Quinolones in the elderly.

Aging results in a number of physiological changes that can affect drug disposition; these include reduced gastric acidity, decreased intestinal motility, lower lean body mass, and reduction in renal function. The age-related decline in renal function is the most important of these factors when administering quinolones to elderly patients. Elimination half-life (t1/2) values are prolonged in proportion to the degree to which the compound is normally eliminated by the renal route. Thus, age-related increases in t1/2 occur to a greater degree with ofloxacin (80 to 90% renal elimination) than with ciprofloxacin, which is also excreted by the gastro-intestinal route. Norfloxacin, pefloxacin, and sparfloxacin may also be eliminated to a substantial degree by the transintestinal route, as their excretion is not substantially affected by severe renal impairment. Prolonged drug elimination in the elderly can result in an increased incidence of adverse effects. Ofloxacin causes a higher frequency of drug-related events in the elderly, presumably reflecting the prolonged serum t1/2 and higher serum concentrations, and consequently higher tissue levels in this age group. Indeed, dosage reduction is recommended when treating elderly patients with ofloxacin, but does not appear necessary on the basis of advanced age for ciprofloxacin, norfloxacin and pefloxacin.