fluoroquinolones

A class of antibiotics with a broad spectrum of antimicrobial activity; well-absorbed orally, with good tissue penetration and relatively long duration of effect.The f., introduced in the 1980s, are particularly useful in Gram-negative infections. Nalidixic acid, a nonfluorinated quinolone, has been used for several decades to treat urinary tract infections, but its value is limited by poor systemic distribution and rapid development of bacterial resistance. In contrast, the f., which contain a fluorine atom, rapidly achieve therapeutic concentration in plasma, tissues, and urine after oral administration, and resistance develops slowly. The fluorine atom also broadens the spectrum of these agents, conferring activity against some Gram-positive bacteria. They are useful in susceptible infections of the respiratory tract, urinary tract, skin, and bone. Several of these agents are approved for single-dose oral treatment of uncomplicated gonorrhea. They are generally inactive against anaerobes and β-hemolytic streptococci. Fluoroquinolone antibiotics inhibit bacterial DNA gyrase, which is necessary for the replication of DNA as well as of plasmids involved in certain types of bacterial resistance. Elimination is primarily renal, and dosage must be adjusted for patients with renal failure. The f. are generally well tolerated. The most frequent side effect s are nausea, abdominal distress, and dizziness. The drugs accumulate in articular cartilage and can cause severe damage during rapid growth of that tissue; hence they are contraindicated in persons under 18. Use during strenuous exercise may be hazardous to joints and can cause tendon rupture. These drugs may interfere with the hepatic biotransformation of theophylline and warfarin.