Controlled adsorption and release onto calcium phosphates materials and drug delivery applications
1 LPCME-CNRST-URAC 20, FSSM, BP. 2390, Université Cadi Ayyad, 40000 Marrakech, Maroc
2 Université de Toulouse, CIRIMAT, UPS-INPT-CNRS, ENSIACET, 4 allée Emile Monso, BP. 44362, 31030 Toulouse, France
3 Université de Toulouse, CIRIMAT, UPS-INPT-CNRS, Université Paul Sabatier, Faculté de Pharmacie, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
4 Laboratory for the Study of Skeletal Disorders and Rehabilitation, Department of Orthopaedic Surgery, Harvard Medical School, Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
The adsorptive properties of synthetic calcium phosphates analogous to bone mineral were examined with respect to cisplatin and risedronate, two biological active drugs; the uptake and release experiments were carried out under various conditions in order to understand the basic mechanism of interaction. The effect of temperature and solution composition were highlighted and discussed. The adsorption results obtained for the therapeutic agents demonstrated that, depending on the conditions investigated (nature of the sorbent, concentration range, ionic composition, temperature…), the shape of the isotherms is of Freundlich or Langmuir type. The adsorption is described as an ion-exchange process in dilute solutions, while the interaction appears to be reactive for concentrated solutions (dissolution of mineral ions from the apatite substrate and formation of soluble calcium complex and/or precipitation of calcium salts involving sorbate molecules). The information gained on the surface reactivity of calcium phosphate were exploited to associate an antibiotic to calcium phosphate cements for drug delivery applications. The specimens were obtained by combination of calcium phosphate and calcium carbonate powders upon mixing with water. The physicochemical properties of the paste were altered by the drug loading method (in the liquid or solid phase). Thus, a dose-dependent effect was noticed for the paste setting time, hardening and the release process.
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