E-Decalactone

Stannous octoate has the advantage of having been used to prepare polymers (Silastic, Capronor) for which substantial toxicological data are now available (6,48). Stannous octoate-initiated polymerization has been used to prepare copolymers of e-caprolactone with other lactones, including diglycolide, dilactide, 6-valerolactone, e-decalactone, and other alkyl-substituted e-caprolactones. Conducting... 

Evidence of enzymatic degradation in vivo was first observed with a random copolymer of e-caprolactone and e-decalactone (93). 

The chain scission and weight loss of a semicrystalline copolymer with 8 mol % e-decalactone was almost identical to that of PCL and was clearly nonenzymatic. When the proportion of e-decalactone was... 

PCL was recognized as a biodegradable and non-toxic material, and a promising candidate for controlled release applications, especially for long-term dmg delivery. It m be copolymerized with many other lactones, such as glycolide, lactide, 6-valerolactone, e-decalactone, poly(ethylene oxide), and alkyl-substituted e-caprolactone. Blends of PCL with other biodegradable polymers such as PHB, PLA, and starch have been prepared. 

It could be anticipated that poly(caprolactone) containing small amounts of a comonomer would have improved use properties. The decrease in polymer crystallinity would improve both the flexibility and the drug permeability of the delivery device. Furthermore, by selecting different comonomers the rate of biodegradation could be adjusted. Two comonomers were investigated in greater detail, dilactide and e-decalactone. 

Copolymers of e-decalactone and e-caprolactone represent useful implant materials only when the decalac-tone content is very low. A change of the decalactone content from 8 to 13 mole-% has a pronounced effect on the biodegradation behavior of implants as shown by the data of Table II and Fig. 10. 

TABLE II. Biodegradation of Tritium Labeled Poly(Caprolactone-co e-decalactone) Capsules in Rabbit... 

Fig. 10 - In vivo degradation of e-decalactone-e-caprolactone (DL/CL) and dilactide-e-caprolactone (LA/CL) copolymers in tube form. Change in intrinsic viscosity of excised implants.

PCL = poly(caprolactone), PLA = racemic poly-(lactide), DL/CL = e-decalactone-co-e-caprolactone, LA/CL = racemic dilactide-co-caprolactone... 

Figure 14 Alcoholysis of e-decalactone with PEG-lipase in 1,1,1-trichloroethane at 65°C. (a) Time course of the reaction (b) rate of the reaction with PEG-lipase and unmodified lipase. (From Ref. 63.)...

In the same way, optical resolution of 8-decalactone was also demonstrated [89]. Although the stability of the substrate with a six-membered ring was much higher than that of e-decalactone with a seven-membered ring, similar enantioselectivity in the ring opening reaction was also observed when a mixture of substrates without any organic solvents was added by PEG-lipase. 

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