Bronchospasm, a common problem, whether related to asthma or chronic obstructive lung disease, can be treated with bronchodilators. These include pri-marily phosphodiesterase inhibitors and beta-adrenergic drugs.
Two phosphodiesterase inhibitors, aminophylline (Phyllocontin®; Tru-phylline®) and theophylline (Theo-Dur® and many others), cousins to caffeine, can be infused intravenously. Patients not previously exposed to the drugs receive a loading dose and then a continuous infusion aiming for serum concentrations associated with bronchodilation. Serum levels in excess of 25 mcg/mL are asso-ciated with seizures and arrhythmias.
Among the β2-adrenergic bronchodilators, albuterol (Ventolin® and many others) and terbutaline (Brethaire®) find common use for inhalation. Albuterol has a longer duration of action (up to 6 hours) than terbutaline (up to 3 hours). Even though they are beta2 agonists, some patients develop beta1 effects, such as tachycardia and arrhythmias. Therefore, caution should be exercised in admin-istering them to cardiac patients in whom tachycardia would be dangerous.