A flowable, paste-like composition capable of setting in a clinically relevant period of time into an antimicrobial agent loaded apatitic product having sufficient compressive strength to serve as a cancellous bone structural material is provided. The subject compositions are prepared by combining dry ingredients with a physiologically acceptable lubricant and an antimicrobial agent, where the dry ingredients comprise at least two different calcium phosphates. The subject compositions find use in a variety of different applications, including orthopaedic, dental and cranio-maxillofacial applications.