Absorbable coating composition for sutures

#1. Field of the Invention

#This invention relates to an absorbable composition useful as a coating and lubricating finish for surgical sutures. More particularly, this invention relates to a means for improving the tie-down properties of synthetic absorbable multifilament sutures by coating the sutures with an absorbable lubricating composition.

#2. Description of Prior Art

#Forty-five parts of a low molecular weight (.eta.inh 1.5 in HFIP) lactide/glycolide copolymer [65 mol % L(-) lactide and 35 mol % glycolide]and forty-five parts of calcium stearate* were placed in a porcelain pebble mill with 810 parts of 1,1,2-trichloroethane. Dissolving of the lactide/glycolide copolymer and dispersion of the calcium stearate were accomplished simultaneously by milling the mixture for two days. The solution/dispersion (Brookfield viscosity of 218 CPS at 35.degree. C.) was then transferred to a suture coating bath. A size 3-0 braided suture of 90/10 (weight percent) glycolide/lactide copolymer was coated with the composition by passing the suture through the mixture while using a folded felt pad to wipe excess material from the suture as it exited the coating bath. The suture was coated at a speed of 8 feet per minute which provided an immersion time of about 5 seconds in the coating bath. After passing through the coating bath and the felt wiping pads, the suture immediately entered a drying tower where enough solvent was removed to render the suture tack free by the time the first guide was contacted. Drying was completed by winding the coated braid on a spool and keeping it in vacuum at 100 microns for two days. The coating solids pick-up was determined to be 5.3% of the uncoated braid. The suture was finished by winding the coated braid on an annealing rack under mild tension and heating 10 minutes at 110.degree. C.

#Using afore described semi-quantitative smoothness-of-tie-down test, the coated braid in a single throw knot tie-down rated 8-9 dry, and 8 wet. The tensile strength of the coated braid was 9.9 lbs. under straight tension and 5.4 lbs. knotted, while in the uncoated control, tensiles were 9.9 lbs. and 5.8 lbs., respectively. Braided synthetic absorbable sutures coated in a similar manner were sterilized with ethylene oxide and implanted in animals. After 21 days, the strength of the coated braid was the same as in the uncoated control, and absorption was almost complete at 90 days, indicating that the coating composition or method of application had no significant effect on suture tensile strength or absorbability.

#Using a coating solution/dispersion identical in composition to that in Example 1 except that total solids were 6% rather than 10%, the glycolide/lactide braided suture was coated by the same method. After vacuum drying, the coating solids pick-up was found to be 2.9% based on the uncoated braid.