Donnelly J G, Soldin S J
Department of Pharmacology, George Washington University Medical Center, Washington, D.C.
Ther Drug Monit. 1989 Nov;11(6):696-700. doi: 10.1097/00007691-198911000-00015.
Cyclosporine A (CsA) is extensively metabolized in the liver. Some of the known metabolites share immunosuppressive properties with the parent drug. Furthermore, CsA therapy is used in an increasing number of clinical conditions, some of which affect the pharmacokinetics of the drug. At this time, it is not yet known if CsA or its metabolites are responsible for the nephrotoxicity or hepatotoxicity observed in some individuals. Some high-performance liquid chromatography (HPLC) and monoclonal immunoassay procedures measure parent drug and not the pharmacologically active metabolites, while polyclonal immunoassays and nonspecific monoclonal antibody immunoassays measure both parent drug and metabolites. However, it is unlikely that the degree of cross-reactivity with metabolites correlates with their immunosuppressive effect. To overcome these drawbacks, we have developed a method of measuring CsA activity in whole blood using specific receptors from the cytosol of human mononuclear leukocytes that have been semipurified through ultracentrifugation. The basis of the procedure is the competitive binding at specific receptor(s) between a constant concentration of [3H]dihydrocyclosporine and the variable concentrations of cyclosporine and its pharmacologically active metabolites in whole blood. Comparisons between six different assays (three specific, two nonspecific, and the receptor assay) were made. Overall, the two specific radioimmunoassay procedures correlated well to HPLC, while correlation of the two nonspecific immunoassay procedures to HPLC was poor. Poor correlation was also found to exist between the radioreceptor assay and the nonspecific assays, indicating that the cytosolic binding of CsA and its metabolites cannot be correlated to currently available assays.
环孢素A（CsA）在肝脏中被广泛代谢。一些已知的代谢产物与母体药物具有相同的免疫抑制特性。此外，CsA疗法在越来越多的临床病症中得到应用，其中一些病症会影响该药物的药代动力学。目前，尚不清楚CsA或其代谢产物是否是某些个体中观察到的肾毒性或肝毒性的原因。一些高效液相色谱法（HPLC）和单克隆免疫测定方法测量的是母体药物而非具有药理活性的代谢产物，而多克隆免疫测定和非特异性单克隆抗体免疫测定则同时测量母体药物和代谢产物。然而，与代谢产物的交叉反应程度不太可能与其免疫抑制作用相关。为克服这些缺点，我们开发了一种使用来自人单核白细胞胞质溶胶的特异性受体来测量全血中CsA活性的方法，这些受体已通过超速离心进行了半纯化。该方法的基础是在特定受体处，恒定浓度的[3H]二氢环孢素与全血中不同浓度的环孢素及其药理活性代谢产物之间的竞争性结合。我们对六种不同的测定方法（三种特异性方法、两种非特异性方法和受体测定法）进行了比较。总体而言，两种特异性放射免疫测定方法与HPLC的相关性良好，而两种非特异性免疫测定方法与HPLC的相关性较差。放射受体测定法与非特异性测定法之间也存在较差的相关性，这表明CsA及其代谢产物的胞质结合与目前可用的测定方法无关。
