NEBULIZED LIDOCAINE: AN OPTION FOR SEVERE ASTHMA
may help reduce glucocorticoid dependence in patients with asthma. In vitro
work suggests that lidocaine may limit evoked bronchoconstriction by boosting
the steroids effects and independently opposing the ability of cytokines
to promote eosinophil survival.
Lidocaine should be
a first-choice agent for any asthma patient who has maxed out on corticosteroids,
Loren W. Hunt, MD, told RESPIRATORY REVIEWS.
Despite glucocorticoids proven efficacy in treating asthma, significant side effects make it important that their use be minimized. Dr. Hunt and colleagues from the Mayo Medical School in Rochester, Minnesota, tested the ability of nebulized lidocaine to allow reduction or elimination of oral glucocorticoids in steroid-dependent asthma patients with evidence of hypercortisolism.
Two to four times daily, 47 patients who required oral glucocorticoids for adequate asthma control received 2.5 mL of 2% or 4% lidocaine via a nebulizer. Within one to two weeks, symptoms improved, said Dr. Hunt, an Assistant Professor of Medicine at Mayo at the time of the study, and now in private practice. At that point, we were able to start withdrawing glucocorticoids.
Of the 47 patients, 40 (85%) were able to reduce their glucocorticoid dosages
significantly. And 31 (66%) could stop systemic glucocorticoid use altogether. Nebulized lidocaine administration also halved the rate of hospitalization for asthma among study patients.
Lidocaine definitely blocks the ability of cytokines, such as interleukin 5, to prolong survival of eosinophils in vitro, said Dr. Hunt, but how it interferes with eosinophil activation has yet to be worked out. Theres no receptor for it; rather, it diffuses in through the membrane.
Aside from the independent actions of lidocaine, it really enhances the effects of glucocorticoids, Dr. Hunt pointed out. There clearly is synergy in vitrothe degree of inhibition of eosinophil activation is greater than the sum of each drugs effect, possibly providing further explanation of how lidocaine reduces patients glucocorticoid requirements.
AVOID MEALTIMES, HIGH DOSES
The side-effect profile is minimal for nebulized lidocaine, remarked Dr. Hunt, who recommends that patients avoid eating or drinking one hour before and two hours after treatment with the anesthetic, which may cause numbness of the mouth and throat. Throat or gastrointestinal irritation prompted two patients to withdraw from the study, he noted.
Ironically, lidocaine may initially irritate airways and cause bronchoconstriction in some individuals. About 10% of people with asthma will get reduced airflow about 10 minutes into treatment with lidocaine. That seems to be related to the degree of
hyperresponsiveness, or how symptomatic their asthma is at that time. Therefore, Dr. Hunt cautioned, Its very necessary to do the first treatment under observation, and if youre concerned about hyperresponsiveness, give it at a lower dosageif you go down to 2% lidocaine, you get very little airway closure.
Other researchers have reported
that combining albuterol with nebulized lidocaine may also help prevent this initial
bronchoconstriction. The effects of the two drugs may be additive, suggesting
benefits with combined therapy, said Dr. Hunt.
Mimi Zucker, PhD
1. Pongdee T, Frigas E, Hunt LW. Nebulized lidocaine is the drug of choice for
severe steroid-dependent asthma. Presented at: American College of Allergy, Asthma
& Immunology 2001 Annual Meeting; November 18, 2001; Orlando, Fla. Abstract
2. Groeben H, Silvanus MT, Beste M, Peters J. Combined lidocaine and salbutamol
inhalation for airway anesthesia markedly protects against reflex bronchoconstriction.