Fenoterol: Pharmacology and Clinical Use

Fenoterol is a selective b2-adrenoceptor agonist that has been in clinical use for decades. It belongs to a family of compounds that have comparable pharmacological properties, such as terbutaline or salbutamol. The well-characterized, therapeutically useful pharmacological effects are bronchodilation and relaxation of the pregnant uterus. Therefore, fenoterol’s most important indications are bronchodilation (by inhalation, i.v., or p.o.) and tocolysis during premature labor (by i.v. infusion or p.o.). Fenoterol may also be used in states of acute hyperkalemia in patients with chronic renal failure, an indication that has not been thoroughly investigated. The side effects of fenoterol are typical for b2-adrenoceptor agonists, e.g., hypokalemia, cardiac acceleration, hypotension, and tremor. This review will summarize the current basic and clinical knowledge about fenoterol with a focus on the features that are most important therapeutically. It is surprising that human pharmacokinetics has received little attention. At the time of the development and initial marketing of fenoterol, it was technically difficult to detect small concentrations of the drug, particularly if it was administered by inhalation. Although this technical problem has been overcome, there are still no sensitive and enantioselective methods for detecting small amounts of fenoterol in the plasma to study its pharmacokinetics. Concerns over the safety of short-acting b2-adrenoceptor agonists, particularly fenoterol, have surfaced mainly in relation to their inhalation by asthmatics. This debate appears to be resolved after confusing and lengthy investigations and commentaries. The present review will attempt to report the current views on the use of short-acting b2adrenoceptor agonists in asthma, with a focus on fenoterol.