Modification of antihistaminic activity of cetirizine by nimesulide.

OBJECTIVE To study the effect of nimesulide (4-nitro-2-phenoxymethane sulfonanilide) a non-steroidal anti-inflammatory drug, on antihistaminic activity of cetirizine. METHOD A randomized, double blind, cross over study was conducted in ten healthy male volunteers. Wheal and flare responses to histamine were measured by performing intradermal injection of histamine (2 micrograms base) diluted in 100 microliters volume of saline on the volar surface of forearm, on four occasions (0, 2, 4, and 6 hrs. post-dosing). Each volunteer was randomized to receive either treatment A (cetirizine 10 mg + placebo) or treatment B (cetirizine 100 mg + nimesulide 100 mg), with one week wash out period in between each administration. Wheal and flare responses were measured ten minutes after each histamine injection. RESULTS Both cetirizine 10 mg alone and cetirizine 10 mg + nimesulide 100 mg, decreased wheal and flare responses significantly at 2 hrs. and this continued till 6 hrs. post-dosing. This decrease was highly significant when cetirizine was given along with nimesulide. CONCLUSION The results suggest a synergistic effect exhibited by the combined use of cetirizine with nimesulide.