Local Administration of Antibiotics with an Implantable Osmotic Pump

Abstract

A totally implantable drug pump was evaluated as a delivery system in the treatment of osteomyelitis. Gentamicin levels in rabbit serum and bone obtained by systemic administration are compared with levels in rabbit serum and bone obtained by local administration via an implantable drug pump. Systemic administration gave mean gentamicin bone levels ranging from less than 1 microgram/gm to 3.6 micrograms/gm, while drug pump administration gave bone levels ranging from 10.8 micrograms/gm to 64.0 micrograms/gm (micrograms = microgram, or 10(-6) gram). To evaluate the drug pump as a mode of therapy, acute staphylococcal osteomyelitis was induced in ten rabbits. Drug pumps filled with amikacin were inserted in five of the infected animals. Three of these were culture-negative at one week. One had a scant growth of Staphylococcus from the pump, and one had scant growth from the pump and the wound. Clinically, none of these five rabbits appeared infected at seven days. The remaining five rabbits were all culture-positive, with heavy growths of staphylococci from their wounds, and clinically, all appeared grossly infected at seven days. These data demonstrate that high local and low systemic levels of antibiotics can be achieved with an implantable drug pump and that this method can sterilize an infected musculoskeletal wound. Therefore, antibiotic administration via an implantable drug pump is an important potential mode of therapy in the treatment of osteomyelitis.