Expanded activity and utility of the new fluoroquinolones: A review

In general, the fluoroquinolones developed over the past few years have gre ater potency, a broader spectrum of antimicrobial activity, greater in vitr o efficacy against resistant organisms, and a better safety profile than ot her antimicrobial agents, including the older quinolones. The present revie w focuses on 4 new quinolones that are commercially available (levofloxacin , trovafloxacin, grepafloxacin, and sparfloxacin) and 3 that are currently undergoing clinical trials (gatifloxacin, moxifloxacin, and clinafloxacin). Examination of the minimum inhibitory concentrations of these drugs agains t gram-positive, gram-negative, anaerobic, and atypical organisms demonstra tes their increased potency in vitro. The available clinical evidence, alth ough sparse, suggests the potential enhanced efficacy of these drugs in the treatment of various community-acquired and nosocomial infections (eg, res piratory, urinary tract, and skin infections and sexually transmitted disea ses). Compared with ciprofloxacin, their pharmacokinetic profiles demonstra te equivalent or greater bioavailability, higher plasma concentrations, and increased tissue penetration, as reflected in greater volume of distributi on. Adverse events seen with most quinolones are mild. Serious adverse effe cts that may occur are phototoxicity (particularly with sparfloxacin) and p rolongation of the QT, interval (seen with sparfloxacin and grepafloxacin). Drug interactions are possible between multivalent cation-containing compo unds and all quinolones and between theophylline and both ciprofloxacin and grepafloxacin. Drugs that prolong the QT, interval should not be coadminis tered with sparfloxacin and grepafloxacin. Step-down therapy, a therapeutic and cost-saving advantage possible with gatifloxacin, levofloxacin, and mo xifloxacin, allows the switching of patients from intravenous to oral thera py without having to change the dosage regimen or class of antibiotics. In addition to shortening the hospital stay and reducing the risk of venous co mplications, step-down therapy has been shown to cut hospital drug costs by 40% and hospitalization costs by 20%.