Pharmacokinetics of single-dose oral ciprofloxacin in infants and small children.

The pharmacokinetics of orally administered ciprofloxacin (CIP) was studied in seven infants aged 5 to 14 weeks and nine children aged 1 to 5 years, most of whom were Salmonella carriers. In each case, 15 mg of CIP per kg of body weight was given with water on an empty stomach, and timed serum samples were taken during the following 12 h. The elimination half-life of CIP was significantly (P less than 0.001) longer in the infants (2.73 +/- 0.28 h; mean +/- standard deviation) than it was in the children (1.28 +/- 0.52 h). The area under the serum CIP concentration-time curve (AUC) from time zero to infinity was 16.1 +/- 7.4 mg.h.liter-1 among the infants and 5.3 +/- 3.3 mg.h.liter-1 in the children (P less than 0.01). No significant differences in the maximum concentration in serum, time to maximum concentration in serum, or absorption half-life were observed between the two groups. In contrast, the mean residence time was twofold longer in the infants (4.6 h) than it was in the children (2.4 h; P less than 0.001). The findings suggest that elimination of CIP is particularly rapid in children who just have passed infancy; they may require doses at shorter time intervals than those required by infants or older children or adults. In general, an oral dose of 10 to 15 mg of CIP per kg three times daily seems appropriate for children aged 1 to 5 years.