摘 要 目的：研究强的松、强的松龙在10名男性健康志愿者血浆及血中有核细胞内的可逆代谢药代动力学。方法：各受试者按随机交叉设计进行三次试验，分别为：(1)不服用药物；(2)单次口服50mg强的松；(3)单次口服50mg强的松龙。从血样中分离出血浆和有核细胞后用HPLC法测定强的松、强的松龙和可的松的浓度。结果：口服强的松后，血浆中强的松和强的松龙的峰浓度(Cmax)分别为43.0±11.8和443.8±198.3mg·L^-1，曲线下面积(AUC)分别为 382±127和2823±943mg·h·L^-1。口服强的松龙后，血浆中强的松和强的松龙的Cmax分别为47.2±14.0和538.9±92.4mg·L^-1，AUC分别为335±120和3664±1170mg·h·L^-1。两次给药后的强的松与强的松龙的AUC比值经统计比较有显著差异(口服强的松时为7.44±0.64，口服强的松龙时为11.01±0.57，P＜0.01)。其余药代动力学参数如表观分布容积(Vd)、清除率(CL)和消除半衰期(T1/2)按照可逆代谢非房室模型进行计算，结果表明强的松的可逆代谢和其他消除过程均比强的松龙快。强的松与强的松龙相互转化的循环分数(RF)为0.68 ± 0.08，口服强的松后，血中有核细胞内强的松和强的松龙的Cmax分别为0.90±0.27和8.93±1.78mg·10-9细胞，而口服强的松龙时，相应的Cmax分别为0.83±0.32和9.26±3.71mg·10-9细胞。血中有核细胞内浓度与血浆浓度间存在显著的相关性，提示强的松和强的松龙通过被动扩散方式转运至细胞内。结果还显示细胞内强的松龙的T1/2（口服强的松和强的松龙时分别为2.11±0.67和2.57±0.35 h）明显比细胞内强的松的T1/2（口服强的松和强的松龙时分别为4.28±1.03和4.20±0.95 h）及血浆中强的松龙的T1/2（5.31±2.26 h）要短(P＜0.01)，结论：强的松和强的松龙间的相互转化是一种非线性过程且是人体内最主要的消除过程。此外，强的松龙在细胞内的药代动力学与血浆并不完全一致。

Reversible Metabolic Pharmacokinetics of Prednisone and Prednisolone in Plasma and Blood Nucleated Cells in Healthy Volunteers

WANG Jian-Hua,ZHAO Xiang-Lan

(Department of Clinical Pharmacology, Sun Yat-sen University of Medical Sciences, Guangzhou 510080)

Abstract OBJECTIVE: To investigate reversible metabolic pharmacokinetics of prednisone and prednisolone in plasma and blood nucleated cells in 10 healthy male volunteers. METHODS: Each subject participated in a three-phase randomed crossover study. The three phases were (1) no drug administration, (2) oral administration of a single 50-mg prednisone, and (3) oral administration of a single 50-mg prednisolone. The plasma and nucleated cells were separated from blood for HPLC analysis of prednisone, prednisolone and cortisol. RESULTS: After administration of prednisone, The maximum plasma concentrations (Cmax) of prednisone and prednisolone were 43.0±11.8 and 443.8±198.3 mg.L^-1, respectively. The areas under concentration-time curve (AUC) of prednisone and prednisolone were 382±127 and 2823±943mg.h.L^-1, respectively. After administration of prednisolone, The Cmax of prednisone and prednisolone were 47.2±14.0 and 538.9 ±92.4mg.L^-1, respectively. The AUC of prednisone and prednisolone were 335±120 and 3664±1170mg.h.L^-1, respectively. There were statistically significant differences in AUC ratio of prednisolone to prednisone for both doses (7.44±0.64 vs. 11.01±0.57, P ＜ 0.01). Other pharmacokinetic parameters, such as volume of distribution (Vd), clearance (CL), elimination half-life (T1/2), were calculated according to a reversible metabolic non-compartment model. It appears from these parameter values that the reversible metabolism and other eliminations of prednisone are faster than those of prednisolone. The fraction recycled through interconversion (RF) was 0.68±0.08, After administration of prednisone, the Cmax of prednisone and prednisolone in blood nucleated cells were 0.90±0.27 and 8.93±1.78 mg.10-9 cells, respectively. After administration of prednisolone, the Cmax of prednisone and prednisolone in cells were 0.83±0.32 and 9.26±3.71mg.10-9 cells, respectively. There was a significant correlation between plasma concentrations and blood nucleated cells concentrations, which suggested prednisone and prednisolone transfer into cells by passive diffusion. The of prednisolone in cells (2.11±0.67 and 2.57±0.35 h, after administration of prednisone and prednisolone respectively) were significantly (P＜ 0.01) shorter than either of prednisone in cells (4.28±1.03 and 4.20±0.95 h, after administration of prednisone and prednisolone respectively) or of prednisolone in plasma (5.31±2.26 h). CONCLUSION: The interconversion between prednisone and prednisolone might be a nonlinear process and it is the most primary elimination process in human as well. The pharmacokinetics of prednisolone in cells is not fully consistent with that in plasma.

Key words prednisone; prednisolone; reversible metabolism; pharmacokinetics; blood nucleated cells

强的松(prednisone, PDN)、强的松龙(prednisolone, PSL)是临床上最常使用的糖皮质激素之一。动物研究已经证实，二者的药代动力学具有两个基本特性，即剂量依赖性和可逆代谢^[1]。强的松龙是目前已知活性最强的皮质激素之一，而强的松在体外基本无活性，需要在体内转化为强的松龙而发挥作用，同时强的松龙也可以可逆代谢为强的松。其剂量依赖药代动力学部分归因于它们在血浆和组织中的非线性蛋白结合，但更重要的是它们具有一系列非线性的代谢消除过程^[2]。强的松和强的松龙的这些复杂体内过程给其药代动力学研究带来不少困难，故目前国内外这方面的研究还主要停留在动物实验上，在人体内的研究还不多见。糖皮质激素主要通过与细胞浆内的糖皮质激素受体结合并进一步转运至细胞核内而产生作用，其作用强度由受体的亲和力及受体部位的游离激素水平决定，而后者又受许多药代动力学因素的影响^[3]。为此我们选择10名健康志愿者作研究对象，同时检测血浆及血中有核细胞强的松、强的松龙的浓度并对其药代动力学特性加以研究，为今后进一步开展临床病理状态下糖皮质激素的药代与药效动力学研究打下基础。

材 料 与 方 法

1. 研究对象

男性健康受试者10名，年龄28.7±3.5岁，身高170.6 ±4.5 cm，体重65.4±6.3 kg。各受试者实验前两周未使用过任何药物，经体检肝肾功能正常，签署书面知情同意书。

2. 试验药品

醋酸强的松片，广东开平侨光联合制药厂产品，每片5mg，批号920318；醋酸强的松龙片，上海信宜药厂产品，每片5mg，批号880614。

3. 实验设计

试验共分三次进行。第一次试验各受试者均不服用药物，仅采样观测基础可的松水平。第二、三次为服药试验，将10名受试者随机分为两组，按交叉设计分别单剂量口服醋酸强的松或醋酸强的松龙片共50 mg (实际相当于强的松或强的松龙44.5 mg)。为避免皮质激素时辰药理对试验结果的影响，各次试验均统一于上午8:30开始。试验当天早晨各受试者空腹，午、晚餐进统一膳食，不得服用任何其他药物，忌烟酒。试验开始后0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 11和14 h从臂静脉留置针（内含肝素抗凝）内分别抽取静脉血5 ml。

4. 样本处理与检测

各时间点血样随即离心分离出血浆，置-35℃冰箱中贮存备用。分离血浆后的剩余部分加入约8ml预冷至4℃的红细胞溶解液（含NH4Cl 155 mmol·L^-1，KHCO3 10 mmol·L^-1和EDTA-2Na 0.1 mmol·L^-1），摇匀后放置。沉淀的细胞再反复用上述溶解液洗吹至不含血红素等有色物质，离心得到白色的细胞沉淀物。准确加入3～8 ml预冷至4 ℃的细胞混悬液（50 mmol·L^-1磷酸盐缓冲液，pH 7.4）使细胞重新混悬，在显微镜下进行有核细胞计数后用超声波细胞破碎仪制成有核细胞液样本，置-35℃冰箱中贮存至测定。

取血浆0.5 ml或有核细胞液2 ml（每毫升细胞液约含106～107个细胞）用于强的松和强的松龙的浓度测定。采用本实验室建立的可同时检测生物样本中强的松、强的松龙、可的松和氢化可的松浓度的反相HPLC法（另文发表）。该方法对各组分的血浆最低检测浓度约为2mg·L^-1，细胞液最低检测浓度约为0.5mg·L^-1。平均提取回收率均在80%以上，天内和天间变异系数大多在10%以内。

5. 药代动力学分析

强的松和强的松龙在体内进行可逆代谢转化，需同时具有口服强的松和强的松龙后血浆中强的松和强的松龙的浓度数据才能进行药代动力学分<