Interaction between hydroxypropyl methylcellulose and biphasic calcium phosphate after steam sterilisation: Capillary gas chromatography studies

The purpose of this study was to check the chemical stability of an injecta ble bone substitute (IBS) composed of a 50/50 w/w mixture of 2.92% hydroxyp ropyl methylcellulose (HPMC) solution in deionized water containing biphasi c calcium phosphate (BCP) granules (60% hydroxyapatite/40% beta -tricalcium phosphate w/w). After separation of the organic and mineral phases, capill ary gas chromatography (GC) was used to study the possible modification of HPMC due to the contact with BCP granules following steam sterilisation and 32 days storage at room temperature. HPMC was extracted from IBS in aqueou s medium, and a dialytic method was then used to extract calcium phosphate salts from the HPMC. The percentage of HPMC extracted from BCP was 98.5% +/ - 0.5%. as measured by UV. GC showed no chemical modifications after steam sterilisation and storage.