Safety profile of the fluoroquinolones: analysis of adverse drug reactions in relation to prescription data using four regional pharmacovigilance databases in Italy

BACKGROUND: Fluoroquinolones are widely used both in primary care and in hospital settings. Since the last comparison performed in Italy on the safety profiles of different fluoroquinolones, a new molecule, prulifloxacin, has been introduced into the market and several warnings concerning this class of drugs have been released. The aim of this study was to reassess the safety profiles of fluoroquinolones using the database of the Italian Interregional Group of Pharmacovigilance (IGP) and the administrative data of fluoroquinolone prescriptions. METHODS: All adverse drug reactions (ADRs) reported in four Italian regions (Lombardy, Veneto, Emilia Romagna and Tuscany) were retrieved from the IGP database. Consumption data (defined daily dose [DDD]/1000 inhabitants/day) were used as denominators. Both single reports and all ADRs (classified by System Organ Classes and MedDRA Preferred Term [PT]) due to fluoroquinolones were considered as numerators of each analysis, comparing two periods (2005 vs 2006). All fluoroquinolones with at least ten reports per year were included in the analysis. RESULTS: On the basis of 272 reports (532 single ADRs or PTs), patients did not show any statistically significant differences between 2005 and 2006 in terms of sex, age and number of concurrent medications. After adjustment for drug consumption, moxifloxacin showed the highest reporting rate (84.6 reports/DDD/1000 inhabitants/day; 15.4 serious reports/DDD/1000 inhabitants/day) followed by prulifloxacin (72.2; 22.2 serious) and levofloxacin (55.3; 30.6 serious) in 2005. An increment of ADR/report rates was observed over the 2 years for all fluoroquinolones except prulifloxacin, which had the lowest ADR reporting rate in 2006 (25.0; 12.5 serious). In 2006, the rate of serious ADRs associated with prulifloxacin was lower than with ciprofloxacin, while in 2005 serious events were almost equal for both compounds (55.6 vs 47.6 serious ADRs/DDD/1000 inhabitants/day). Ciprofloxacin showed the highest proportion of cutaneous PTs (e.g. rash, exanthema). Tendinopathies were mainly due to levofloxacin. CONCLUSIONS: These data suggest that different fluoroquinolones are characterized by different rates and types of ADRs. Among them, prulifloxacin was associated with more ADRs than other fluoroquinolones in 2005 but with fewer ADRs in 2006, when its consumption increased. Although these findings may represent an encouraging perspective towards a more appropriate use of fluoroquinolones because of their individual safety profiles, further pharmacoepidemiological studies must be performed to substantiate these results.