Concentrations of mezlocillin in the serum, heart valves, muscle and subcutaneous tissue of patients undergoing open-heart surgery.

4 g mezlocillin as a five-minute intravenous bolus were given preoperatively to 31 adult patients undergoing open-heart surgery. Mezlocillin serum levels declined from 42.8 mg/l at 1-2 h after injection to less than 1 mg/l at 6-8 h after application. Concentrations in muscle and subcutaneous tissue varied between 18 micrograms/g and less than 1 microgram/g. Mezlocillin levels in heart valves were higher than those in muscle and subcutaneous tissue, thus suggesting rapid diffusion of mezlocillin.