The purposes of the present invention are to provide a depot preparation which can form depots easily and can maintain the depot-formed state for a long period if desired and to provide a depot preparation which, when the depot preparation contains a drug, can release the drug sustainably over a long period after in vivo administration thereof. The present invention relates to a depot preparation containing a trialkyl citrate and/or an acetyltrialkyl citrate, wherein an alkyl group contained in the trialkyl citrate and an alkyl group contained in the acetyltrialkyl citrate are the same as or different from each other and each of the alkyl groups has 3 to 5 carbon atoms.本發明提供一種容易形成沈積物，且視需要亦可長時間維持沈積物狀態之緩釋劑；及提供一種於含有藥物之情形時，於投予至體內後長時間緩釋藥物之緩釋劑。本發明係關於一種緩釋劑，其含有檸檬酸三烷基酯及/或檸檬酸乙醯基三烷基酯，並且上述檸檬酸三烷基酯及上述檸檬酸乙醯基三烷基酯各自所具有之烷基相同或不同，且碳原子數為3~5。
