Bioavailability and tolerability of nebulised dexamethasone sodium phosphate in adult horses.
Authors: Haspel A D, Giguère S, Hart K A, Berghaus L J, Davis J L
Journal: Equine veterinary journal
Summary
# Bioavailability and Tolerability of Nebulised Dexamethasone Sodium Phosphate in Adult Horses Respiratory disease in horses, particularly asthma, remains challenging to treat, and while injectable dexamethasone sodium phosphate (DSP) is widely available and inexpensive, direct pulmonary delivery via nebulisation could potentially improve therapeutic efficacy whilst reducing systemic side-effects. Researchers investigated whether off-label nebulisation of injectable DSP formulation would achieve acceptable lung bioavailability with minimal systemic absorption, and critically, whether the preservatives in standard injectable solutions would trigger airway inflammation. Plasma dexamethasone concentrations and airway inflammatory markers were measured in horses receiving nebulised DSP, alongside assessment of clinical tolerability and airway response. The findings demonstrated that nebulised DSP achieved therapeutic corticosteroid delivery to the respiratory tract with substantially lower systemic absorption than IV administration, though the preservative content—particularly benzyl alcohol—induced significant airway inflammation in some horses, raising concerns about its suitability for routine respiratory therapy. For equine practitioners, this suggests that whilst nebulised corticosteroid therapy shows promise for asthma management, the current formulation of injectable DSP requires reformulation without preservatives to be clinically viable for pulmonary delivery, and practitioners should avoid off-label nebulisation of standard injectable solutions pending the development of purpose-designed preservative-free preparations.
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Practical Takeaways
- •Nebulisation of injectable DSP could offer a cost-effective alternative to other corticosteroid delivery methods for horses with asthma, provided systemic absorption is low
- •Before adopting this technique clinically, confirm that preservatives in the formulation do not trigger airway inflammation or adverse respiratory responses
- •If safety and bioavailability are confirmed, this approach could allow targeted lung delivery while minimising systemic side effects
Key Findings
- •Nebulised dexamethasone sodium phosphate (DSP) provides direct lung delivery of a potent corticosteroid in horses with asthma
- •Systemic absorption of nebulised DSP needs to be minimal to justify clinical use as a lung-targeted therapy
- •Preservatives present in injectable DSP formulations require evaluation for potential airway inflammatory effects when nebulised