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KMID : 0369819970270020099
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Jorunal of Korean Pharmaceutical Sciences
1997 Volume.27 No. 2 p.99 ~ p.108
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Enzymatic Degradation and Stabilization of Thyrotropin Releasing Hormone in Various Rabbit Mucosa Extracts
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전인구/Chun IK
신동원/Shin DW
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Abstract
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To evaluate the feasibility of mucosal delivery of thyrotropin releasing hormone (TRH) through various mucosae, enzymatic degradation and stabilization of TRH in the nasal, rectal and duodenal extracts of rabbits were studied. TRH in the extracts was assayed by HPLC and its degradation was found to follow apparent first-order kinetics. The residual concentrations of TRH in the mucosal extracts of nasal, rectal and duodenal segments after 24 hr of incubation were found to be 65.1(±1.1),19.7(±2.7) and 0%, and in the serosal extracts, 65.6(±5.5),75.2(±1.1) and 68.7(±1.4), respectively. This result suggests that there is a significant difference in the activity of TRH-degrading enzymes among the sites of administration. The inhibition of TRH degradation in the mucosa extracts was kinetically investigated using various additives such as thimerosal, benzalkonium chloride, disodium edetate, σ?phenanthroline, dithiothreitol and dithioerythritol, and IC50 values of inhibitors were calculated. The results obtained showed that thimerosal (0.5 mM) and benzalkonium chloride (0.141 mM) protected TRH from the enzymatic degradation in all the mucosa extracts more than 95% after 24 hr of incubation.
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KEYWORD
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Thyrotropin releasing hormone, Mucosa extracts, Enzymatic degradation, Enzyme inhibitor, Stabilization
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