Cardiovascular Effects of Intramuscular or Inhaled Terbutaline in Asthmatics

Abstract
Stable asthmatics (8) were at random given placebo, 0.125 mg, 0.25 mg, 0.5 mg and 1 mg terbutaline i.m. or 2.5 mg as inhalation. Systolic time intervals, echocardiographics parameters and peak expiratory flow (PEF) were measured. Maximal circulatory and respiratory response was obtained after 0.5 mg and 0.25 mg, respectively. The circulatory effect of 2.5 mg inhalated terbulatine equalled 0.125 mg given i.m., while this dosage elicited maximal bronchodilator effect. Nebulized terbutaline has only a minimal circulatory effect, and even the i.m. dosages were without dramatic circulatory side effects. [The circulatory effect of terbutaline is at moderate dosages mainly due to .beta.2-stimulation.].