Meropenem is a relatively unstable compound when dissolved; therefore, in studying pharmacokinetics (PK), accurate PK analysis may be interrupted depending on the handling of collected blood samples because it also rapidly degrades during processing and preserving of the blood samples. Thus, prior to PK studies, we determined the stability of meropenem in plasma samples and evaluated the optimal preservation method. Plasma samples including meropenem with and without the same volume of 1 M

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... morpholino)-propane-sulfonic acid (MOPS) buffer as a stabilizer were preserved under the conditions of -80℃, -20℃, 4℃ and 25℃, and the remaining meropenem level upon high-performance liquid chromatography at 1, 3, 7, 14, 30, 60, 120 and 180 days following preservation was measured to calculate the meropenem residual rate. The residual rate of plasma samples preserved at -80℃ was 95% or higher for 180 days. On the other hand, under the preservation condition over -20℃, the residual rate at 1 day following preservation was less than 95%. The stability of plasma sample was improved by adding MOPS buffer, and the residual rate was 95% or higher for 7 days at -20℃. Therefore, plasma samples for PK study of meropenem should be added MOPS buffer and preserved in a frozen state.