Subsensitivity of beta responses on terbutaline therapy.

drug when nearing exhaustion which would lead to a decline in the response to the drug. Most likely the development of drug tolerance to beta, agonists involves more than one mechanism. The workshop was fruitful in amunulating further evidence that drug tolerance to beta, agonists does develop. It is clear that further studies are needed to define the clinical sigdicance of drug tolerance, the clinical sigr&ance of cross-tolerance, and the mechanism or mechanisms responsible.