Adverse drug reactions related to the use of fluoroquinolone antimicrobials - An analysis of spontaneous reports and fluoroquinolone consumption data from three Italian regions

Objective: To analyse and compare with one another and with other antibacterial drugs the adverse drug reactions (ADRs) of the different fluoroquinolones currently used in Italy, spontaneously reported from doctors in three northern Italian regions. Methods: The data on fluoroquinolones and other antibacterials were obtained from the spontaneous reporting system database of Emilia Romagna, Lombardy and the Veneto, which are the principal contributors to the Italian spontaneous surveillance system. The fluoroquinolone ADRs with a causality assessment of certain, probable or possible (according to WHO criteria), reported between January 1999 and December 200 1, were selected and toxicity profiles of individual drugs were described and compared with one another. The reports were also correlated with sex and age of patients and with regional prescription data to estimate individual fluoroquinolone reporting rate of adverse events. Results: During the study period, 10 011 reports were received by the system (a mean annual reporting rate of approximately 185 per million inhabitants): 1920 referred to systemic antimicrobials, of which 432 (22.5%) involved fluoroquinolones. Pefloxacin was associated with the highest reporting rate (982 reports/daily defined dose/1000 inhabitants/day), followed by moxifloxacin (356), rufloxacin (221) and lomefloxacin (196). The most frequently reported reactions to fluoroquinolones involved the skin, but their percentage (25%) was significantly lower (p < 0.01) than those of other systemic antimicrobials (58.5%), whereas the percentages of reactions involving the central nervous (12.2 vs 3.6%), musculoskeletal (14.7 vs 0.3%) and psychiatric systems (9.3 vs 1.8%) were significantly higher (p < 0.01). We found some significant differences in the safety profiles of individual fluoroquinolones: ciprofloxacin was more frequently associated with skin reactions (p < 0.01), levofloxacin and pefloxacin with musculoskeletal (p < 0.01), and rufloxacin with psychiatric disorders (p < 0.05). Levofloxacin was the fluoroquinolone associated with the highest rate of serious tendon disorders; phototoxic reactions were more frequent with lomefloxacin, and toxic epidermal necrolysis and Stevens-Johnson syndrome were seen only with ciprofloxacin. Conclusions: The differences in the safety profiles should be taken into account when prescribing a fluoroquinolone to individual patients.