High-strength resorbable brushite bone cement with controlled drug-releasing capabilities

• Published in: Acta biomaterialia Vol. 5; no. 1; pp. 43 - 49
• Main Authors: Hofmann, M.P., Mohammed, A.R., Perrie, Y., Gbureck, U., Barralet, J.E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 2009
• Subjects: Anti-Bacterial Agents - chemistry; Antibiotics; Biocompatible Materials - chemistry; Bone cement; Bone Cements - chemistry; Brushes; Brushite; Calcium phosphate cement; Calcium Phosphates - administration & dosage; Calcium Phosphates - chemistry; Cements; Ceramics; Ciprofloxacin - administration & dosage; Citric Acid - chemistry; Compressive strength; Consumption; Controlled drug release; Drug Delivery Systems; Mechanical properties; Microscopy, Electron, Scanning; Models, Chemical; Particle Size; Porosity; Powders; Pressure; Stress, Mechanical; Vancomycin; Vancomycin - administration & dosage; Brushite; Mechanical properties; Calcium phosphate cement; Bone cement; Controlled drug release
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2008.08.005

Brushite cements differ from apatite-forming compositions by consuming a lot of water in their setting reaction whereas apatite-forming cements consume little or no water at all. Only such cement systems that consume water during setting can theoretically produce near-zero porosity ceramics. This study aimed to produce such a brushite ceramic and investigated whether near elimination of porosity would prevent a burst release profile of incorporated antibiotics that is common to prior calcium phosphate cement delivery matrices. Through adjustment of the powder technological properties of the powder reactants, that is particle size and particle size distribution, and by adjusting citric acid concentration of the liquid phase to 800
mM, a relative porosity of as low as 11% of the brushite cement matrix could be achieved (a 60% reduction compared to previous studies), resulting in a wet unprecompacted compressive strength of 52
MPa (representing a more than 100% increase to previously reported results) with a workable setting time of 4.5
min of the cement paste. Up to 2
wt.% of vancomycin and ciprofloxacin could be incorporated into the cement system without loss of wet compressive strength. It was found that drug release rates could be controlled by the adjustable relative porosity of the cement system and burst release could be minimized and an almost linear release achieved, but the solubility of the antibiotic (vancomycin
>
ciprofloxacin) appeared also to be a crucial factor.