Sterile surgical collagen product

Claim 1

A method for preparing a surgical collagen product which has a felt- or fleece-like structure with open, communicating voids between the collagen fibers, comprising comminuting collagen-containing tissues of pigs at a temperature not exceeding 40° C, degreasing the resulting tissue pulp and simultaneously removing therefrom undesirable water-soluble non-collagen ballast substances by repeatedly treating the said tissue pulp with about a five-fold volume, based on the pulp volume, of a 5 to 15% aqueous sodium chloride solution containing about 0.2 to 1 part by weight of sodium azide as a preserving agent per 1000 parts by weight of the said solution and 0.5 to 2% by weight of a non-ionic fat-dispersing wetting agent, washing the resulting fiber pulp with water or 0.1 to 0.5% aqueous formic, acetic or citric acid, digesting the fiber pulp for 8 to 48 hours at a pH of about 2.5 to 3.5 in the five-fold volume, based on the volume of the pulp, of 0.1 to 5% aqueous acetic acid containing about 1 part by weight of pepsin per 1000 parts by weight of the tissue used as the starting material in order to remove non-collagen type proteinaceous substances and telopeptides, precipitating collagen from the resulting collagen suspension by the addition thereto of aqueous sodium chloride in such a quantity that the sodium chloride concentration of the suspension is about 3 to 5%, separating the precipitated collagen and desalting it by ultrafiltration, dialysis or washing with 60 to 75% aqueous ethyl alcohol until the salt content of the collagen is reduced to 0 to about 0.9% by weight, calculated on the weight of the dry collagen, dissolving the desalted collagen in demineralized or distilled water containing up to 3% by weight of a strong organic acid in such a proportion that the concentration of collagen in the resulting solution corresponds to a dry residue of about 0.5 to 2% by weight, freeze-drying the collagen solution, and sterilizing the freeze-dried collagen product.

Claim 2

A method for preparing a surgical collagen product which has a felt- or fleece-like structure with open, communicating voids between the collagen fibers, comprising comminuting collagen-containing tissues of pigs at a temperature not exceeding 40° C, degreasing the resulting tissue pulp and simultaneously removing therefrom undesirable water-soluble non-collagen ballast substances by repeatedly treating the said tissue pulp with about a five-fold volume, based on the pulp volume, of a 5 to 15% aqueous sodium chloride solution containing about 0.2 to 1 part by weight of sodium azide as a preserving agent per 1000 parts by weight of the said solution and 0.5 to 2% by weight of a non-ionic fat-dispersing wetting agent, washing the resulting fiber pulp with water or 0.1 to 0.5% aqueous formic, acetic or citric acid, digesting the fiber pulp for 8 to 48 hours at a pH of about 2.5 to 3.5 in the five-fold volume, based on the volume of the pulp, of 0.1 to 5% aqueous acetic acid containing about 1 part by weight of pepsin per 1000 parts by weight of the tissue used as the starting material in order to remove non-collagen type proteinaceous substances and telopeptides, precipitating collagen from the resulting collagen suspension by the addition thereto of aqueous sodium chloride in such a quantity that the sodium chloride concentration of the suspension is about 3 to 5%, separating the precipitated collagen and desalting it by ultrafiltration, dialysis or washing with 60 to 75% aqueous ethyl alcohol until the salt content of the collagen is reduced to 0 to about 0.9% by weight, calculated on the weight of the dry collagen, dissolving the desalted collagen in demineralized or distilled water containing up to 3% by weight of a strong organic acid in such a proportion that the concentration of collagen in the resulting solution corresponds to a dry residue of about 0.5 to 2% by weight, freeze-drying the collagen solution, and sterilizing the freeze-dried collagen product.