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Change in the V/B Polymorph Ratio and T 1 Relaxation of Epichlorohydrin Crosslinked High Amylose Starch Excipient
Author(s) -
Shiftan Dror,
Ravenelle Francois,
Mateescu M. Alexandre,
Marchessault Robert H.
Publication year - 2000
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/1521-379x(200007)52:6/7<186::aid-star186>3.0.co;2-8
Subject(s) - epichlorohydrin , excipient , amorphous solid , amylose , starch , materials science , crystallization , crystallography , relaxation (psychology) , paracrystalline , chemistry , chemical engineering , polymer chemistry , organic chemistry , chromatography , psychology , social psychology , engineering
High amylose epichlorohydrin crosslinked starch excipient was examined to gain understanding of the starch polymorph changes as the crosslinking degree (CLD) increases. When the crosslinking degree is high, the sample is mostly amorphous, and the V/B ratio decreased. For this sample, “humidification” or “water soaking”, cannot overcome crystallization restraint due to the high crosslinking degree. The water soaked 20% CLD sample show some sharp, low intensity double helix 13 C resonances. This sample is paracrystalline as can be seen from the collapse of the C(1) doublet to a singlet. Relaxation studies show that increasing crosslinking degree increases the amorphous content. It is also suggested that crosslinking is not homogeneous and that it is concentrated in the non‐crystalline domain. A correlation was found between the decrease in content of B‐type material and drug release kinetics. With increasing CLD, the reduction in crystalline order increases mobility, however, increasing covalent bonds in the excipient matrix reduces mobility. Differences in relaxation rate of the several overlapping resonances in the 70—80 ppm range of the 13 C spectrum are pronounced and allow tentative bond assignments.