Lynn A G, Bennett G W
Analysis Department, Reckitt and Colman plc, Hull, UK.
J Pharm Biomed Anal. 1991;9(1):9-18. doi: 10.1016/0731-7085(91)80230-7.
The recent interest in RX77368 for the treatment of Motor Neurone Disease (MND) has led to the requirement for an assay (RIA) capable of detecting the peptide at low levels in plasma. Several drug conjugates were prepared in which RX77368 was covalently linked to larger proteins, e.g. bovine serum albumin, keyhole limpet haemocyanin or bovine thyroglobulin, the best yield being obtained with the bis-diazotized benzidine reaction (BDB) linking RX77368 to KLH. The latter conjugate was injected into sheep and ultimately produced an antibody of sufficiently high titre to be used. This combined with an iodinated radiolabel formed the basis of the radioimmunoassay. Cross-reactivity studies using similar analogues and RX77368 metabolites showed that the antibody was specific for RX77368. The greatest cross-reactivity was exhibited by the pGlu-His-monomethylProNH2 peptide (RX74355), but, not being a natural metabolite, this did not interfere with the assay. The RIA was used to measure RX77368 in MND patients in a recent clinical study, where RX77368 was administered both by the intravenous and oral routes. High plasma concentrations of RX77368 were found in the patients given intravenous drug by infusion. The oral route exhibited much lower levels, but had a sustained duration of action of up to 12 h.
最近对RX77368用于治疗运动神经元病（MND）的关注，引发了对一种能够检测血浆中低水平该肽的检测方法（放射免疫分析，RIA）的需求。制备了几种药物缀合物，其中RX77368与较大的蛋白质共价连接，例如牛血清白蛋白、钥孔戚血蓝蛋白或牛甲状腺球蛋白，通过双偶氮化联苯胺反应（BDB）将RX77368与KLH连接可获得最佳产率。将后一种缀合物注射到绵羊体内，最终产生了效价足够高的可用抗体。这与碘化放射性标记物相结合构成了放射免疫分析的基础。使用类似类似物和RX77368代谢物进行的交叉反应研究表明，该抗体对RX77368具有特异性。pGlu-His-单甲基ProNH2肽（RX74355）表现出最大的交叉反应性，但由于它不是天然代谢物，因此不会干扰该检测。在最近一项临床研究中，该放射免疫分析被用于测量MND患者体内的RX77368，在该研究中，RX77368通过静脉和口服途径给药。通过静脉输注给药的患者血浆中发现了高浓度的RX77368。口服途径的血药浓度低得多，但作用持续时间长达12小时。
