Surgical suture abstract
The invention provides a surgical suture comprising a suture body
and a coating layer comprising ingredients A, B and C: <ingredient
A> at least one higher fatty acid salt; <ingredient B>
at least one film-forming polymer selected from the group consisting
of polycaprolactone, caprolactone-lactic acid copolymer, caprolactone-glycolic
acid copolymer, polylactic acid and lactic acid-glycolic acid copolymer;
and <ingredient C> at least one sucrose fatty acid ester;
and method for preparation thereof.
Surgical suture claims
What we claimed is:
1. A surgical suture comprising a suture body and a coating layer
comprising ingredients A, B and C:
<ingredient A> at least one higher fatty acid salt;
<ingredient B> at least one film-forming polymer selected
from the group consisting of polycaprolactone, caprolactone-lactic
acid copolymer, caprolactone-glycolic acid copolymer, polylactic
acid and lactic acid-glycolic acid copolymer; and
<ingredient C> at least one sucrose fatty acid ester.
2. A surgical suture according to claim 1 further comprising a
coating layer comprising ingredient B as an essential component.
3. A surgical suture according to claim 1 further comprising a
coating layer comprising ingredient C as an essential component.
4. A surgical suture according to claim 1 wherein said higher fatty
acid salt comprises C.sub.12 -C.sub.22 fatty acid.
5. A surgical suture according to claim 4 wherein said higher fatty
acid salt is calcium stearate.
6. A surgical suture according to claim 1 wherein a proportion
of ingredients A, B and C meets the condition of A>C.gtoreq.B.
7. A surgical suture according to claim 1 wherein an amount of
said coating layer is about 2-5% by weight when taking an amount
of the suture body as 100% by weight.
8. A surgical suture according to claim 1 wherein said suture body
is an absorbable braid suture.
9. A surgical suture according to claim 8 wherein said absorbable
braid suture is made of polyglycolic acid.
10. A surgical suture comprising a suture body, a first coating
layer comprising ingredients A and B, and a second coating layer
comprising ingredient C:
<ingredient A> at least one higher fatty acid salt;
<ingredient B> at least one film-forming polymer selected
from the group consisting of polycaprolactone, caprolactone-lactic
acid copolymer, caprolactone-glycolic acid copolymer, polylactic
acid and lactic acid-glycolic acid copolymer; and
<ingredient C> at least one sucrose fatty acid ester.
11. A method for preparing a surgical suture comprising
(i) dissolving or dispersing in a solvent a composition which comprises
at least one higher fatty acid salt and at least one film-forming
polymer selected from the group consisting of polycaprolactone,
caprolactone-lactic acid copolymer, caprolactone-glycolic acid copolymer,
polylactic acid and lactic acid-glycolic acid copolymer and at least
one sucrose fatty acid ester; and
(ii) making to adhere said composition to said suture body to form
a coating layer.
12. A method for preparing a surgical suture comprising steps of:
(i) forming a first coating layer by dissolving or dispersing a
composition which comprises at least one higher fatty acid salt
and at least one film-forming polymer selected from the group consisting
of polycaprolactone, caprolactone-lactic acid copolymer, caprolactone-glycolic
acid copolymer, polylactic acid and lactic acid-glycolic acid copolymer,
followed by making to adhere said composition to said suture body;
and
(ii) forming a second coating layer by making to adhere said sucrose
fatty acid ester to said suture with a first coating layer obtained
by the step (i).
Surgical suture description
FIELD OF THE INVENTION
The present invention relates to surgical sutures and methods for
preparation thereof.
BACKGROUND ART
Surgical sutures are requested to have properties of nontoxicity,
appropriate smoothness, high knot strength, etc. In order to impart
the properties to surgical sutures, proposed are sutures prepared
by coating suture bodies consisting of bioabsorbable polymers such
as homopolymer or copolymer of lactide, glycolide, etc., with higher
fatty acid salts (U.S. Pat. No. 4532929); compositions comprising
higher fatty acid salts and film-forming polymers, such as poly(p-dioxanone),
polycaprolactone and polyethyleneoxide (U.S. Pat. Nos. 4201216;
4624256; 5378540; and 5380780); sucrose fatty acid esters
(U.S. Pat. No. 4844067).
When only higher fatty acid salts are attached to suture bodies,
however, a problem of easy strip of coating layer arises. Although
sutures coated with compositions comprising higher fatty acid salts
and film-forming polymers, such as poly(p-dioxanone), polycaprolactone
and polyethyleneoxide, have improved lubricating properties, said
sutures have a problem of decreased knot strength. Sutures coated
with sucrose fatty acid esters are fair in properties of smoothness
and knot strength. However, said sutures are requested to have further
improved properties.
Maintenance of knot strength of sutures becomes difficult in proportional
to improvement of smoothness of sutures leading to higher slip properties
thereof.
It is an object of the invention to provide surgical sutures having
outstanding properties in both smoothness and knot strength without
toxicity.
DISCLOSURE OF THE INVENTION
The inventors conducted extensive research in consideration of
said problems of prior art, and found that smoothness and knot strength
of sutures are further improved by forming a coating layer comprising
higher fatty acid salts and film-forming polymers and further comprising
sucrose fatty acid esters.
Thus, the invention provides the following surgical sutures and
methods for preparing thereof.
1. A surgical suture comprising a suture body and a coating layer
comprising ingredients A, B and C:
<ingredient A> at least one higher fatty acid salt;
<ingredient B> at least one film-forming polymer selected
from the group consisting of polycaprolactone (hereinafter referred
to as "PCL"), caprolactone-lactic acid copolymer (hereinafter
referred to as "P-CL/LA"), caprolactone-glycolic acid
copolymer (hereinafter referred to as "P-CL/GA"), polylactic
acid (hereinafter referred to as "PLA") and lactic acid-glycolic
acid copolymer (hereinafter referred to as "P-LA/GA");
and
<ingredient C> at least one sucrose fatty acid ester. (hereinafter
referred to as "first invention")
2. A surgical suture comprising a suture body, a first coating
layer comprising ingredients A and B, and a second coating layer
comprising ingredient C:
<ingredient A> at least one higher fatty acid salt;
<ingredient B> at least one film-forming polymer selected
from the group consisting of PCL, P-CL/LA, P-CL/GA, PLA and P-LA/GA;
and
<ingredient C> at least one sucrose fatty acid ester. (hereinafter
referred to as "second invention")
3. A method for preparing a surgical suture comprising
(i) dissolving or dispersing in a solvent a composition which comprises
at least one higher fatty acid salt and at least one film-forming
polymer selected from the group consisting of PCL, P-CL/LA, P-CL/GA,
PLA and P-LA/GA and at least one sucrose fatty acid ester; and
(ii) making to adhere said composition to said suture body to form
a coating layer. (a method for producing a surgical suture of first
invention).
4. A method for preparing a surgical suture comprising steps of:
(i) forming a first coating layer by dissolving or dispersing a
composition which comprises at least one higher fatty acid salt
and at least one film-forming polymer selected from the group consisting
of PCL, P-CL/LA, P-CL/GA, PLA and P-LA/GA, followed by making to
adhere said composition to said suture body; and
(ii) forming a second coating layer by making to adhere said sucrose
fatty acid ester to said suture with a first coating layer obtained
by the step (i). (a method for producing a surgical suture of second
invention).
With respect to first invention
The first invention is described below in detail.
Examples of higher fatty acids of higher fatty acid salts employed
as ingredient A are C.sub.10 -C.sub.30 fatty acids, preferably C.sub.12
-C.sub.22 fatty acids, more preferably C.sub.12 -C.sub.18 fatty
acids. Said higher fatty acids are saturated or unsaturated, and
may be branched.
Specifically, said higher fatty acids include lauric acid, myristic
acid, palmitic acid, stearic acid, oleic acid, palmitoleic acid,
eicosanoic acid and docosanoic acid, preferably include lauric acid,
myristic acids palmitic acid and stearic acid.
Examples of salt of higher fatty acid salts are sodium, potassium
and like alkali metal salts, calcium, magnesium and like alkaline
earth metal salts, preferably calcium and magnesium salts, more
preferably calcium salt.
Calcium stearate is a particularly preferable higher fatty acid
salt as ingredient A.
Ingredient B comprises at least one film-forming polymer selected
from the group consisting of PCL, P-CL/LA, P-CL/GA, PLA and P-LA/GA.
Preferable film-forming polymer include PCL, PLA and P-CL/LA.
Ingredient C comprises at least one sucrose fatty acid ester. Said
sucrose fatty acid esters have 1-8 fatty acid or acids, preferably
2-8 fatty acids linked with sucrose by an ester bond. Fatty acids
linked with sucrose are not specifically limited to, but include
C.sub.2 -C.sub.22 fatty acids. Said fatty acid esters are esters
linked with one type of fatty acid or mixed ester linked with 2
or more types of fatty acids. Preferable fatty acids include stearic
acid, palmitic acid, lauric acid and myristic acid.
An amount of said coating layer comprising ingredients A B and
C is about 0.5-10% by weight, preferably about 2-5% by weight when
taking an amount of the suture body as 100% by weight. The amount
of said coating layer ranging about 2-5% by weight leads to improved
smoothness, inhibition of strip of said coating layer in the form
of powder and maintenance of knot strength of suture substantially
as high as knot strength of the suture body, thereby preferable.
The surgical suture of the first invention comprising said coating
layer and said suture body includes sutures, inside of which said
composition enters and adheres to, besides said coating layer is
formed outside of said suture body. Therefore, said weight of coating
layer means a total weight of inside and outside of the suture body.
Conventional sutures may be employed as the suture body of the
invention. Materials thereof include bioabsorbable materials such
as polyglycolic acid and glycolic acid-lactic acid copolymer, silk,
polyester and complex thereof, preferably include polyglycolic acid.
Said suture body is prepared in the form of monofilament, braid,
twisted yarn, etc., preferably braid. A particularly preferable
suture body is a braid suture made of bioabsorbable polymer.
Said surgical sutures of the first invention and second invention
may be prepared by forming a coating layer on monofilament or multifilament,
followed by braiding monofilament or multifilament covered by said
coating layer. Said surgical sutures may also be prepared by forming
coating layer on multifilament having a braid structure. The surgical
sutures of the invention include both of them.
A proportion of ingredients A, B and C preferably meets the condition
of A>C.gtoreq.B.
Preferable concentrations of each ingredient in a solvent are about
5-8% by weight (ingredient A); about 0.5-2% by weight (ingredient
B); and about 1-3% by weight (ingredient C).
The amounts of said ingredients contained in the surgical suture
are:
Ingredient A=about 1.0-3.5% by weight;
Ingredient B=about 0.1-0.5% by weight; and
Ingredient C=about 0.3-1.5% by weight;
The surgical suture of the first invention include the following
suture further having an outer layer comprising ingredient B or
ingredient C.
* a surgical suture composed of a suture body, a coating layer
I comprising ingredients A, B and C, and a coating layer II comprising
ingredient B (ingredients A, B and C are as defined above).
* a surgical suture composed of a suture body, a coating layer
I comprising ingredients A, B and C, and a coating layer II' comprising
ingredient C (ingredients A, B and C are as defined above).
With respect to said surgical suture having two coating layers,
a weight ratio of the coating layer I to the coating layer II; and
a weight ratio of the coating layer I to the coating layer II' are
the same as a weight ratio of the second invention below. A weight
ratio of ingredients A, B and C of said coating layer I is as defined
above.
The surgical suture of the first invention may be produced by dissolving
or dispersing in a solvent a composition comprising ingredients
A, B and C, followed by making to adhere said composition to a suture
body. Examples of the solvent used in said method are ethanol, isopropanol
and like alcohols, dichloromethane, chloroform and like halogenated
hydrocarbons, acetone, methylethylketone and like ketones, ethyl
acetate and like esters, which are used individually or in a mixture
of two or more.
Adhesion of said composition to the suture body so as to form a
coating layer is usually carried out by dipping a suture body in
the solution or dispersion of said composition, followed by drying
the solvent. Adhesion may also be carried out by spraying or coating
said solution or dispersion to the suture body, followed by drying
the solvent.
The coating layer of first invention may include a variety of additives
other than ingredients A, B and C. Said additives include antibiotics,
colorants, etc.
With respect to second invention
Ingredients A, B and C are the same as those of the first invention.
The amount of first coating layer ranges about 0.5-8.0% by weight,
preferably about 1.5-4.0% by weight when taking an amount of suture
body as 100% by weight.
The amount of second coating layer ranges about 0.1-2.0% by weight,
preferably about 0.3-1.5% by weight when taking an amount of suture
body as 100% by weight.
The borderline of first coating layer and second coating layer
may be clearly formed. Alternatively, a borderline region may be
formed by a mixture of ingredients A, B of first coating layer and
ingredient C of second coating layer. In this case, outer surface
of second coating layer is occupied by ingredient C.
Therefore, the first coating layer means a coating layer whose
major components are ingredients A and B, and the second coating
layer means a coating layer whose major component is ingredient
C.
The surgical suture of second invention may be prepared by steps
of
(i) dissolving or dispersing in a solvent a composition of ingredients
A and B, followed by making to adhere said composition to suture
body so as to form the first coating layer; and
(ii) dissolving in a solvent ingredient C, followed by making to
adhere ingredient C to said first coating layer so as to form the
second coating layer according to the procedure of the first invention.
The solvent dissolving or dispersing ingredients A and B, and the
solvent dissolving ingredient C are as defined above.
When hexane, benzene and like solvents which are difficult to dissolve
ingredients A and B are employed as the solvent of ingredient C,
the borderline of first coating layer and second coating layer become
clear.
The coating layers may contain antibiotics, colorants, etc.
According to the invention, surgical sutures having the properties
of nontoxicity, strong knot strength, outstanding smoothness and
least strip of powder of treating agents coated are provided.
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