Subsensitivity to the bronchodilator action of albuterol produced by chronic administration.

Evidence of bronchodilator subsensitivity was sought in studies using the specific beta2 adrenergic agonist, albuterol. After a period of 1 or 2 weeks off all oral sympathomimetic agents, the mean response of the patients to the first dose of albuterol was consistently greater than the response after a period during which the drug had been administered regularly. Maximal decrease in response occurred after 2 weeks' of treatment, and there was no further decrease after prolonged treatment with the same dose of albuterol for periods as long as 1 year.