Serious ADRs have been reported for a number of fluoroquinolones. These include enoxacin, temafloxacin and sparfloxacin. The most recent safety-related issues have involved trovafloxacin and grepafloxacin. The time between the launch of these agents until occurrence of these safety issues ranged from 6 months to two years. With this in mind, Dr Yagawa reported results confirming the safety of levofloxacin based on a six-year post-marketing surveillance study in Japan.

Phototoxicity is reported as a class effect associated with new quinolones, but this appears to be a much reduced problem with levofloxacin. Only 45 cases of levofloxacin-induced phototoxicity were reported. Assuming an event-reporting rate of 10%, the incidence for levofloxacin is 1 in 200,000 compared to 1 in 189 for sparfloxacin.

While myocardial conduction disturbance is often cited as a class effect for the new quinolones, datum is available showing levofloxacin has no effect on myocardial conduction in vitro. PMS data shows just one case of QT prolongation or torsade de pointes has been reported with levofloxacin in Japan, and only eight worldwide. Thus, levofloxacin appears virtually free of myocardial toxicity.

Trovafloxacin is estimated to cause serious hepatic reactions at a rate of 1 in 1,800 patients. However, for levofloxacin, the total number of cases in Japan was 87, yielding a very low estimated incidence of 1 in 100,000. These results are confirmed by the worldwide incidence rate of 1 per 109,000 patients.

Ofloxacin, the parent compound of levofloxacin, has been used for a long time, and is one of the safest fluoroquinolones with an overall ADR rate of just 2.6%.In a prospective study, levofloxacin had an even lower ADR rate, showing that it is extremely safe.Thus, clinicians can continue to use levofloxacin with confidence in its excellent safety record.