Calcium phosphate bone cements for local vancomycin delivery

Among calcium phosphate biomaterials, calcium phosphate bone cements (CPCs) have attracted increased attention because of their ability of self-setting in vivo and injectability, opening the new opportunities for minimally invasive surgical procedures. However, any surgical procedure carries potential inflammation and bone infection risks, which could be prevented combining CPC with anti-inflammatory drugs, thus overcoming the disadvantages of systemic antibiotic therapy and controlling the initial burst and total release of active ingredient. Within the current study α-tricalcium phosphate based CPCs were prepared and it was found that decreasing the solid to liquid phase ratio from 1.89 g/ml to 1.23 g/ml, initial burst release of vancomycin within the first 24 h increased from 40.0 ± 2.1% up to 57.8 ± 1.2% and intrinsic properties of CPC were changed. CPC modification with vancomycin loaded poly(lactic acid) (PLA) microcapsules decreased the initial burst release of drug down to 7.7 ± 0.6%, while only 30.4 ± 1.3% of drug was transferred into the dissolution medium within 43 days, compared to pure vancomycin loaded CPC, where 100% drug release was observed already after 12 days. During the current research a new approach was found in order to increase the drug bioavailability. Modification of CPC with novel PLA/vancomycin microcapsules loaded and coated with nanosized hydroxyapatite resulted in 85.3 ± 3.1% of vancomycin release within 43 days.