Simultaneous determination of sulpiride and mebeverine by HPLC method using fluorescence detection: application to real human plasma

Mebeverine hydrochloride (MEB) 3,4-Dimethoxybenzoic acid 4- [ethyl[2-(4-methoxyphenyl)-1-methylethyl]amino]-butylester (Figure 1) is a potent direct antispasmodic acting mainly on the smooth muscles of the gastrointestinal tract and particularly effective against the colonic spasm [1].Mebeverine undergoes rapid and extensive presystemic (first-pass) hydrolysis in the gut and/or the liver into mebeverine alcohol and veratic acid [1].British Pharmacopoeia described a non aqueous titrimetric method for determination of MEB in pure form [2].Sulpiride (SUL) 5-(Aminosulfonyl)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-2-methoxy-benzamide (Figure 1) is the most widely prescribed anti-psychotic drug. It is a selective dopamine D2 antagonist with antidepressant activities it exerts a mood elevating effect and antiemetic action [1].Regarding SUL, British Pharmacopoeia described a non aqeous titrimetric method for determination of SUL in pure form [2].Combination of MEB and SUL is used for treatment gastrointestinal and colic spasms which are a consequence of psychosomatic manifestation of nervous tention, mental stress or anxiety. MEB and SUL were determined in their binary mixture via derivative spectroscopy [3,4], first derivative synchronous fluorescence spectroscopy [5]. TLC- densitometry [4], HPLC [4-6] and chemometric techniques [7].The aim of the present study is to establish and develop a novel, sensitive and selective HPLC method for simultaneous determination of MEB and SUL either per se or in pharmaceutical preparations and in real human plasma as SUL and MEB metabolite (veratic acid). However, to the best of our knowledge, no analytical methods have been reported for the simultaneous determination of all compounds in the presence of their impurities and degradation products, which might interfere with the analysis of the active ingredients- HPLC experiments were performed with a Merck Hitachi L- 7100 chromatograph equipped with a Rheodyne injector valve with a 20 μL loop.