Absorbable sutures carbonate copolymer

Owing to its hydrolytic instability, initially, its use was limited. Currently, polyglycolide and its copolymers poly(lactic-co-glycolic acid) with lactic acid, poly(glycolide-co-caprolactone) with e-caprolactone, and poly(glycolide-co-trimethylene carbonate) with trimethylene carbonate) are widely used to develop synthetic absorbable sutures that were marketed under the trade name of Dexon and are now sold as Surgicryl [61],... 

When 1,4-butanediol is supplied in different amormts as a carbon source, P(3HB-co-4HB) is biosynthesized with 4HB contents of 5-40mol.%. This copolymer has excellent elongation to break and thermal properties for various applications. Metabolix, USA, and Tianjin Green Bioscience, China, together with DSM, The Netherlands, announced plans to produce 50 000 and 10 000 tons per year, respectively.On the other hand, Tepha, USA, produces P(4HB) (TephaFLEX) for medical applications as absorbable sutures and srugical meshes. 

Maxon absorbable suture is fabricated from copolymers of glycolide and trimethylene carbonate (l,3-dioxan-2-one) building blocks. Maxon... 

Caprosyn is one of the latest synthetic absorbable monofilament sutures from Covidien and is the only synthetic absorbable suture that is made from polyglytone 6211 copolymer having four building blocks glycolide, lactide, e-caprolactone and trimethylene carbonate. 

Absorbable suture materials are catgut (collagen derived from sheep intestinal submucosa), reconstituted collagen, polyglycolide (e.g., Dexon , Dexon II , Dexon S ), poly(glycolide/lactide) random copolymer (e.g.. Vicryl ), antimicrobial-coated Vicryl (Vicryl Plus ), poly-/ -dioxanone (e.g., PDS , PDSII PDS Plus), poly(glycolide/trimethylene carbonate) block copolymer (e.g., Maxon ), poly(glycolide/e-caprolactone) (e.g., Monocryl ,... 

This type of copolymer is prepared as A-B-A block copolymers in a 2 1 GA trimethylene carbonate (TMC) ratio, with a GA-TMC center block (B) and pure GA end blocks (A). These materials have better flexibility than pure PGA and are absorbed in approximately 7 months. This copolymer was developed to combine the predictable in vivo performance of a synthetic absorbable suture with the handling characteristics of a monofilament suture. The copolymer has a high initial tensile strength (greater than that of polydioxanone) and retains 81 % of its strength at day 14, 59 % at day 28, and 30 % at week 6. This suture is easier to handle and has greater knot security than the three bioabsorbable sutures mentioned above. 

In order to achieve the desired fiber properties, the two monomers were copolymerized so the final product was a block copolymer of the ABA type, where A was pure polyglycoHde and B, a random copolymer of mostly poly (trimethylene carbonate). The selected composition was about 30—40% poly (trimethylene carbonate). This suture reportedly has exceUent flexibiHty and superior in vivo tensile strength retention compared to polyglycoHde. It has been absorbed without adverse reaction ia about seven months (43). MetaboHsm studies show that the route of excretion for the trimethylene carbonate moiety is somewhat different from the glycolate moiety. Most of the glycolate is excreted by urine whereas most of the carbonate is excreted by expired CO2 and uriae. 

Meanwhile Ethicon (and others) developed alternative absorbable surgical sutures, based, for example, on copolymers of polyglycolide with poly-L-lactide or poly(trimethylene carbonate), and on polydioxanone, and on poly(e-oxycaproate), and also on copolymers of these with polyglycolide or with each other. These different structures made it possible to provide fibres with different rates of absorption, with different degrees of stiffness or flexibility, and for use in monofilaments, braided multifilaments, and other yam structures, as required for different surgical operations. 

As with other types of braided sutures, an absorbable coating which improves suture handUng and knot formation has been added to the absorbable braids. To minimize the risk of infection and tissue drag that are sometimes associated with braided sutures, four types of monofilament sutures have been commercialized. The absorbable monofilaments were designed specifically to approach the engineering compliance of braided sutures, by combining appropriate materials to achieve low moduli, for example, polydioxanone and copolymers of glycolide with caprolactone or trimethylene carbonate. 

Im et al (2007) have developed a manufacturing technique to produce monofilament sutures by a conjugate spinning method. Two absorbable polymers, PDS and a copolymer of / -dioxanone, trimethylene carbonate and e-caprolactone were used in this spinning method. The resulting bicomponent monofilament suture fiber (MonoFlex ) has 97 mol% / -dioxanone and exhibits the sea/islands type cross-sectional morphology shown in Fig. 11.2. These sea/island type bicomponent materials can place many fine strands... 

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