LOCAL ANTIBIOTIC THERAPY WITH CALCIUM SULPHATE USED AS CARRIER FOR VANCOMYCIN AND TOBRAMYCIN: POTENTIAL SYSTEMIC TOXICITY

Abstract

Introduction: Purified plaster of Paris can be used as a resorbable carrier material for local antibiotic therapy. Clinical use already has been published with vancomycin and the aminoglycosides gentamycin and tobramycin. Calcium sulphate pellets with vancomycin can be manufactured during operation from Osteoset^® and vancomycin powder, whereas calcium sulphate with tobramycin is available as ready-to-use pellets under the brand name Osteoset T^®. Results are promising. However, no data on systemic serum levels in humans have been published so far, despite well known toxicity issues of these antibiotics in systemic therapy.

Methods: Following implantation of calcium sulphate with vancomycin or tobramycin, systemic serum levels of these antibiotics have been measured for up to 10 days, and prospectively gathered. Considering serum levels and renal function, pharmacokinetics have been estimated.

Results: Between August 2006 and February 2008, calcium sulphate with vancomycin has been implanted in 15 patients, and with tobramycin in 12 patients. Whereas vancomycin levels remained very low, tobramycin levels close to the usually accepted trough levels could be observed at 24h post-operation.

Conclusion: Vancomycin added to calcium sulphate has a safe systemic profile. On the contrary, significant serum levels of tobramycin can be measured more than 24h after implantation. Caution is mandatory when using this antibiotic, and explantation should be considered if levels too high are observed.