MicroED Structures of Fluticasone Furoate and Fluticasone Propionate Provide New Insights into Their Function

The detailed understanding of the conformational pathway of fluticasone, a widely prescribed medicine for allergic rhinitis, asthma, and chronic obstructive pulmonary disease (COPD), from formulation to its protein-bound state, has been limited due to a lack of access to its high-resolution structures. The three-dimensional (3D) structure of fluticasone furoate 1 remains unpublished, and the deposited structure of fluticasone propionate 2 could be further refined due to refinement against new data. We applied microcrystal electron diffraction (MicroED) to determine the 3D structures of 1 and 2 in their solid states. The preferred geometries in solution were predicted by using density functional theory (DFT) calculations. A comparative analysis of the structures of 1 and 2 across three states (in solid state, in solution, and protein-bound conformation) revealed the course of the conformational changes during the entire transition. Potential energy plots were calculated for the most dynamic bonds, uncovering their rotational barriers. This study underscores the combined use of MicroED and DFT calculations to provide a comprehensive understanding of conformational and energy changes during drug administration. The quantitative comparison also highlights the subtle structural differences that may lead to significant changes in the pharmaceutical properties.

MicroED Structures of Fluticasone Furoate and Fluticasone Propionate Provide New Insights to Their Function

The detailed understanding of fluticasone, a widely prescribed medicine for allergic rhinitis, asthma, and chronic obstructive pulmonary disease (COPD), has not been complete due to challenges in structural elucidation. The three-dimensional (3D) structure of fluticasone furoate 1 remained undetermined for decades, while the existing structures of fluticasone propionate 2 required refinement against improved data. In this study, we applied microcrystal electron diffraction (MicroED) to determine the 3D structures of 1 and 2 in their drug formulation state. Density functional theory (DFT) calculations were utilized to model solvent effects to determine the preferred geometries in solution. A comparative analysis of structures of 1 and 2 across three states (drug formulation state, in solution, and biologically active state) revealed major conformational changes during the entire transition. Potential energy plots were calculated for the most dynamic bonds, uncovering their rotational barriers. This study underscores the combined use of MicroED and DFT calculations to provide a comprehensive understanding of conformational and energy changes during drug functioning in humans. The quantitative comparison highlights the subtle structural differences that can lead to significant functional changes in pharmaceutical properties.

The use of inhaled corticosteroids in pediatric asthma: update

Despite the availability of several formulations of inhaled corticosteroids (ICS) and delivery devices for treatment of childhood asthma and despite the development of evidence-based guidelines, childhood asthma control remains suboptimal. Improving uptake of asthma management plans, both by families and practitioners, is needed. Adherence to daily ICS therapy is a key determinant of asthma control and this mandates that asthma education follow a repetitive pattern and involve literal explanation and physical demonstration of the optimal use of inhaler devices. The potential adverse effects of ICS need to be weighed against the benefit of these drugs to control persistent asthma especially that its safety profile is markedly better than oral glucocorticoids. This article reviews the key mechanisms of inhaled corticosteroid action; recommendations on dosage and therapeutic regimens; potential optimization of effectiveness by addressing inhaler technique and adherence to therapy; and updated knowledge on the real magnitude of adverse events.

Dry powder inhalers (DPIs)--a review of device reliability and innovation

A wide range of dry powder inhaler (DPI) devices are currently available on the market to deliver drugs into lungs with a view to maximise drug delivery with low variability. DPIs also face numerous clinical challenges, particularly related to variable patient factors such as age, clinical condition and inspiratory flow. Due to the drug formulation and the design of devices, different DPIs do not show the same performance and manufacturers are taking a variety of device design approaches. The characteristics of an ideal DPI, recent innovations in powder formulation and device design are not universally reliable in terms of dose variability, clinical efficacy, user friendliness and economy. This mini review examines whether device reliability is more important than innovation. This study enables a comparison of the relative merits of optimising existing DPIs or seeking to develop novel devices.

Fluticasone versus beclomethasone or budesonide for chronic asthma in adults and children

BACKGROUND

Beclomethasone dipropionate (BDP) and budesonide (BUD) are commonly prescribed inhaled corticosteroids for the treatment of asthma. Fluticasone propionate (FP) is newer agent with greater potency in in-vitro assays.

OBJECTIVES

To compare the efficacy and safety of Fluticasone to Beclomethasone or Budesonide in the treatment of chronic asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group trial register (January 2007) and reference lists of articles. We contacted trialists and pharmaceutical companies for additional studies and searched abstracts of major respiratory society meetings (1997 to 2006).

SELECTION CRITERIA

Randomised trials in children and adults comparing Fluticasone to either Beclomethasone or Budesonide in the treatment of chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed articles for inclusion and methodological quality. One reviewer extracted data. Quantitative analyses were undertaken using RevMan analyses 1.0.1.

MAIN RESULTS

Seventy-one studies (14,602 participants) representing 74 randomised comparisons met the inclusion criteria. Methodological quality was fair. Dose ratio 1:2: FP produced a significantly greater end of treatment FEV1 (0.04 litres (95% CI 0 to 0.07 litres), end of treatment and change in morning PEF, but not change in FEV1 or evening PEF. This applied to all drug doses, age groups, and delivery devices. No difference between FP and BDP/BUD were seen for trial withdrawals. FP led to fewer symptoms and less rescue medication use. When given at half the dose of BDP/BUD, FP led to a greater likelihood of pharyngitis. There was no difference in the likelihood of oral candidiasis. Plasma cortisol and 24 hour urinary cortisol was measured frequently but data presentation was limited. Dose ratio 1:1: FP produced a statistically significant difference in morning PEF, evening PEF, and FEV1 over BDP or BUD. The effects on exacerbations were mixed. There were no significant differences incidence of hoarseness, pharyngitis, candidiasis, or cough.

AUTHORS' CONCLUSIONS

Fluticasone given at half the daily dose of beclomethasone or budesonide leads to small improvements in measures of airway calibre, but it appears to have a higher risk of causing sore throat and when given at the same daily dose leads to increased hoarseness. There are concerns about adrenal suppression with Fluticasone given to children at doses greater than 400 mcg/day, but the randomised trials included in this review did not provide sufficient data to address this issue.

The Diskus: a review of its position among dry powder inhaler devices

The use of dry powder inhalers (DPIs) to administer treatments for respiratory diseases has increased significantly in recent years. There is now a wide range of DPIs available that vary considerably in design, required operational techniques, output characteristics and drug delivery across a range of inhalation patterns. Different patient populations may find individual types of DPI easier to use correctly than others and selecting the right DPI for particular patient requirements will improve compliance with therapy. For example, some DPIs offer a greater resistance against inspirational flow rate than others which affects the total emitted dose and also fine particle mass of the aerosol released. An individual patient may therefore receive different amounts of drug when inhaling from different DPIs. Therefore, it is important that the prescriber is fully aware of the characteristics of the different types of DPI, so that he or she can prescribe the device that is most appropriate to an individual patient's needs. This review explores the characteristics of currently available DPIs and evaluates their efficacy and patient acceptability. The differences in output characteristics, ease of use and patient preferences between available devices is shown to affect treatment efficacy and patient compliance with therapy. Changing the DPI prescribed to a patient to a cheaper or generic device may therefore adversely affect disease control and thereby increase the cost of treatment.

Can patients use all dry powder inhalers equally well?

If patients are unable to use their inhaler, drug delivery may be unsatisfactory and the patients may fail to benefit from the prescribed medication. It is important to consider whether patients can use all dry powder inhalers equally well. Changing a patient from a dry powder inhaler used well to one that the patient is unable to operate effectively could compromise asthma control. The many marketed dry powder inhalers reflect differences in design decisions that could affect lung deposition. Studies using different dry powder inhalers have confirmed that different lung deposition patterns are observed. Furthermore, there may be considerable individual variability in lung deposition. Differences in lung deposition patterns could have clinical effects. Studies may show similar clinical effectiveness with two inhalers, because most products are used at the plateau phase of the dose-response curve, although there may be differences in the adverse event profile. The ideal inhaler does not yet exist. Different dry powder inhalers show some but not all features of the ideal inhaler; hence, patients may prefer some aspects of one inhaler while favouring a different inhaler for other features. The individual balance of features will govern the overall preference for one inhaler over others. The method for operation of dry powder inhalers varies. Ease of use is seen as an important consideration when selecting an inhaler device, which should be evaluated in real-life studies using unselected patient populations. In conclusion, the evidence suggests that patients cannot use all dry powder inhalers equally well.

Idealhalers or realhalers? A comparison of Diskus and Turbuhaler

Medication for the treatment of asthma and chronic obstructive pulmonary disease should be given locally by inhalation. There is, however, no such thing as an ideal inhaler, or 'Idealhaler', which has all desired properties with no drawbacks. In this short review, we have compared the relative merits of the two most commonly used dry powder inhalers -- Turbuhaler and Diskus. Clinical effect is related to the amount of inhaled drug that reaches the lungs, and this in turn depends on the amount of fine particles generated at inhalation. Turbuhaler is more than twice as effective as Diskus at generating fine particles, and the higher lung deposition with Turbuhaler is accompanied by a lower variability in lung deposition. Compared with Diskus, the lung deposition with Turbuhaler is affected less by factors such as humidity.

Inhaled fluticasone versus inhaled beclomethasone or inhaled budesonide for chronic asthma in adults and children

BACKGROUND

Beclomethasone dipropionate (BDP) and budesonide (BUD) are commonly prescribed inhaled corticosteroids for the treatment of asthma. Fluticasone propionate (FP) is newer agent with greater potency in in-vitro assays.

OBJECTIVES

To compare the efficacy and safety of Fluticasone to Beclomethasone or Budesonide in the treatment of chronic asthma.

SEARCH STRATEGY

We searched the Cochrane Airways Group trial register (January 2004) and reference lists of articles. We contacted trialists and pharmaceutical companies for additional studies and searched abstracts of major respiratory society meetings (1997 to 2003).

SELECTION CRITERIA

Randomised trials in children and adults comparing Fluticasone to either Beclomethasone or Budesonide in the treatment of chronic asthma.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed articles for inclusion and methodological quality. One reviewer extracted data. Quantitative analyses were undertaken using RevMan analyses 1.0.1.

MAIN RESULTS

Fifty six studies (12, 119 participants) met the inclusion criteria. Methodological quality was variable. Dose ratio 1:2: FP produced a significantly greater FEV1 (0.14 litres, 95% Confidence Interval (CI) 0.06 to 0.22), morning PEF (11.10 L/min, 95%CI 3.12 to 19.09 L/min) and evening PEF (9.31 L/min, 95%CI 5.12 to 13.5 L/min). This applied to all drug doses, age groups, and delivery devices. No difference between FP and BDP/BUD were seen for trial withdrawals. Symptoms and rescue medication use were widely reported but few trials provided sufficient data for analysis. When given at half the dose of BDP/BUD, FP led to a greater likelihood of pharyngitis. There was no difference in the likelihood of oral candidiasis. Plasma cortisol and 24 hour urinary cortisol was measured frequently but data presentation was limited. Dose ratio 1:1: FP produced a statistically significant difference in am PEF (9.58 L/min (95% CI 5.20 to 13.97)), pm PEF (7.41 L/min (95% CI 2.61 to 12.22)), and FEV1 (0.09 L (0.02 to 0.17)). The effects on exacerbations were mixed. There was an increase in the incidence of hoarseness, but no significant difference in pharyngitis, candidiasis, or cough.

AUTHORS' CONCLUSIONS

Fluticasone given at half the daily dose of beclomethasone or budesonide leads to small improvements in measures of airway calibre, but it appears to have a higher risk of causing hoarseness when given at the same daily dose. Future studies should attempt to establish the relative efficacy of inhaled steroids delivered with CFC-free propellants.