Drug manufacturing control requires high level and intensive analytical and chemical support of all stages to ensure the drug's quality and safety. Highly specific and sensitive analytical techniques hold the key to the design, development, standardization and quality control of medicinal products. The book is focussed on development and validation of RP-HPLC method for simultaneous estimation of bromhexine HCl, dextromethorphan HBr, and guaiphenesin, colorimetric method for estimation of ferrous fumarate and zinc sulphate, and UV spectrophotometric method for simultaneous estimation of ambroxol HCl, cetirizine HCl, and dextromethorphan HBr, form their combined dosage form. The analysis should be useful to some pharmaceutical companies, students of pharmacy field or anyone else seeking knowledge in the respective field.