Characterization of histamine release induced by fluoroquinolone antibacterial agents in-vivo and in-vitro

Characterization of histamine release induced by fluoroquinolone antibacter ial agents, levofloxacin and ciprofloxacin, was investigated in-vivo and in -vitro. Intravenous injection of levofloxacin and ciprofloxacin at 1-10 mg kg(-1) p roduced dose-related elevations in plasma histamine level in anaesthetized dogs. In contrast, levofloxacin was devoid of plasma histamine increment in anaesthetized rats at 100 mg kg(-1), whereas ciprofloxacin at the same dos e caused endogenous histamine release. Levofloxacin and ciprofloxacin induc ed non-cytotoxic secretion of histamine from all mast cells tested in a con centration-dependent manner, whereas rat skin and peritoneal mast cells wer e thirty- to one-hundred-times less sensitive to the effect of fluoroquinol ones as compared with the canine skin mast cells. These results suggest that the functional heterogeneity of mast cells from different species in histamine releasing activity of fluoroquinolones may e xist, and that mast cells from the dog appear to be particularly sensitive to the effect of the fluoroquinolones.