Experimental design in chromatographic analysis of pramipexole and its impurities

Abstract

Pramipexole is a dopamine D2-agonist/antiparkinsonian agent in which BI-II 546 CL, BI-II 751 xx and 2-amino benzothiazole are commonly found as impurities. Due to the lack of analytical data on pramipexole and its related substances in bulk drug and pharmaceuticals, we aim at the optimization and characterisation of the chromatographic behaviour of pramipexole and its related substances employing experimental design. The analysis was performed using a C18 column with mobile phases containing different ratios of acetonitrile and water phase (aqueous triethylamine/ortophosporic acid). The detection was performed at 262 nm for pramipexole, BI-II 751 xx and 2-aminobenzthiazole and at 326 nm for BI-II 546 CL. To define the influence of chromatographic parameters on separation, a central composite design was chosen. The content of acetonitrile, TEA and pH of the water phase were identified as the factors with important influences on retention. Using an appropriate mathematical model, we were able to predict retention under different conditions.