title: Surface eroding, liquid injectable polymers based on 5-ethylene ketal ε-caprolactone.
abstract: Liquid, injectable hydrophobic polymers are potentially useful as depot systems for localized drug delivery. Low molecular weight polymers of 5-ethylene ketal ε-caprolactone and copolymers of this monomer with D,L-lactide were prepared and their properties assessed with respect to their suitability for this purpose. The polymers were amorphous and of low viscosity, and the viscosity was adjustable by choice of initiator and/or by copolymerizing with D,L-lactide. Lower viscosity polymers were attained by using 350 Da methoxy poly(ethylene glycol) as an initiator in comparison to octan-1-ol, while copolymerization with D,L-lactide increased viscosity. The initiator used had no significant effect on the rate of mass loss in vitro, and copolymers with D,L-lactide (DLLA) degraded faster than 5-ethylene ketal ε-caprolactone (EKC) homopolymers. For the EKC-based polymers, a nearly constant degradation rate was observed. This finding was attributed to the hydrolytic susceptibility of the EKC-EKC ester linkage, which was comparable to that of DLLA-DLLA, coupled with a higher molecular weight of the water-soluble degradation product and the low initial molecular weight of the EKC-based polymers. Cytotoxicity of the hydrolyzed EKC monomer to 3T3 fibroblast cells was comparable to that of ε-caprolactone, suggesting that polymers prepared from EKC may be well tolerated upon in vivo implantation.
authors: Department of Chemical Engineering, Queen's University, Kingston, Ontario K7L 3N6, Canada.
authors: Oladunni Iyabo
authors: OI
authors: Babasola
authors: Brian G
authors: BG
authors: Amsden
mesh_terms: D016475:3T3 Cells; D000447:Aldehydes / Q000737:chemistry; D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000494:pharmacology; D002208:Caproates / Q000737:chemistry*; D002470:Cell Survival / Q000187:drug effects; D003692:Delayed-Action Preparations / Q000138:chemical synthesis* / Q000494:pharmacology; D004355:Drug Stability; D004952:Esters / Q000737:chemistry; D007267:Injections / Q000379:methods*; D007783:Lactones / Q000737:chemistry*; D008422:Materials Testing; D051379:Mice; D008970:Molecular Weight; D011091:Polyesters / Q000138:chemical synthesis* / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry; D013499:Surface Properties; D014783:Viscosity; D014867:Water
chemical_list: D000447:Aldehydes; D001672:Biocompatible Materials; D002208:Caproates; D003692:Delayed-Action Preparations; D004952:Esters; D007783:Lactones; D011091:Polyesters; D014867:Water; D011092:Polyethylene Glycols; C121056:caprolactone; C062968:lactide-caprolactone copolymer