Summary and Conclusions
Physical aging of 2 types of PEO could be tracked by the combination of PALS, DSC, and SEM methods. After storing the samples at 40°C±2°C and 75%±5% RH, a decrease in the o-Ps lifetime values and an increase in the melting enthalpies as a function of storage time indicated a reorientation of the polymer chains. The limitations of monitoring enthalpy relaxation confirm the importance of methods that track volume relaxation, such as PALS. Structural changes could be observed even after a short storage time (4 weeks), which highlights the effect of further investigations of the influence of physical aging on the properties of PEO-containing dosage forms.
Keywords: Poly(ethylene oxide), physical aging, positron annihilation lifetime spectroscopy, differential scanning calorimetry, amorphous
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References
- 1.Rowe RC, Sheskey PJ, Weller PJ, editors. Handbook of Pharmaceutical Excipients. 4th ed. London, UK: Pharmaceutical Press; 2003. pp. 460–461. [Google Scholar]
- 2.Hutchinson JM. Physical aging of polymers. Prog Polym Sci. 1995;20:703–760. doi: 10.1016/0079-6700(94)00001-I. [DOI] [Google Scholar]
- 3.Hay JN. The physical ageing of amorphous and crystalline polymers. Pure Appl Chem. 1995;67:1855–1858. doi: 10.1351/pac199567111855. [DOI] [Google Scholar]
- 4.Süvegh K, Zelkó R. Physical aging of poly(vinylpyrrolidone) under different humidity conditions. Macromolecules. 2002;35:795–800. doi: 10.1021/ma011148l. [DOI] [Google Scholar]
- 5.Zelkó R, Süvegh K. Comparison of the enthalpy recovery and free volume of poly(vinylpyrrolidone) during anomalous glassy to rubbery transition. Eur J Pharm Sci. 2004;21:519–523. doi: 10.1016/j.ejps.2003.11.013. [DOI] [PubMed] [Google Scholar]
- 6.MacKenzie IK. Experimental Methods of Annihilation Time and Energy Spectrometry. In: Brandt W, Dupasquier A, editors. Positron Solid-State Physics. Amsterdam, The Netherlands: Elsevier; 1983. pp. 196–264. [Google Scholar]
- 7.Süvegh K, Vértes A, Hyodo T. Positronium as a sensitive detector of changes in molecular structure. Adv Mol Struct Res. 1999;5:313–357. doi: 10.1016/S1087-3295(99)80010-3. [DOI] [Google Scholar]
- 8.Zelkó R, Süvegh K. Correlation between the release characteristics of theophylline and the free volume of polyvinylpyrrolidone. Eur J Pharm Sci. 2005;24:351–354. doi: 10.1016/j.ejps.2004.11.009. [DOI] [PubMed] [Google Scholar]
- 9.Vernel J, Rychwalski RW, Pelisek V, Saha P, Schmidt M, Maurer FHJ. Physical aging in poly(ethylene oxide)/atactic-poly(methyl methacrylate) blends. Thermochim Acta. 1999;342:115–137. doi: 10.1016/S0040-6031(99)00291-9. [DOI] [Google Scholar]
- 10.Zhao Y, Jasse B, Monnerie L. Orientation and relaxation in uniaxially stretched poly(methyl methacrylate)-poly(ethylene oxide) blends. Polym J. 1989;30:1643–1650. doi: 10.1016/0032-3861(89)90324-8. [DOI] [Google Scholar]
- 11.Jin X, Zhang S, Runt J. Observation of a fast dielectric relaxation in semi-crystalline poly(ethylene oxide) Polym J. 2002;43:6247–6254. doi: 10.1016/S0032-3861(02)00560-8. [DOI] [Google Scholar]
- 12.FDA/CDER . Guidance for Industry: Q1A(R2) Stability Testing of New Drug Substances and Products. Rockville, MD: Center for Drug Evaluation and Research, Center for Biologics Evaluation and Research, Food and Drug Administration; 2003. [Google Scholar]
- 13.Committee for Proprietary Medicinal Products . Guideline on Stability Testing of Existing Active Substances and Releated Finished Products. London, UK: The European Agency for the Evaluation of Medicinal Products; 2003. [Google Scholar]
- 14.Wunderlich B. Crystal Melting: Macromolecular Physics. New York, NY: Academic Press; 1980. [Google Scholar]
- 15.Bamford D, Reiche A, Dlubek G, Alloin F, Sanchez J-Y, Alam MA. Ionic conductivity, glass transition, and local free volume in poly (ethylene oxide) electrolytes: single and mixed ion conductors. J Chem Phys. 2003;118:9420–9432. doi: 10.1063/1.1567717. [DOI] [Google Scholar]
- 16.Netti PA, Ambrosio L, Del Nobile MA, Mensitieri G, Nicolais L. Water transport in hyaluronic acid esters. J Bioact Compat Polym. 1996;11:312–316. [Google Scholar]