New segmented copolymers containing poly(epsilon-caprolactone) and etheramide segments for the controlled release of bioactive compounds.

Segmented poly(ether-ester-amide)s (PEEAs) derived from poly(epsilon-caprolactone) oligomers, sebacoyl chloride, hydrophilic diamide-diamines based on short sequences of ethylenoxy groups and containing amino acids, were used to produce matrix systems intended for the delivery of metronidazole in the periodontal pocket. PEEAs are soluble in chloroform and insoluble in water and show M(n) values in the range 8.5-18.6 kDa. The melting temperatures (53-59 degrees C) are close to that of poly(epsilon-caprolactone) (PCL) with a similar M(n). The water absorption of PEEAs is improved if compared with that of pure PCL and depends on both the length of oxyethylene sequences and the amino acid number, as well as on copolymer composition. Loaded-films containing 20% (w/w) of metronidazole were prepared by compression-molding. The release rate was diffusive in the first stage, whereas also other mechanisms, probably polymer degradation, contributed to the slower second phase. The rate of medium penetration within the film depended on PEEA hydrophilicity and crystallinity and was the main determinant governing the drug release rate. The opportunity to control effectively drug release rates by modulating the composition, and in turn the properties, of PEEAs is an attracting feature for their use in a number of drug delivery systems.