Antibiotic stability in an implantable pump.

We measured the stability of vancomycin, amikacin, netilmicin, tobramycin, gentamicin, clindamycin, and aztreonam in an implantable drug pump. Two pumps were filled with the antibiotic being tested and were incubated at 37 degrees for 3 weeks. Samples were taken daily. At 3 weeks the pumps were disassembled and examined microscopically for signs of deterioration. If the pumps were intact, bioassays were used to quantitate the biologic activity of each daily antibiotic sample. Vancomycin degraded the pump. Amikacin, netilmicin, tobramycin, gentamicin, clindamycin, and aztreonam had no effect on the pump and maintained their biologic activity over the 3-week period.