SEMISOLID HYDROPHOBIC BIOERODIBLE POLY(ORTHO ESTER) FOR POTENTIAL APPLICATION IN GLAUCOMA FILTERING SURGERY

A semi-solid poly(ortho ester) was prepared by the reaction between 1, 2,6-hexanetriol and trimethyl orthoacetate. The use of a flexible trio l such as 1,2,6-hexanetriol produces highly flexible polymers that hav e viscous behavior at room temperature. The semi-solid nature of the p olymer allows the incorporation of therapeutic agents by a simple mixi ng procedure without the need to use solvents or elevated temperatures . The release of 5-fluorouracil (5-FU) from this semi-solid polymer wa s studied in vitro. The rate of drug release was controlled by changin g the molecular weight and indirectly the viscosity of the polymers. P olymers with 3500, 5800, 10100, 15200, 33300 Da molecular weight were synthesized. Drug release ranging from one day for the 3500 Da to 7 da ys for the 33300 Da molecular weight polymer was obtained. The differe nt procedures used to modulate the polymer molecular weight during the synthesis are described. The temperature effect on the drug loaded po lymer was also studied. The results have shown that the polymer theolo gical properties and the 5-FU release were affected by this parameter. The theological study has shown that the viscosity decreased with inc reasing temperature. In the same way, the dependence between the tempe rature and the drug release was shown by the fact that only 40 wt% of 5-FU was released from the 33300 Da poly(ortho ester) after 1 1 days a t room temperature. The possibility of injecting this polymer under th e conjunctiva in the glaucoma filtering surgery therapy using a hypode rmic syringe was discussed in order to carry out in vivo 5-FU release studies.