Pulmonary function and adrenal gland suppression with incremental doses of aerosolized beclomethasone dipropionate in horses with recurrent airway obstruction.
OBJECTIVE
To evaluate clinical response, pulmonary function, and adrenal gland response to incremental doses of beclomethasone dipropionate in horses with recurrent airway obstruction.


METHODS
Crossover trial.


METHODS
8 horses with recurrent airway obstruction.


METHODS
Horses randomly assigned to 4 groups were treated twice daily via aerosol administration of placebo or 500, 1,000, or 1,500 micrograms of beclomethasone dipropionate in a crossover design with a 10-day minimum washout period. Subjective assessment of airway obstruction, serum cortisol concentration, and maximum change in pleural pressure during tidal breathing (delta Pplmax) were determined daily prior to morning drug administration, and delta Pplmax was reevaluated 15 minutes after morning drug administration. Pulmonary resistance and dynamic compliance were determined at baseline and approximately 12 hours after the final treatment.


RESULTS
An immediate treatment effect was not identified. Within 24 hours, delta Pplmax and airway obstruction were lower in horses receiving beclomethasone. Onset and magnitude of response was similar among the 3 beclomethasone dose regimens. Pulmonary resistance was improved only after administration of all 3 doses of beclomethasone, whereas dynamic compliance was improved after administration of 1,000 micrograms and 1,500 micrograms of beclomethasone. Reduction in serum cortisol concentration occurred with all 3 beclomethasone dose regimens; however, the magnitude of adrenal gland suppression was greater in horses receiving 1,000 or 1,500 micrograms of beclomethasone.


CONCLUSIONS
Low-dose (500 micrograms) beclomethasone administration caused similar, improvement in pulmonary function, compared with high-dose beclomethasone (1,000 and 1,500 micrograms), with the exception of dynamic compliance, and caused less suppression of endogenous cortisol production.
Rush
B R
BR
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan 66506-5606, USA.
Raub
E S
ES
Thomsen
M M
MM
Davis
E G
EG
Matson
C J
CJ
Hakala
J E
JE
D000287:Administration, Topical; D000311:Adrenal Glands / Q000187:drug effects* / Q000502:physiology; D000336:Aerosols; D000402:Airway Obstruction / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D001507:Beclomethasone / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D018592:Cross-Over Studies; D005260:Female; D006734:Horse Diseases / Q000188:drug therapy* / Q000503:physiopathology; D006736:Horses; D006854:Hydrocortisone / Q000097:blood; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008297:Male; D012129:Respiratory Function Tests / Q000662:veterinary
D000336:Aerosols; D000893:Anti-Inflammatory Agents; D001507:Beclomethasone; D006854:Hydrocortisone