Patients w/ thyrotoxicosis; cardiac arrhythmias, coronary insufficiency, HTN, ischemic heart disease, DM, hyperthyroidism, ketoacidosis, pheochromocytoma, sensitivity to sympathomimetics. Concomitant use w/ antihypertensives; anesth cyclopropane or halothane; cardiac glycosides, quinidine or TCAs. Should not be prescribed to patients under treatment w/ β-blockers. Pregnancy (1st trimester).