Aerosol deposition in equine lungs following ultrasonic nebulisation versus jet aerosol delivery system

Abstract

Summary Therapeutic aerosols play an increasing role in the treatment of equine respiratory disorders. This route of delivery permits concentration of significant amounts of drugs at the site of action without unwanted high systemic concentration and resultant side effects. The efficiency of such a topical therapy depends on the quantity of inhaled drugs deposited in the lungs and, for some drugs, on the proportion retained in specific parts of the lungs. The objective of this study was to define and to compare quantitative (dose deposited) and qualitative (regional distribution) deposition of an aerosol in the equine lungs, using either an ultrasonic nebuliser (UN) currently used in human medicine or a high pressure jet nebuliser (JN) especially developed for the equine species. This comparison was possible owing to gamma‐scintigraphy, a noninvasive technique ideally suited to give information about both total and regional deposition of inhaled drugs in the respiratory tract. The quantitative study did not point out any difference between the 2 systems concerning the activity released from the nebuliser proportionally to the initial loaded dose (mean ± s.d. 45.95 ± 4.93% for the UN vs. 46.47 ± 8.49% for the JN). By contrast, the percentage of the dose released reaching the lungs was significantly lower with the UN compared to the JN (5.09 ± 0.66% vs. 7.35 ± 1.96 %). The qualitative analysis did not show any significant difference in size of aerosol deposition image between the 2 nebulisers. However peripheral deposition was significantly higher with JN compared to UN. In conclusion, both nebulisers may be used for aerosol therapy in the equine species. The ultrasonic and pneumatic nebulisation achieved drug deposition in the peripheral part of the lungs (i.e. small airways and lung parenchyma).

Concentrations of gentamicin in serum and bronchial lavage fluid after intravenous and aerosol administration of gentamicin to horses

“…44 High concentrations of aminoglycosides result in more rapid and extensive bacterial killing than low concentrations and prolong the duration of the postantibiotic effect. 17,[45][46][47][48] As a result of the inability of aerosol administration to deliver medication to areas of the lungs that are not ventilated, the administration of antimicrobials by inhalation alone is not appropriate when substantial consolidation or parenchymal involvement is evident, but it may be of benefit as an adjunct to oral or parenteral administration. 44 Administration of medications by aerosolization and inhalation has several limitations, including the inability to deliver medication to areas of the lungs that are not ventilated, potential inactivation of the medication, time-consuming administration, potential for pulmonary tissue irritation or injury, atmospheric contamination with aerosolized medication, and potential contamination of the antimicrobial solution with microorganisms.…”

Use of the impulse oscillometry system for testing pulmonary function during methacholine bronchoprovocation in horses

“…15 Pulmonary function test measurements were started 30 seconds after the end of nebulization and recorded for 3 minutes. The sequence of challenges was sterile isotonic saline (0.9% NaCl) solution, followed by methacholine chloride m in saline solution at successive increasing concentrations (0.01 mg/mL, 0.1 mg/mL, 1 mg/mL, 2 mg/mL, and 3 mg/mL).…”

Factors affecting the efficiency of aerosolized salbutamol delivery via a metered dose inhaler and equine spacer device

“…The limited data relating to drug delivery via an equine‐specific spacer are largely derived from in vivo scintigraphic studies which revealed relatively poor and markedly varied aerosol delivery to the peripheral airways (Votion et al ., , ; Rush et al ., ). Due to the lack of published in vitro studies on MDI‐generated aerosol characteristics using equine spacers, this study was designed to measure the efficiency of delivery and particle size distribution of an MDI‐generated salbutamol aerosol delivered via an equine spacer device.…”