asthma and as maintenance therapy in patients with more severe asthma once asthma control has been achieved.

Pharmacokinetics of budesonide (Entocort EC) capsules for Crohn's disease

This overview summarises available pharmacokinetic data on budesonide capsules (Entocort EC), approved for the treatment of mild-to-moderate active Crohn's disease involving the ileum and/or ascending colon and for prolongation of symptom control. Budesonide is a locally-acting glucocorticosteroid with an extensive, primarily hepatic, metabolism after oral administration. It is rapidly absorbed and biotransformed by cytochrome P450 (CYP) 3A to metabolites with negligible glucocorticoid activity. Entocort EC, a pH- and time-dependent oral formulation of budesonide, was developed to optimise drug delivery to the ileum and throughout the colon. Pharmaco-scintigraphic studies have confirmed that the Entocort EC formulation delays budesonide absorption and prolongs the rate of elimination but maintains complete absorption. This improves the delivery of budesonide to the intestinal lumen relative to a plain formulation. A low systemic availability of 9-21% indicates extensive first-pass elimination. Food appears to have little impact on the absorption of budesonide from Entocort EC capsules and the pharmacokinetics are dose-proportional between 3 and 15 mg. On average, systemic availability was 2.5-fold higher in patients with cirrhosis compared with healthy controls; however, mild liver impairment had little effect on systemic exposure. Pharmacokinetics appear unaffected by gender and age, although this has not been tested in younger children. Renal impairment is not expected to have an impact on the kinetics of Entocort EC. Budesonide is unlikely to inhibit the metabolism of other drugs, including CYP3A4 substrates, mainly because of the very low plasma concentrations obtained with the compound even after high doses of Entocort trade mark EC capsules. Strong CYP3A4 inhibitors, such as ketoconazole, will inhibit the metabolism of budesonide, resulting in several-fold increases in the area under the concentration-time curve of budesonide. Also, grapefruit juice intake may increase systemic availability of budesonide, probably by inhibition of intestinal CYP3A4 activity. Unlike prednisolone, oral contraceptives do not alter plasma budesonide concentrations. An increased pH obtained by gastric acid inhibitory drugs, such as omeprazole, does not affect the pharmacokinetics of budesonide. In summary, budesonide capsules (Entocort EC) possess many pharmacological features that make the formulation well adapted for a targeted treatment of inflammatory disorders, such as Crohn's disease involving the ileum and ascending colon.

Budesonide/formoterol: a review of its use in asthma

Budesonide and formoterol have been combined in a single dry powder device, Symbicort Turbuhaler (budesonide/formoterol 160/9-640/18 microg/day), in an effort to simplify asthma management. The efficacy of budesonide/formoterol as maintenance therapy in patients with asthma has been examined in several randomised studies.Twice-daily budesonide/formoterol was significantly more effective than an equivalent or higher daily dose of budesonide alone or high-dose fluticasone propionate alone at improving peak expiratory flow (PEF) in adults with predominantly moderate persistent asthma. Symptom control and the risk of mild exacerbations were significantly improved versus budesonide alone. Moreover, budesonide/formoterol appeared to be as effective as concurrent therapy with equivalent dosages of budesonide and formoterol administered via separate inhalers in adults with moderate persistent asthma. Budesonide/formoterol administered once daily was as effective as twice-daily administration (equivalent daily doses) and more effective than once-daily budesonide in adults with moderate persistent asthma. Twice-daily budesonide/formoterol significantly improved PEF compared with budesonide in paediatric patients with asthma. Adjustable maintenance dosing with budesonide/formoterol was associated with significantly less study drug use than fixed dosing with budesonide/formoterol in adults with predominantly mild or moderate persistent asthma. In two of three studies (all longer than 4 months' duration), the risk of exacerbations was significantly lower with adjustable than with fixed dosing, but no difference was detected in four short-term studies. Symptom severity was maintained or improved in most patients receiving either treatment regimen. In adults with moderate-to-severe persistent asthma, adjustable maintenance dosing with budesonide/formoterol reduced the rate of exacerbations and reliever medication use compared with fixed dosing with salmeterol/fluticasone propionate. Budesonide/formoterol was well tolerated in both fixed and adjustable dosing regimens. In conclusion, in patients with persistent asthma symptoms despite treatment with inhaled corticosteroids, budesonide/formoterol administered via a single dry powder Turbuhaler device is an effective, well tolerated, convenient treatment option, which may have the potential for improved compliance. It appears to be as effective as treatment with budesonide and formoterol administered via separate inhalers and is more effective than budesonide monotherapy in improving PEF, controlling symptoms and preventing mild exacerbations. Adjustable maintenance dosing with budesonide/formoterol is associated with a lower overall dosage and appears to maintain control as effectively as fixed dosing.

Detection and quantitation of fatty acid acyl conjugates of triamcinolone acetonide via gas chromatography-electron-capture negative-ion mass spectrometry

The inherent electron-capture properties of triamcinolone acetonide (TAA) fatty acid conjugates were exploited for development of a GC-MS technique for quantitation of C21 long-chain fatty esters of TAA synthesized in BEAS-2B cells, an immortalized airway epithelium cell line. TAA esters extracted from BEAS-2B cells were purified and detected via selected ion monitoring of the molecular anions generated from the TAA esters under electron-capture negative-ion mass spectrometric conditions. Standard curves were linear over a range of 0.0 to >4.5 ng/mg protein with r(2) values = 1. Levels of TAA conjugates extracted from BEAS-2B treated with 10(-5)M TAA for 24h ranged from 0.024 to 0.301 ng/mg protein. Further evidence for confirmation of the identity of TAA fatty esters formed in BEAS-2B cells was obtained via selected reaction monitoring. The transition monitored was formation of the carboxy anion generated from each of the respective molecular anions of the TAA esters during collision-induced decomposition. These findings indicate that the GC-MS analysis is suitable for studies of the kinetics of the TAA fatty acid conjugates formation in vitro and may be directly applicable to determination of the kinetics of TAA fatty acid conjugation in vivo.

Budesonide/formoterol: in chronic obstructive pulmonary disease

Budesonide/formoterol is a fixed-dose combination of the corticosteroid budesonide and the long-acting beta2-agonist formoterol, and is inhaled via the Turbuhaler device. In two large, randomised, double-blind, 12-month studies, patients with severe chronic obstructive pulmonary disease (COPD) receiving budesonide/formoterol 320/9 microg twice daily had a significantly higher forced expiratory volume in 1 second (FEV1) and significantly higher morning and evening peak expiratory flow at trial endpoint than recipients of budesonide or placebo; FEV1 was significantly higher than with formoterol in the larger study. In both studies, the rate of COPD exacerbations and exacerbations requiring oral corticosteroids was significantly reduced with budesonide/formoterol versus formoterol and placebo. Moreover, the time to first exacerbation was significantly prolonged with budesonide/formoterol versus all other treatment arms in the larger study. At 12 months, significant improvements in health-related quality-of-life scores were seen with budesonide/formoterol versus placebo in both studies. The reduction in total and individual symptom scores was significantly greater with budesonide/formoterol than with budesonide or placebo in the smaller study. Budesonide/formoterol was generally well tolerated by patients with severe COPD. The tolerability profile of the combination was similar to that of the individual components with no increase in the incidence of adverse events.

The role of budesonide in adults and children with mild-to-moderate persistent asthma

Asthma, a chronic and potentially life-threatening disease of the airways, affects patients of all ages. Inhaled corticosteroids (ICS) are the recommended first-line therapy for patients with persistent asthma. To review the clinical efficacy and tolerability data available on budesonide in the treatment of mild-to-moderate persistent asthma, a MEDLINE database search was performed for 1996-2003 using the following key words: budesonide, inhaled corticosteroid, efficacy, safety, systemic. When administered once or twice daily, budesonide effectively controls asthma in children, adolescents, and adults with mild-to-moderate asthma. Budesonide can be delivered effectively via a dry powder inhaler (Pulmicort Turbuhaler) in patients aged > or = 6 years or as an inhalation suspension (Pulmicort Respules) in children as young as 12 months. With over 20 years' clinical exposure, budesonide has been demonstrated to be well tolerated in the treatment of chronic asthma in patients as young as 12 months. Specifically, at doses required to treat mild or moderate persistent asthma, budesonide does not affect hypothalamic-pituitary-adrenal axis function, bone mineral density, cataract formation, or final adult height. As Pulmicort Turbuhaler, budesonide is the only ICS to achieve a Food and Drug Administration pregnancy category B rating. Early intervention with budesonide is recommended in asthma management: maximum benefit from therapy is reported in patients treated within 2 years of disease recognition. Budesonide is effective and well tolerated in the control of mild-to-moderate persistent asthma in patients aged 12 months and older. There is no evidence for variation in efficacy in population subgroups.

Equivalent asthma control and systemic safety of inhaled budesonide delivered via HFA-134a or CFC propellant in a broad range of doses

The aim of the present study was to demonstrate an equivalent asthma control and safety of inhaled budesonide 200 microg unit-dose via a spacer device (Jet Spacer, Chiesi Farmaceutici S.p.A.) given with an HFA-134a or CFC propellant in stable patients treated with inhaled corticosteroids. A total number of 270 patients, 134 in the HFA-134a group and 136 in the CFC group, completed a 2-week run-in period and were then randomised to receive a daily dose of inhaled budesonide (low dose: 400 microg, medium dose: 800 microg, high dose: 1200 or 1600 microg), defined on the basis of the dose of previous inhaled steroids given twice daily for 12 weeks. Morning and evening PEFR, intake of rescue salbutamol, number of day-time and night-time asthma attacks, number of night-time awakenings due to asthma and clinical symptoms were recorded daily by patients on diary cards. Pulmonary function tests (FEV1, FVC, PEFR and MEF50) and vital signs were measured at the clinics at study entry, at the start of treatment and after 2, 4, 8 and 12 weeks thereafter. Morning serum cortisol (8.00-10.00 AM) was measured at baseline and in the final visit. Adverse events and vital signs were recorded throughout the total study period. Small increases vs. baseline for lung function (more markedly in the high-dose subsets) and significant decreases of symptoms and use of rescue salbutamol were similarly observed in both groups. Equivalence was demonstrated for the primary endpoint morning PEFR (difference between means = -1.51 l/min; 95% CI: -9.40-6.37 l/min; pre-defined limits: +/- 42.16 l/min, i.e. +/- 10% of the reference LSM) as well as for evening PEFR and FEV1, both in the ITT population or on a per-protocol basis. No statistically significant differences between groups were observed in any of the other efficacy variables. A similar proportion of drug-related adverse events was observed in the two groups, without drug-related serious events in either group. No evidence of adrenal depletion was also noted with both propellants. In conclusion, the budesonide HFA-134a formulation given with a spacer device provided an equivalent asthma control with that of a corresponding CFC product, when administered in stable patients treated with inhaled corticosteroids in a broad range of daily doses. The use of the new propellant did not modify the safety profile of inhaled budesonide.

The role of intracellular esterification in budesonide once-daily dosing and airway selectivity

BACKGROUND

Since their introduction in the 1970s, inhaled corticosteroids (ICSs) have been used to control airway inflammation associated with asthma. Budesonide is one of the ICSs recommended as first-line therapy for mild to moderate persistent asthma.

OBJECTIVE

This article describes the esterification of budesonide and how it results in prolonged, location-specific retention of drug in the airways, allowing once-daily dosing.

RESULTS

Studies conducted over the past decade have shown that budesonide forms reversible fatty acid esters within the cells of airway tissue, resulting in the formation of an intracellular depot pool of inactive drug. As the intracellular concentration of free budesonide decreases, these budesonide esters are hydrolyzed back to their active state. This process increases budesonide's retention in the airways, prolongs its duration of action, and lowers the risk of systemic effects.

CONCLUSIONS

By extending budesonide's local anti-inflammatory effect and increasing its airway selectivity, the esterification process appears to contribute to the drug's efficacy, particularly during once-daily administration. Reducing the number of required daily inhalations may increase patient compliance with asthma therapy, although this remains to be evaluated.

Review of the unique properties of budesonide

BACKGROUND

The aim of inhaled corticosteroid (ICS) therapy for asthma is to attain high therapeutic activity in the airways while keeping the risk of systemic adverse effects relatively low. However, the physicochemical and pharmacokinetic properties of various ICSs affect this ratio, thereby influencing their ability to fulfill the requirements of an ideal agent.

OBJECTIVE

This article reviews the physical and pharmacokinetic properties of budesonide, outlining how they, safety data, and use of different inhalation devices enable budesonide to meet many of the clinical requirements of an ideal ICS for the treatment of asthma.

RESULTS

ICS efficacy is influenced by lipophilicity, lung deposition, and retention in airway tissue, whereas the rate of elimination determines systemic activity. Budesonide is retained in the airways to a greater extent than other ICSs because of an esterification process that increases its lipophilicity. The prolonged retention of budesonide in the airways may contribute to its efficacy when administered QD. In addition to a pressurized metered-dose inhaler, budesonide is available as a dry-powder inhaler and in nebulized form, which can be used by asthma patients aged > or =6 months.

CONCLUSIONS

When combined with delivery devices suitable for a spectrum of patient groups, the physical and pharmacokinetic properties of budesonide lend it many of the characteristics of an ideal ICS, including favorable efficacy and tolerability profiles.

Pharmaceutical characteristics that influence the clinical efficacy of inhaled corticosteroids

BACKGROUND

Inhaled corticosteroids (ICSs) are the most effective therapy for the management of persistent asthma. The aim of ICS therapy is to achieve a high anti-inflammatory effect in the airways with a concomitant low risk of unwanted local and systemic effects. Direct estimates of clinical efficacy and potency based on studies in humans are difficult to interpret.

OBJECTIVE

To examine the challenges of using alternative estimates of ICS efficacy and potency, including pharmaceutical characteristics.

DATA SOURCES AND STUDY SELECTION

Articles published from 1990 to 2002 on the potency, efficacy, and tolerability of ICSs were identified using MEDLINE and in-house databases and were then reviewed. Search terms included inhaled corticosteroid, budesonide, fluticasone, beclomethasone, mometasone, and potency.

RESULTS

Differences among ICSs can be readily shown using preclinical measures, such as glucocorticoid receptor binding or skin blanching tests. However, pharmaceutical (delivery and pharmacokinetic) differences of ICSs can have a greater impact on clinical efficacy than in vitro potency differences. For example, the unique esterification of budesonide in the airways prolongs its local activity and may contribute positively to its efficacy and therapeutic index. Although comparative clinical trials suggest 6-fold differences in potencies among ICSs, there is currently no evidence to support differences in efficacy when they are administered at equipotent dosages.

CONCLUSIONS

Greater preclinical potency of an ICS does not imply greater clinical efficacy. Pharmacokinetic factors can have a significant impact on relative clinical efficacy.