Can fluoroquinolones be considered once-daily therapy?

Fluoroquinolone antimicrobial agents inhibit most Enterobacteriaceae at extremely low concentrations, less than or equal to 0.5 microgram/mL. The half-lives of the agents range from 4 to 18 hours. Most of the available fluoroquinolones can be administered once daily to treat urinary tract and diarrheal infections. Newer agents with long half-lives that inhibit gram positive organisms at lower concentrations than the older fluoroquinolones, less than or equal to 1 microgram/mL, and have a long post-antibiotic effect have the potential to be used once daily as treatment of respiratory, skin-structure and selected bone infections as well. Careful clinical studies are needed to establish the efficacy of once daily use of fluoroquinolones, to determine that clinical efficacy is equivalent to multiple doses, and that once-daily dosing does not select more resistant bacteria. Single-dose therapy with quinolones would be an improvement in cost and patient compliance.