Page 1 Simultaneous determination of albendazole and praziquantel in rat plasma by HPLC-UV Shreya Shah 2 , Suddhasattya Dey 1* , Kamal Kant 1 , Padma Charan Behera 1 and Manik Ghosh 1* 1 Birla Institute of Technology, Mesra, Ranchi, Jharkhand (835215), India 2 Sigma Institute of Pharmacy, Vadodara, Gujarat (390016), India Email: manik@bitmesra.ac.in Abstract A simple, sensitive, and easy high-performance liquid chromatographic [HPLC] method has been developed and validated for the simultaneous estimation of albendazole [ABZ] and praziquantel [PRQ] using diazepam as an internal standard in rat plasma. Extraction of ABZ, PRQ and Diazepam in rat plasma was carried out by a process which involves precipitation of proteins called protein precipitation. Protein precipitation method was done by using 8.25% perchloric acid. Chromatographic separations were performed using an Enable C18 column [250 mm × 4.6 mm, 5 μm: Spinco Biotech Pvt. Ltd]. The mobile phase consisted of acetonitrile: water [60:40, V/V] at a flow rate of 1.0 mL min-1 at an ambient temperature for plasma samples. The above method was developed and validated over the range from 50-8000 ng/mL for both ABZ and PRQ in the rat plasma. The recovery of ABZ was found to be 97.81 to 105.28%, whereas PRQ recoveries ranged from 96.80 to 102.63% in the rat plasma. Acceptable Intra- and inter-day assay precision [<15% R.S.D.] and accuracy [<15% R.S.D.] were observed over 50–8000 ng/mL for ABZ and PRQ in rat plasma. This method can be effectively applied to the pharmacokinetic study of albendazole and praziquantel in rat plasma to determine all the pharmacokinetic parameters. Keywords: Albendazole; Praziquantel; Validation; Bioanalytical; HPLC 1. INTRODUCTION The most common helminthic disease of the nervous system is nee is the most common helminthic disease of the nervous system, is neurocysticercosis, which is considered as a serious public health problem in developing countries of Latin America, Asia and Africa [1- 3]. The use of both the drugs Albendazole [ABZ] and Praziquantel [PRQ] consider an effective against the cystic larvae for the treatment of neurocysticercosis over the last 20 years with the use of both the drugs ABZ & PRQ. ABZ has been found an effective drug of choice than PRQ, but this persistence of cysts even after continuous use of ABZ [2]. For the patients, who were the persistence of cyst after the use of ABZ, an alternative treatment therapy was developed where there was simultaneous use of PRQ and ABZ has been evaluated [4-5]. Albendazole and Praziquantel in combination were used extensively for human hydatid disease [6-9]. Albendazole [ABZ] is an inactive moiety but it readily gets metabolized to an active metabolite Albendazole sulfoxide [ABZSO] then this ABZSO is then further metabolized to an inactive metabolite Albendazole sulfone [ABZSO2] [10]. As ABZ is metabolized extensively, therefore, the plasma concentration of ABZ is also very low as a result the pharmacokinetic studies were been done using Albendazole sulfoxide [ABZSO] as an active metabolite and Albendazole sulfone [ABZSO2] as an inactive metabolite [11-15]. Metabolism of Praziquantel [PRQ] occurs giving a number of hydroxylated metabolites [16-18], among which the active metabolite is mainly trans-4- hydroxypraziquantel [TRANS], an active metabolite [19]. Evaluation and the determination of various pharmacokinetic parameters of ABZ and PRQ, the method has been developed