1、Designation: F 1925 99 (Reapproved 2005)Standard Specification forVirgin Poly(L-Lactic Acid) Resin for Surgical Implants1This standard is issued under the fixed designation F 1925; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers virgin poly(L-lactic acid) resin(or abbreviated as PLLA resin) intended for use i
3、n surgicalimplants. This specification does not cover stereoisomericcompositions based on various D, L, or DL copolymer ratios.1.2 This specification addresses material characteristics ofvirgin poly(L-lactic acid) resin and does not apply to packagedand sterilized finished implants fabricated from t
4、his material.1.3 As with any material, some characteristics may bealtered by processing techniques (such as molding, extrusion,machining, assembly, sterilization, and so forth) required forthe production of a specific part or device. Therefore, proper-ties of fabricated forms of this resin should be
5、 evaluated usingthose test methods which are appropriate to assure safety andefficacy.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t
6、his standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD 1898 Practice for Sampling of PlasticsD
7、2857 Practice for Dilute Solution Viscosity of PolymersD 3536 Test Method for Molecular Weight Averages andMolecular Weight Distribution by Liquid Exclusion Chro-matography (Gel Permeation Chromatography - GPC)D 3593 Test Method for Molecular Weight Averages andMolecular Weight Distribution of Certa
8、in Polymers byLiquid Size-Exclusion Chromatography (Gel PermeationChromatography - GPC) Using Universal CalibrationD 3892 Practice for Packaging of PlasticsF 748 Practice for Selecting Generic Biological Test Meth-ods for Materials and Devices2.2 ISO Standard:ISO 10993-9, Biological Evaluation of Me
9、dical Devices,Part 9Degradation of Materials Related to BiologicalTesting, Annex A33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 generic propertythat property which is determinedsolely by the chemical composition and structure of the virginpolymer.3.1.2 virgin polymerthe for
10、m of poly(L-lactic acid) asobtained from the manufacturer and before fabrication into amedical device.4. Virgin Poly(L-Lactic Acid) Resin Requirements4.1 Generic Properties:4.1.1 The virgin polymer shall be a homopolymer ofL-lactide with a density between 1.20 and 1.28 g/cm3(see 6.5for evaluation me
11、thod).4.1.2 The molecular mass of the virgin polymer shall beindicated by relative solution viscosity in accordance with 6.2.In addition to solution viscosity (but not in place of), weightaverage molecular mass and molecular mass distributions maybe determined by gel permeation chromatography (GPC)a
12、ccording to Test Methods D 3536 or D 3593.4.1.3 The virgin polymer shall be identified as a polylactideby infrared or1H-NMR spectroscopy.4.1.3.1 The virgin polymer shall yield an infrared spectrumwhich exhibits major absorption bands only at the wavelengthsthat appear in a suitable reference spectru
13、m. A typical infraredtransmission spectrum is shown in Fig. 1.1This specification is under the jurisdiction of ASTM Committee F04 onMedical Surgical Materials and Devices and is the direct responsibility ofSubcommittee F04.11 on Polymeric Materials.Current edition approved Mar. 1, 2005. Published Ma
14、rch 2005. Originallyapproved in 1998. Last previous edition approved in 1999 as F 1925 99e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document S
15、ummary page onthe ASTM website.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.3.2 Additional absorption bands may be indicative
16、ofknown, or unknown, impurities including residual solvents andcatalysts (refer to residual solvent limits specified in Table 1).4.1.3.3 An infrared spectrum cannot distinguish between thedifferent available stereoisomeric polylactic acids. It is usedhere only as a means of identifying the material
17、as a polylac-tide.4.1.3.4 The virgin polymer shall yield a1H-NMR spectrumwhich exhibits major absorption bands only at the frequenciesthat appear in a suitable reference spectrum.Atypical1H-NMRspectrum is shown in Fig. 2.4.1.3.5 Additional absorption bands may be indicative ofknown, or unknown, impu
18、rities including residual solvents andmonomers, and catalysts (refer to residual solvent, monomer,and tin (catalyst) limits specified in Table 1) and 4.1.5.4.1.3.6 A1H-NMR spectrum cannot distinguish betweenthe different available stereoisomeric polylactic acids. It is usedhere only as a means of id
19、entifying the material as a polylac-tide.4.1.4 The virgin polymer shall have a specific opticalrotation between 155 and 160 when measured as specifiedin 6.3.4.1.5 The virgin polymer shall have a residual monomercontent less than or equal to 2.0 % when assayed in accordancewith 6.4. Virgin polymers h
20、aving inherent viscosities greaterthan 2 dL/g and intended for injection molding or load-bearingapplications shall not have a residual monomer content greaterthan 0.1 % when assayed in accordance with 6.3.FIG. 1 Poly(L-Lactic Acid) Resin Infrared SpectrumTABLE 1 Physical/Chemical Property Requiremen
21、ts of VirginPoly(L-Lactic Acid) ResinsAnalyteResidualSolvent(s),(Total, %)ResidualWater, %Residual Tin(Sn), ppmHeavyMetals,(as Lead),ppmSulfatedAsh, %Requirement #0.01 #0.5 #200 #300 #0.1FIG. 2 Poly(L-Lactic Acid) Resin1H-NMR SpectrumF 1925 99 (2005)24.1.6 The virgin polymer shall have the chemical
22、andphysical properties as listed in Table 1 as determined by themethods listed in Section 6.5. Sampling5.1 Where applicable, the requirements of this specificationshall be determined for each lot of the virgin polymer bysampling sizes and procedures according to Practice D 1898.6. Test Methods6.1 De
23、termine the density in accordance with Test MethodD 1505.6.2 Determine the relative solution viscosity in chloroformat 30C using Practice D 2857.6.3 Determine specific optical rotation in dichloromethaneat 20C in accordance with ISO 10993-9, Annex A.6.4 Determine volume percent residual monomer by1H
24、-NMR or gas chromatography or as agreed upon by supplier andpurchaser.6.5 Determine residual solvent(s) by gas chromatography oras agreed upon by supplier and purchaser.6.6 Determine the amount of residual moisture (water) byKarl-Fischer titration, or as agreed upon by supplier andpurchaser.6.7 Dete
25、rmine the amount of residual tin (Sn) by atomicabsorption/emission (AA) spectroscopy or inductively coupledplasma (ICP) spectroscopy.6.8 Determine residual heavy metals as lead in accordancewith Method 231 of U.S. Pharmacopeia.46.9 Determine the sulfated ash content by ignition at 700C,or as agreed
26、upon by supplier and purchaser.7. Packaging and Labeling7.1 Packaging material shall meet the standards set forth inPractice D 3892.8. Biocompatibility58.1 The suitability of these materials from a human implantperspective is dependent on the specific application. Thebiologic tests appropriate for t
27、he specific site, such as recom-mended in Practice F 748 should be used as a guideline.8.2 No known surgical implant material has ever beenshown to be completely free of adverse reactions in the humanbody. However, long-term clinical experience of use of specificcompositions and formulations of this
28、 material class referred toin this specification has shown that an acceptable level ofbiological response can be expected, if the material is used toappropriate applications.9. Keywords9.1 PLLA; Poly(L-lactic acid); polylactide; virgin polymerAPPENDIX(Nonmandatory Information)X1. RATIONALEX1.1 This
29、specification is written for PLLA resin and notfor objects (for example, test samples or devices) fabricatedfrom PLLA. The properties of objects fabricated from PLLAresin, such as mechanical properties, are dependent upon theprocessing conditions used during fabrication and thus falloutside of the s
30、cope of this PLLA resin standard. Properties inthis specification are therefore specified only for PLLA resinand not for its fabricated form. Several potentially applicableASTM standards are listed in Section 2, Referenced Docu-ments, which may be followed to determine fabricated-formproperties for
31、devices and test samples fabricated from PLLAresin.X1.2 PLLA resin may be synthesized with many differentmolecular weight ranges and distribution. Each such systemwill possess unique molecular weight dependent properties.Therefore certain physical, mechanical, and thermal properties(for example, gla
32、ss transition, melt temperatures, and tensileproperties) are not specified in this document.X1.3 Most PLLA resin suppliers will provide analysesupon request relating to bioburden or pyrogens, or both.Bioburden is a measure of the number of viable cell colonies(aerobic, anaerobic, and spore cells) pe
33、r gram of resin material.Pyrogen content is a measure of the presence of bacterialendotoxins which is commonly measured by the LimulusAmebocyte Lysate test (see 2.2). Because these properties maybe significantly influenced by the exposure of the resin to anynonsterile environment, such properties ar
34、e not required in thisspecification.X1.4 While it is obviously ideal to have zero foreignparticles within any bioabsorbable implant material, underpractical processing conditions, it must be expected thatprocessing related particles of foreign matter may be present tosome degree. Unfortunately, at t
35、his time, there are no knownpublished studies dealing with typical foreign particle levels inthis resin material or their effect upon resin properties. Such aspecification may be established in the future as informationregarding this parameter is developed by methods such asround-robin use of this s
36、tandard for selected samples of PLLAresin from various commercial sources.4Method 231 of U.S. Pharmacopeia, “Heavy Metals,”, Edition XXII.5Bergsma, J.E., de Bruijin, W.C., Rozema, F.R., Bos, R.R.M., and Boering, G.,“Late Degradation Tissue Response to Poly(L-Lactide) Bone Plates and Screws,”Biomater
37、ials, 1995, pp. 16:25-31.F 1925 99 (2005)3ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and t
38、he riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision
39、of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shoul
40、dmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F 1925 99 (2005)4
