Enantiomer-specific effects of albuterol on airway inflammation in healthy and asthmatic cats.
BACKGROUND
Racemic (R,S)-albuterol is a 1:1 mixture of an R-enantiomer which has bronchodilatory and anti-inflammatory effects, and an S-enantiomer which is associated with increased airway hyperreactivity and proinflammatory effects. Proinflammatory effects of regularly inhalated and S-albuterol have not been studied in a whole-animal model. We hypothesized that regular administration of R,S-albuterol or S-albuterol, but not R-albuterol, would induce airway inflammation in healthy and asthmatic cats.


METHODS
Six healthy and 5 experimentally asthmatic cats were randomized to receive inhaled R,S-albuterol, S-albuterol, R-albuterol, or placebo (saline) twice daily for 2 weeks, followed by a 6-week washout before crossover to the next treatment. Bronchoalveolar lavage fluid was collected for cell counts and cytokine analysis prior to and at the end of each 2-week treatment.


RESULTS
Healthy and asthmatic cats receiving R,S- and S-albuterol had higher total lavage cell numbers (p = 0.04 and p = 0.02, respectively) than those receiving R-albuterol and placebo. The number of lavage eosinophils and the TNF-alpha bioactivity was higher in asthmatic cats receiving R,S- and S-albuterol compared with those receiving the other treatments (p = 0.03 and p = 0.004, respectively). In healthy cats, the number of lavage neutrophils was higher when they received R,S- and S-albuterol compared with other treatments (p = 0.04).


CONCLUSIONS
Airway inflammation is induced in both healthy and asthmatic cats with regular inhalation of racemic and S-albuterol, but not with R-albuterol.
Reinero
Carol R
CR
Department of Veterinary Medicine and Surgery, School of Veterinary Medicine, University of Missouri, 900 East Campus Drive, Columbia, MO 65211, USA. reineroc@missouri.edu
Delgado
Cherlene
C
Spinka
Christine
C
DeClue
Amy E
AE
Dhand
Rajiv
R