Bronchodilators are central in the treatment of of airways disorders. They are the mainstay of the current management of chronic
obstructive pulmonary disease (
COPD) and are critical in the symptomatic management of
asthma, although controversies around the use of these drugs remain.
Bronchodilators work through their direct relaxation effect on airway smooth muscle cells. at present, three major classes of
bronchodilators, β(2)-adrenoceptor (AR)
agonists, muscarinic receptor antagonists, and
xanthines are available and can be used individually or in combination. The use of the inhaled route is currently preferred to minimize systemic effects. Fast- and short-acting agents are best used for rescue of symptoms, whereas long-acting agents are best used for maintenance
therapy. It has proven difficult to discover novel classes of
bronchodilator drugs, although potential new targets are emerging. Consequently, the logical approach has been to improve the existing
bronchodilators, although several novel broncholytic classes are under development. An important step in simplifying
asthma and
COPD management and improving adherence with prescribed
therapy is to reduce the dose frequency to the minimum necessary to maintain disease control. Therefore, the incorporation of once-daily dose administration is an important strategy to improve adherence. Several once-daily β(2)-AR agonists or ultra-long-acting β(2)-AR-agonists (LABAs), such as
indacaterol,
olodaterol, and
vilanterol, are already in the market or under development for the treatment of
COPD and
asthma, but current recommendations suggest the use of LABAs only in combination with an inhaled
corticosteroid. In addition, some new potentially long-acting
antimuscarinic agents, such as
glycopyrronium bromide (NVA-237),
aclidinium bromide, and
umeclidinium bromide (
GSK573719), are under development, as well as combinations of several classes of long-acting
bronchodilator drugs, in an attempt to simplify treatment regimens as much as possible. This review will describe the pharmacology and
therapeutics of old, new, and emerging classes of
bronchodilator.