This study aims was simultaneous identified and quantified, used a HPLC method, eight active pharmaceutical ingredients, Cyanocobalamin (Vitamine B12), Benzyl alcohol, Chloramphenicol, Prednisolone, Tylosin A, Tylosin B, Tylosin C and Tylosin D. In a very short time, and with very low cost, all eight compounds was separated and quantified used this HPLC method (UV-VIS detection). The method is enough sensitive to quantified and monitorised related substances/degradation product according to VICH GL 11(R). The method can be easily applied in any analytical laboratory, because it uses common reagents, a chromatographic column frequently used, octadecylsilylsilicagel (C18) and common equipments in pharma laboratories (HPLC, multiwavelengths UV-VIS detection).