ビタミンD_2散剤の安定性に関する研究(第7報) : 固体酸触媒によるビタミンD_2異性化の防止

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The effects of certain compounds which have the ability to reduce the surface acidity of excipients were examined in the isomerization of vitamin D_2 (D_2). Ethanolamines and polyoxyethylene (POE) compounds, such as polyethylene glycol 4000 (PEG), POE (20) stearate, or POE (23) lauryl ether, were used as stabilizers. The relationship between the acid strength of solid surfaces and the isomerization of D_2 was quantitatively examined in n-hexane solutions of D_2 in which natural aluminum silicate, CaHPO_4,or talc deactivated with PEG were suspended. The isomerization rates of D_2 decreased with increasing amount of PEG coated on the solids, and isomerization ceased when their acid strength had a pK_a 3.3. In powder preparations, D_2 isomerization was not observed when the excipient surfaces were reduced by the amines to a pK_a 4.8. For example, in a preparation with talc (pK_a⪈1.5) containing 0.5% D_2 and 0.1% BHA, the D_2 loss was 90% after a storage of 5 days at 37°, but only 8% after even 30 days with the addition of 1% triethanolamine. Coating agents, such as shellac, ethocel or celullose acetate phthalate, were unable to prevent D_2 isomerization.
社団法人日本薬学会の論文
1969-07-25