ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The physical characterization of hydroxypropylcellulose-indomethacin grafts (HPC-IND) is described. Using size-exclusion chromatography (SEC) and serial differential refractive index (dRI) and ultraviolet spectrophotometric (UV) detection methods, it was possible to characterize the chemical substitution of the HPC-IND graft. Using the acid chloride of IND as the reactive intermediate, the HPC-IND graft was synthesized. The amount of IND grafted onto the polymer as a function of the HPC molecular weight (MW) was then quantitatively estimated. It was found that the substitution of IND onto the HPC was not uniform, representing chemical heterogeneity of the first kind. Increasingly higher substitution (of IND to HPC) was observed as the MW decreased (〈250,000 Daltons) for the HPC backbone. Lower, more uniform substitution was observed for the higher molecular weight regions of the HPC (〉250,000 Daltons). Possible contributing factors affecting the observed nonuniform substitution include (1) the chain coiling of the HPC in solution, thus limiting the availability of the pendant hydroxyl groups, (2) nonuniform substitution of the hydroxypropyl moiety onto the cellulose backbone, and (3) steric effects resulting from the incorporation of the bulky aromatic drug molecule onto the backbone HPC.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1991.070420815
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