Cromolyn sodium: a review.

Cromolyn is a white crystalline powder which is poorly absorbed from the gastrointestinal tract. Its therapeutic value lies in its functions as an inhaled or topically applied agent. Cromolyn has been approved in the United States for asthma therapy since 1973. It was marketed at that time as a drug to reduce the corticosteroid requirements of severe asthmatics. It clearly did not live up to that claim. Initial enthusiasm for cromolyn was replaced by disillusionment. In the last few years, investigators have taken another look at cromolyn and have a renewed interest in it. Cromolyn's mechanisms of action remain only partially understood. It appears to block allergic mediator release from certain mast cells. It may also decrease bronchial hyperreactivity. The frequency of drug toxicity at customary dosages is extremely low. Adverse effects tend to be mild, short-lived and without sequelae. Currently, cromolyn is a first line therapy for mild to moderate asthma requiring chronic treatment. It is also of proven efficacy in the treatment of allergic rhinitis, allergic conjunctivitis and vernal keratoconjunctivitis.