Actions of diethylcarbamazine in experimental anaphylaxis.

Diethylcarbamazine citrate (DEC) is an anthelmintic drug which has been used recently, with varying results, in the treatment of bronchial asthma. We have examined the pharmacological activity of this drug in several in vivo and in vitro models of experimental anaphylaxis. DEC at doses of 25 and 50 mg per kg given intraperitoneally significantly reduced the mortality rate in sensitized guinea pigs during protracted shock phase but did not modify the time for the appearance of dyspnoea when antigen (egg albumin) was administered as aerosol. Nor did DEC at therapeutic doses inhibit the degranulation and histamine release from rat isolated peritoneal mast cells induced by phospholipase A, compound 48/80, and antigen respectively. It has been suggested that one possible explanation for the apparent effectiveness of DEC in asthma is its ability to antagonize prostaglandin F2 alpha. Our results using in vivo and in vitro models of bronchoconstriction in guinea pigs do not support this hypothesis to explain the inhibition of protacted shock by DEC.