A rapid assay procedure for triamcinolone in tablets was described which enabled a sensitive determination of triamcinolone in tablets in less than one fifth time-consuming than official USP method to give identical result. Triamcinolone in tablets was dissolved and extracted with N,N-dimethylformamide rapidly followed by methanol and chloroform dilution tO 5 mcg per ml. The colorimetric determination after Zaffar-oni reaction of α-ketol side chain was carried out at triamcinolone con-centration 3 mcg per ml. The mechanism of solvent effect in Zaffaroni reaction was also discussed. It was revealed that the rate of reaction was accelerated by solvents of low interna1 pressure.In practical sense,the addition of chloroform or ethyl ether in the reaction media would facilitate instant color production at room temperature due to the redu-ction of the solubility parameter difference between Solvent and the activated complex. The method was applicable to most of water insoluble α-ketol corticoids in solid preparations and was valuable in in-process and off-process uniformjty control. USP及BPC皆使用乙醇為溶媒，利用機械振盪二小時抽出錠劑粉未內之Triamcinolone.USP更在標準液之泡製上完全使用氯仿。實際上， Triamcinolone在乙醇及氯仿中之溶解度極小，且溶解速度極慢，不但操作費時，且易因抽出程度之差異，難獲得穩定之定量結果。日本藥局方並不收載Triamcinolone錠劑，但對原料之定量採用甲醇為溶媒，雖比乙醇及氯仿為佳，但未能顯著地縮短操作時間，而且日本藥局方使用UV吸光度之測定，靈敏度遠較USP及BPC之呈色法為低。像Tria-mcinolone一類製劑，因劑量微少，須嚴格要求均勻度，必須在生產過程中加以經常性的檢定。為建立快速，靈敏之定量方法，以利生產中之品管須要，本研究檢討Triamcinolone在各種溶媒中之溶解度及溶解速度，發現N,N-dimethylformamide及N,N-d imethylacetamide為Triamcinolone最優異之溶媒。利用N,N-d imethylformamide溶出Triamcinolone經甲醇及氯仿之稀釋，在鹹性液中和Tetrazolium blue進行Zaffaroni反應呈色，則Triamcinolone可在 3 mcg/ml之低濃度下被正確之定量。氯仿之存在對Zaffaroni呈色反應極為重要，若不添加氯仿於測定液中，則在室溫下，不能呈色。經檢討Zaffaroni反應中各種溶媒的效應，發現降低反應液之內壓( internal pressure)能加速Zaffaroni反應。在實用上， Chloroform，及Ethyl ether皆可應用於反應系中，扮演即刻呈色作用劑，縮短操作時間。使用N,N-dimethylformamide之快速溶出法所得之溶液，不適於利用UV吸光度測定法，因為此溶媒在238 nm處，有吸光性會干擾測定結果，造成誤差。但若使用Zaffaroni呈色法則可獲得和USP法定方法同樣正確之結果而且快速五倍以上。本法可通用於非水溶α-ketol corticoids固體製劑之定量。
