Stability of ampicillin, carbenicillin, clindamycin, kanamycin, cephalothin, methicillin, and penicillin was tested in each of seven parenteral solutions (Isolyte M and Isolyte P, Ringer's lactate, 5% dextrose in water, 10% dextrose in water, dextrose in normal saline and normal saline) at three temperatures (4°C, 25°C, and 37°C). Each antibiotic was reconstituted to a predetermined concentration with bacteriostatic water and immediately added (zero time) to each solution at each temperature. Aliquots were obtained at 30 minutes and at 1, 2, 4, 6, and 12 hours and tested for antibacterial activity. Ampicillin activity fell in most solutions reaching nondetectable levels in Ringer's lactate at 24 hours at 37°C. Minimal loss of activity was demonstrable in Isolyte M and Isolyte P solutions at 24 hours. Carbenicillin, clindamycin, kanamycin, methicillin, and penicillin generally retained 90% of their initial activity at 24 hours in all solutions and at all temperatures. Cephalothin activity was retained for 24 hours in all solutions at 4°C and 25°C and at 37°C until 6 hours; thereafter, antimicrobial activity decreased in solutions at 37°C. The stability of ampicillin in multiple electrolyte solutions containing acetate contrasted sharply with loss of activity in solutions containing lactate.
Normal saline versus lower-chloride solutions for kidney transplantation
