The current status of material used for depot delivery of drugs

Abstract

The ideal local antibiotic delivery system has not been created. Antibiotic-laden bone cement has become the gold standard in the treatment of infected orthopaedic implants and there are confirmatory laboratory and clinical data that support the use of these materials. Heat-stable antibiotics elute from antibiotic-laden bone cement and do not have a notable influence on the compressive strengths of bone cement if the antibiotics are used in appropriate amounts. If the proper antibiotic is chosen, placed in the appropriately porous materials in sufficient amounts, and implanted in bone, antibiotic levels in the surrounding bone are many times greater than can be achieved by safe systemic antibiotic doses. Although the materials that have been manufactured commercially have been used for over 30 years in Europe, until recently, they have not been available in the United States. Currently, there are five antibiotic-laden bone cement composites that have been approved by the FDA and that are available for clinical use. Studies are being done to search for biodegradable implants preferable to antibiotic-laden bone cement; however, these studies and the materials are still in early stages and development. Currently, there are no FDA-approved biodegradable materials available for use to treat infected orthopaedic implants. As new materials become available and their elution characteristics are recorded, it is important for surgeons to understand how the data were collected so they can have a clear understanding of the elution characteristics of the material used and how the material acts in different environments. Even with extensive historic, clinical, and research data that prove the effectiveness of antibiotic-laden cement, the ideal drug delivery system is neither agreed on nor available.