Effects of lomefloxacin and sparfloxacin on human platelet aggregation.

Platelet aggregation is inhibited by high concentrations of most antibiotics. For this reason it is important to evaluate the effects of new antimicrobial agents on platelet aggregation. Lomefloxacin and sparfloxacin are new difluorinated quinolone antimicrobial agents. The aim of this work was to evaluate in vitro the effects of lomefloxacin and sparfloxacin on adenosinediphosphate (ADP) and collagen-induced human platelet aggregation. Our data showed that both antibiotics (lomefloxacin and sparfloxacin) at therapeutic doses did not inhibit in vitro human platelet aggregation. Lomefloxacin, only at the highest tested concentration (1 mg/ml), which is far higher than the clinically achievable one, significantly (P < 0.05) inhibited collagen-induced platelet aggregation. Sparfloxacin also caused inhibition of collagen and ADP-induced human platelet aggregation only at the highest tested concentration (0.01 mg/ml), which is higher than that reached in vivo. These findings suggest that therapeutic doses of lomefloxacin and sparfloxacin do not affect human platelet aggregation.