Comparison of Sinus Deposition from an Aqueous Nasal Spray and Pressurised MDI in a Post-Endoscopic Sinus Surgery Nasal Replica.

BACKGROUND: Optimising intranasal distribution and retention of topical therapy is essential for effectively managing patients with chronic rhinosinusitis, including those that have had functional endoscopic sinus surgery (FESS). This study presents a new technique for quantifying in vitro experiments of fluticasone propionate deposition within the sinuses of a 3D-printed model from a post-FESS patient. METHODS: Circular filter papers were placed on the sinus surfaces of the model. Deposition of fluticasone on the filter paper was quantified using high-performance liquid chromatography (HPLC) assay-based techniques. The deposition patterns of two nasal drug delivery devices, an aqueous nasal spray (Flixonase) and metered dose inhaler (Flixotide), were compared. The effects of airflow (0 L/min vs. 12 L/min) and administration angle (30° vs. and 45°) were evaluated. RESULTS: Inhaled airflow made little difference to sinus deposition for either device. A 45° administration angle improved frontal sinus deposition with the nasal spray and both ethmoidal and sphenoidal deposition with the inhaler. The inhaler provided significantly better deposition within the ethmoid sinuses (8.5x) and within the maxillary sinuses (3.9x) compared with the nasal spray under the same conditions. CONCLUSION: In the post-FESS model analysed, the inhaler produced better sinus deposition overall compared with the nasal spray. The techniques described can be used and adapted for in vitro performance testing of different drug formulations and intranasal devices under different experimental conditions. They can also help validate computational fluid dynamics modelling and in vivo studies.

Using Filters to Estimate Regional Lung Deposition with Dry Powder Inhalers.

PURPOSE: To develop an in vitro method to rapidly evaluate regional lung doses delivered by pharmaceutical inhalers. Currently, cascade impactor measurements are used, but these are resource intensive and require significant post processing of in vitro data to arrive at regional deposition estimates. METHODS: We present a specialized filter apparatus that mimics tracheobronchial (TB) deposition of pharmaceutical aerosols emitted by commercially available dry powder inhalers (DPIs). The filter housing includes an electrostatic neutralizer to eliminate artificial electrostatic filtration effects. Regional deposition (tracheobronchial and alveolar) for four DPIs (Onbrez Breezhaler, Flovent Diskus, Pulmicort Turbuhaler, and Asmanex Twisthaler) was estimated using cascade impactor measurements and an in silico regional deposition model. These estimates were compared to direct measurements of regional deposition as provided by the TB filter mimic and an absolute filter placed downstream of the TB filter housing, representing the alveolar dose. RESULTS: The two methods were shown to provide similar estimates of extrathoracic, tracheobronchial, and alveolar deposition, as well as total recovery of active pharmaceutical ingredients. CONCLUSIONS: Because of its design, the TB filter apparatus makes it possible to estimate regional deposition with inhalers directly using variable inhalation profiles without any additional equipment or changes to the experimental configuration. This method may be useful to expedite development of both innovative and generic drug products as it provides regional respiratory tract deposition estimates using fewer resources than exisiting methods.

Drug Absorption Parameters Obtained Using the Isolated Perfused Rat Lung Model Are Predictive of Rat In Vivo Lung Absorption.

The ex vivo isolated perfused rat lung (IPL) model has been demonstrated to be a useful tool during drug development for studying pulmonary drug absorption. This study aims to investigate the potential use of IPL data to predict rat in vivo lung absorption. Absorption parameters determined from IPL data (ex vivo input parameters) in combination with intravenously determined pharmacokinetic data were used in a biopharmaceutics model to predict experimental rat in vivo plasma concentration-time profiles and lung amount after inhalation of five different inhalation compounds. The performance of simulations using ex vivo input parameters was compared with simulations using in vitro input parameters, to determine whether and to what extent predictability could be improved by using input parameters determined from the more complex ex vivo model. Simulations using ex vivo input parameters were within twofold average difference (AAFE < 2) from experimental in vivo data for all compounds except one. Furthermore, simulations using ex vivo input parameters performed significantly better than simulations using in vitro input parameters in predicting in vivo lung absorption. It could therefore be advantageous to base predictions of drug performance on IPL data rather than on in vitro data during drug development to increase mechanistic understanding of pulmonary drug absorption and to better understand how different substance properties and formulations might affect in vivo behavior of inhalation compounds.

Functional similarity of modified cascade impactor to deposit drug particles on cells.

Pulmonary drug delivery is a non-invasive and effective route for local or systemic drug administration. Despite several products in the market, the mechanism of drug absorption from the lungs is not well understood. An in vitro model for aerosol deposition and transport across epithelia that uses particle deposition may be a good predictor of and help understand in vivo drug disposition. The objective of this study was to examine the uptake of HFA fluticasone (Flovent HFA) particles at various stages of the Next Generation Impactor (NGI) by human Calu-3 cell line derived from human bronchial respiratory epithelial cell monolayer. Particles were directly deposited on Calu-3 cells incorporated onto stages 3, 5, and 7 of the NGI at the air-liquid interface (ALI). We modified the NGI apparatus to allow particle deposition directly on cells and determined the in vitro deposition characteristics using modified NGI. Particles of different size ranges showed different in vitro epithelial transport rates. This study highlights the need to develop in vitro test systems to determine the deposition of aerosol particles on cell monolayers by simultaneously considering aerodynamic properties.

Use of functional respiratory imaging to characterize the effect of inhalation profile and particle size on lung deposition of inhaled corticosteroid/long-acting ß2-agonists delivered via a pressurized metered-dose inhaler.

BACKGROUND: Functional respiratory imaging (FRI) uses three-dimensional models of human lungs and computational fluid dynamics to simulate functional changes within airways and predict the deposition of inhaled drugs. This study used FRI to model the effects of different patient inhalation and drug formulation factors on lung deposition of an inhaled corticosteroid/long-acting ß2-agonist (ICS/LABA) combination, administered by a pressurized metered-dose inhaler. METHODS: Three-dimensional models of the lungs of six patients with asthma (mean forced expiratory volume in 1 s, 83%), treated with an ICS/LABA, were included. FRI modelling was used to simulate (1) the effects on lung deposition of inhalation duration and particle size [fine particle fraction (FPF), proportion of particles <5 µm; and mass median aerodynamic diameter (MMAD), average size of inhalable particles]; (2) deposition of fluticasone propionate/formoterol (FP/FORM) 125/5 µg; and (3) how inhalation profiles and flow rates affected FP/FORM deposition. RESULTS: Total lung depositions (TLDs) following 1-, 3- and 5-s inhalations were 22.8%, 36.1% and 41.6% (metered dose), respectively, and central-to-peripheral deposition (C:P) ratios were 1.81, 0.86 and 0.61, respectively. TLD increased with increasing FPF, from ~8% at 10% FPF to ~36% at 40% FPF (metered dose); by contrast, MMAD had little effect on TLD, which was similar across MMADs (1.5-4.5 µm) at each FPF. FP/FORM deposited throughout central and peripheral airways with gradual (sinusoidal) and sharp (rapid) inhalations. TLD ranged from 35.8 to 44.0% (metered dose) for gradual and sharp inhalations at 30 and 60 L/min mean flow rates. CONCLUSIONS: These data provide important insights into the potential effects of inhalation characteristics (inhalation profile and duration) and aerosol formulation (FPF) on lung deposition of inhaled therapies. FRI thus represents a useful alternative to scintigraphy techniques. Future FRI studies will further our understanding of the deposition of inhaled drugs and help improve the management of asthma.

The Relationship Between the Permeability and the Performance of Carrier-Based Dry Powder Inhalation Mixtures: New Insights and Practical Guidance.

The permeability of a powder bed reflects its particle size distribution, shape, packing, porosity, cohesivity, and tensile strength in a manner relevant to powder fluidization. The relationship between the permeability and the performance of carrier-based dry powder inhalation (DPI) mixtures has, however, aroused controversy. The current study sought to gain new insights into the relationship and to explore its potential applications. We studied eight lactose materials as DPI carriers. The carriers covered a broad permeability range of 0.42-13.53 D and moreover differed in particle size distribution, particle shape, crystal form, and/or porosity. We evaluated the performance of inhalation mixtures of each of these carriers and fluticasone propionate after aerosolization from an Aerolizer®, a model turbulent-shear inhaler, at a flow rate of 60 L/min. Starting from the high permeability side, the inhalation mixture performance increased as the carrier permeability decreased until optimum performance was reached at permeability of ~ 3.2 D. Increased resistance to air flow strengthens aerodynamic dispersion forces. The inhalation mixture performance then decreased as the carrier permeability further decreased. Very high resistance to air flow restricts powder dispersion. The permeability accounted for effects of carrier size, shape, and macroporosity on the performance. We confirmed the relationship by analysis of two literature permeability-performance datasets, representing measurements that differ from ours in terms of carrier grades, drug, technique used to determine permeability, turbulent-shear inhaler, and/or aerosolization flow rate. Permeability provides useful information that can aid development of DPI mixtures for turbulent-shear inhalers. A practical guidance is provided.

Simultaneous analysis of glucocorticosteroid fluticasone propionate and its metabolite fluticasone propionate 17ß-carboxylic acid in human plasma by UPLC-MS/MS at sub pg/mL level.

A highly sensitive and rapid ultra performance liquid chromatography-tandem mass spectrometry method has been developed for the simultaneous determination of fluticasone propionate (FP) and its major metabolite, fluticasone propionate-17beta-carboxylic acid (FP 17ß-CA) in human plasma. The analytes and their deuterated internal standards, FP-d3 and FP 17ß-CA-d3 were extracted from 500µL plasma samples by solid phase extraction on Oasis MAX cartridges. The chromatographic analysis was performed on ACQUITY UPLC BEH C18 (50mm×2.1mm, 1.7µm) column using methanol-acetonitrile (50:50, v/v) and 2.0mM ammonium trifluroacetate (ATFA) (85:15, v/v) as the mobile phase. Following separation of the analytes, protonated precursor→product ion transitions (FP: m/z 501.1→293.2, FP17ß-CA: m/z 453.3→293.2, FP-d3: m/z 504.2→293.2, FP 17ß-CA-d3: m/z 456.3→293.2) were monitored on FP 17ß-CA a triple quadrupole mass spectrometer, operating in multiple reaction monitoring (MRM) and positive ionization mode. The calibration curves were established in the range of 0.5-100pg/mL with a correlation coefficient (r2)≥0.9992 for both the analytes. The intra-batch and inter-batch accuracy and precision varied from 95.5-103.4% and 0.74-5.06% across quality controls for both the analytes. The mean assay recoveries for FP and FP 17ß-CA were 84.2% and 93.5% respectively. The validated method was successfully applied to support a bioequivalence study of 200µg FP, administered using nasal spray formulation in 18 healthy Indian subjects. Reproducibility of the method was assessed by reanalysis of 98 incurred study samples.

Respiratory Tract Deposition of HFA-Beclomethasone and HFA-Fluticasone in Asthmatic Patients.

BACKGROUND: The asthmatic patient's respiratory tract deposition of HFA fluticasone (Flovent HFA(™)) has not been established. There is a known large particle size difference with another commercial inhaled HFA steroid (QVAR(™)). This study compared the 2D and 3D respiratory tract deposition of each inhaled steroid. METHODS: This study was an open label, crossover study in eight patients diagnosed with asthma. The regional respiratory and oropharyngeal deposition of the two steroids were compared and contrasted using planar and SPECT imaging following delivery of the (99m)Tc-radiolabeled drug in each product. The SPECT images were merged with computed tomography images to quantify regional deposition within the patients. RESULTS: Two-dimensional (2D) planar images indicated that 24% of the Flovent HFA dose and 55% of the QVAR dose deposited in the lungs. 2D oropharyngeal deposition indicated that 75% of the Flovent HFA dose was deposited in the oropharynx, while 42% of the QVAR dose deposited in the oropharynx. Three-dimensional (3D) SPECT data indicated that 22% of the Flovent HFA dose and 53% of the QVAR dose deposited in the lungs. 3D oropharyngeal and gut deposition indicated 78% of the Flovent HFA dose was deposited in the oropharynx, while 47% of the QVAR dose deposited in the oropharynx. The increased lung deposition and decreased oropharynx deposition for both 2D and 3D image data of QVAR were statistically different from Flovent HFA. CONCLUSIONS: QVAR exhibited a significant increase in lung delivery compared to Flovent HFA. Conversely, QVAR delivered a significantly lower dose to the oropharynx than Flovent HFA. The findings were presumed to be driven by the smaller particle size of QVAR (0.7 microns MMAD) compared with Flovent HFA (2.0 microns MMAD).

The reservoir effect of topical steroids in vitiliginous skin: A cross-sectional study.

BACKGROUND: Prolonged and frequent use of topical steroids may lead to decrease in efficacy as well as many local adverse effects. Stratum corneum has a unique property of reservoir effect. AIMS: To study the reservoir effect of topical steroids in a steroid-responsive condition which may enable a decrease in the dosing frequency of topical steroids. METHODS: A cross-sectional study design was used. Patients with at least three vitiliginous patches of more than 2 cm 2 present over the trunk or limbs were included. Exclusion criteria were topical or systemic corticosteroid use within the previous 4 weeks, antihistamine use within the previous 7 days, history of any allergy in the past and immunosuppression. Clobetasol propionate cream was applied on the first vitiliginous area (site A) and fluticasone propionate ointment was applied on the second vitiliginous area (site B). The third vitiliginous area, site C (control site) was left without applying any medication. Histamine-induced wheal suppression test was performed on each site, at the same time of the day, on every consecutive day following steroid application, until the values obtained at sites A and B approached those obtained at site C. SPSS software for Windows, version 16.0 was used for statistical analysis. The mean and standard deviation of the various studied parameters were calculated for various treatment groups and compared using analysis of variance (ANOVA) test. RESULTS: Forty patients were included in the study. The average wheal volumes and average erythema sizes at sites A and B were significantly smaller than the corresponding values at site C for up to 5 days after applying medication (P < 0.001). LIMITATIONS: The presence of a cutaneous reservoir of topical steroid was confirmed based on its suppressive effect on the wheal and flare response to histamine. It is not certain that the concentration that suppresses histamine-induced wheal and flare is sufficient for therapeutic efficacy in vitiligo. CONCLUSION: The reservoir effect of topical clobetasol propionate and fluticasone propionate persisted for 5 days in vitiliginous skin. Hence, it may be possible to reduce the frequency of topical steroid application in vitiligo.