Aerosolized chlorpheniramine provides relief in exercise-induced asthma
INDIA: The use of aerosolized chlorpheniramine provides relief in exercise-induced asthma (EIB) by causing bronchodilation during the resting period, according to a recent study in the Journal of the Association of Physicians of India. Chlorpheniramine causes bronchodilation by acting on the circulating or tissue histamine in asthmatics contributing to an increase in bronchomotor tone. But Chlorpheniramine provides only incomplete inhibition of EIA suggesting that there may be other associated mediators release for EIA pathogenesis.
Exercise-induced asthma (EIB) is an acute, reversible, usually self-limiting airways obstruction that may occur after exercise in asthma patients. The mechanism involved behind this is the increase in histamine and its metabolites in circulation after exercise. This leads to bronchoconstriction via histamine receptors in bronchi.
Chlorpheniramine Maleate is a potent, less sedative antihistaminic drug that acts by inhibiting histamine release from mast cells. It is also said to have anticholinergic properties. The administration of a drug via aerosol route has the advantages of fewer side effects, a faster onset of action and greater protection against EIB with respect to the function of small airways.
Jagdeep Chugh, Sr. Consultant, Fortis Hospital, Shalimar Bagh, Delhi, and colleagues conducted the study to evaluate the effect of Chlorpheniramine Maleate aerosol inhalation on flow volumes and gas exchange.
The study included 25 patients of stabilized bronchial asthma (18 to 44 years). They had a history of EIA attending Allergy OPD, Medical OPD or Chest clinic. They were studied for 3 days in a week at the same time of the day.
Baseline spirometry was performed to know test parameters i.e. FEV1, PEFR, and FEF50%. The researchers carried out Gas exchange study during rest including minute ventilation (VE), oxygen consumption (VO2), Carbon dioxide produced per minute (VCO2), Respiratory quotient (R). Patients were asked to perform exercise on a bicycle ergometer. VE, VO2, VCO2, and R were recorded during exercise for every 30 seconds. FEV1, PEFR, and FEF50% were recorded immediately after and 5 min after completion of the exercise. On day 2, the same procedure was repeated with saline nebulization before the exercise. On day 3, aerosolized Chlorpheniramine Maleate was used instead of saline for nebulization. The values obtained were tabulated and analyzed.
Key findings of the study include:
- After exercise FEV1, PEFR, FEF50% decreased on all three days, but the fall in these parameters was less on Day III (prior nebulization with Chlorpheniramine maleate) compared to previous days.
- There was significant increase in FEV1, PEFR and FEF50% (P<0.01, 0.05 and 0.05 respectively) which was seen 30 mins after inhalation of Chlorpheniramine maleate aerosol compared to the placebo.
- Resting and exercise values of Minute Ventilation (VE), oxygen uptake (VO2) carbon dioxide expired, on all the three days were comparable and statistically not significant by the end of the exercise.
- On day 2 and 3, 'R' as compared to that of day1 was slightly significant during rest and initial minutes of exercise but became insignificant after that till the end of exercise.
"This study shows that Chlorpheniramine causes bronchodilation during the resting period by acting on the circulating or tissue histamine in asthmatics which contributes to an increase in resting bronchomotor tone. As there is incomplete inhibition of EIA by Chlorpheniramine, there may be some other associated mediator release for the pathogenesis of EIA," concluded the authors.
The study, "The Effect of Aerosolized Chlorpheniramine Maleate on Exercise Induced Bronchospasm and Gas Exchange in Asthmatics," is published in the journal JAPI.
