Montelukast (
Singulair) is an
antiasthmatic agent that has the chemical structure of a
quinoline.
Montelukast has a high affinity for the
CysLT1 receptor and a potency that is not influenced by human
serum protein.
Montelukast antagonizes contractions of guinea-pig trachea induced by
LTD4 in a competitive manner. Intravenous
montelukast inhibited bronchoconstriction induced by
LTD4 in guinea pigs. Oral
montelukast inhibited increased airway resistance induced by
antigen in squirrel monkeys.
Montelukast also inhibited both inflammatory and immunologic responses induced by either
LTD4 or
antigen in guinea pigs and rats. Plasma concentrations of
montelukast after
oral administration of 10 mg in humans were shown to be over the effective level for at least 24 h. These lines of evidence support the effectiveness of a regimen of 10 mg/day for asthmatic symptoms in humans. In a number of clinical experiments,
montelukast not only improved asthmatic symptoms and respiratory indices, but also inhibited airway
inflammation and exercise-induced bronchoconstriction. These effects persisted during extended treatment.
Montelukast produced an additive effect to basic
therapy with an inhaled
steroid. There were no differences in the incidence and magnitude of adverse effects between
montelukast and placebo groups in clinical experiments.
Montelukast is expected to serve as a first line of asthmatic
therapy because of its consistent efficacy and good safety profile and it is associated with good compliance in patients because of its simple regimen of one 10 mg
tablet/day.