Anti-inflammatory effects of two new methyl and morpholine derivatives of diphenhydramine on rats

Diphenhydramines are one of the first-generation histamine H-1-receptor antagonists of the ethanolamine class that demonstrate many pharmacological properties including anti-inflammatory effects. In this research, bromo (II) and two new tolyl derivatives of I, (Di [p-tolyl] [dimethylaminoethoxy] methane, III) and (Di [p-tolyl] [2-morpholinoethoxy] methane, IV) were synthesized. Their acute and chronic anti-inflammatory activities were evaluated with the formalin and histamine-induced rat paw edema. The vascular permeability in formalin and histamine-induced paw edema, in xylene-induced ear edema, and in peritonitis after acetic acid application into peritoneal cavity were also measured and compared to II. Cotton pellet-induced granuloma model was selected for inducing chronic inflammations in rats. The newly synthesized analogs of diphenhydramine seemed effective to decrease acute inflammations. It was concluded that the prominent anti-phlogistic effects of the new drugs could be related to its reduction vascular permeability mechanism(s) or to its antagonistic effects on H-1 histamine receptors.