Ciprofloxacin concentrations in bone and muscle after oral dosing.

Ciprofloxacin, a quinoline derivative with marked gram-negative and staphylococcal activity, may be a valuable orally administered agent for use against soft-tissue and bone infections. The concentrations of this antibiotic in serum, bone, and muscle samples were determined in patients undergoing orthopedic surgery. A total of 18 patients undergoing hip or knee replacement surgery or osteotomy were randomized to receive single oral doses of ciprofloxacin (500 mg, 750 mg, or 1 g); 10 patients with osteomyelitis were given single doses of 500 or 750 mg. Mean levels in bone of more than 1 microgram/g were achieved with the 750-mg ciprofloxacin doses in patients with osteomyelitis (1.4 +/- 1 microgram/g) or with the 1-g doses in patients without infections (1.6 +/- 0.6 microgram/g). The levels in muscle were significantly higher with each increasing dose level. Orally administered ciprofloxacin (750 mg given every 12 h) should provide adequate concentrations in bones and soft tissues to treat most osteomyelitis and soft-tissue infections.