Levofloxacin was introduced to the USA in 1997 with no drug-related AE reported at a rate higher than 1.3%. This has remained virtually unchanged with only minimal adjustments to the FDA-approved label. Dr Kahn updated the safety data of levofloxacin reporting results from four recently completed clinical trials. The first investigated 500 milligrams levofloxacin once daily versus intravenous ceftriaxone/erythromycin changing to amoxicillin-clavulanic acid and clarithromycin in seriously ill community-acquired pneumonia patients. Levofloxacin achieved a superior clinical success rate of 89% versus 84% for the comparators, and microbiological eradication of 85% versus 75% for the comparator group. In addition, in terms of drug-related AEs, levofloxacin was less likely to cause any type of adverse event, apart from insomnia.

Intravenous azithromycin plus ceftriaxone versus 500 milligrams of levofloxacin once daily in hospitalised CAP patients again proved levofloxacin to be better with a clinical success rate of 94% compared to 92% for the comparator. The ADR rate for all body systems was 5.3% for levofloxacin compared to the much higher 9.3% for the alternative agents. Diarrhoea and vein disorders, seen in the comparator arm, were not seen with levofloxacin, and dizziness was noted in only 0.9%.

A large surveillance trial, including some patients with drug-resistant Streptococcus pneumoniae, revealed a clinical success rate of 95.3% and a microbiological eradication rate of 94.7% for 500 milligrams of levofloxacin once daily. The most common drug-related AEs were very low, all below 1%.

A trial using 750 milligrams of levofloxacin once daily in skin and soft tissue infections resulted in a clinical success rate of 84% compared to 80% for the comparator agents ticarcillin plus amoxicillin-clavulanic acid. The total adverse event rate, regardless of drug or disease attribution, was much lower for levofloxacin than the comparator group. Both agents had a drug-related adverse event rate of 5% showing that, even at a higher dose, levofloxacin maintains excellent tolerability.

Spontaneous AEs reported regardless of attribution also confirmed the safety of levofloxacin. Data derived from more than 15 million prescriptions reported tendon rupture occurring at a rate of less than 4 per million prescriptions, taste perversion in less than 3 per million, convulsions in only 2 per million, and photosensitivity, hepatic failure and QT prolongation in less than 1 per million prescriptions.The safety profile for levofloxacin remains as excellent as it was in 1997, with a reassuring lack of rare or unexpected adverse events in the 130 million prescriptions issued.