The objective of the present work is to develop simple, precise and accurate colorimetric methods for the estimation of Gliclazide (Method A), Nortriptyline (Method B), Cilnidipine (Method C) using MBTH (3-Methyl-2-Benzothiaazide Hydrazine) reagent. All the three Methods were developed on Perkin Elmer LAMBDA 25 UV/VIS spectrophotometer with 1cm quartz cells. Quantification of Gliclazide, Nortriptyline, Cilnidipine were done by Oxidative coupling method using MBTH as reagent. Gliclazide (Method A), Nortriptyline (Method B) and Cilnidipine (Method C) undergoes oxidation with ferric chloride and couples with MBTH. The coupled oxidant shows maximum absorbance measured at 660 nm for Gliclazide (Method A), 650 nm for Nortriptyline (Method B), and 600 nm for Cilnidipine (Method C). The colorimetric method was extensively validated as per ICH guidelines and all the parameters were within the acceptance criteria with correlation of 0.999% RSD less than 2 for the method. The method was proved to be more accurate, simple, precise and rapid by statistical validation as well as recovery studies and can be used for routine laboratory analysis.