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The solid-state stability of amorphous quinapril in the presence of β-cyclodextrins

✍ Scribed by Jinjiang Li; Yushen Guo; George Zografi

Publisher
John Wiley and Sons
Year
2002
Tongue
English
Weight
297 KB
Volume
91
Category
Article
ISSN
0022-3549

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✦ Synopsis

The major objective of this study was to investigate the effects of bcyclodextrin (b-CD) and hydroxypropyl-b-cyclodextrin (HP±b-CD) on the solid-state chemical reactivity of the drug, quinapril, when amorphous samples are prepared by colyophilization of quinapril and each of these b-CDs. For comparison, a physical mixture with b-CD and colyophilized mixtures with trehalose and dextran were also prepared and subjected to a similar chemical stability test at 808C followed by HPLC analysis. Signi®cant inhibition of degradation was observed only for colyophilized miscible mixtures with b-CD and HP±b-CD at molar ratios in excess of 1:1. Colyophilized mixtures with trehalose and dextran, shown to have phase separated, and the physical mixture with b-CD exhibited no inhibiting effects. This suggests that speci®c molecular complexation is responsible for the signi®cant inhibition by the b-CDs. The tendency of quinapril to form molecular complexes in solution with the b-CDs was measured by 1 H solution NMR, by estimating complexation constants from the chemical shift of speci®c groups on quinapril. Supporting evidence for solid-state complexation was provided by FTIR analysis. DSC and TSC measurements indicated that the b-CDs do not have high enough glass transition temperatures to reduce reactivity by reducing molecular mobility.

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