Introduction: Absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent ranges. Objective: Recently, studies are undertaken to design newer techniques for particle size enlargement such as spheronization, tumbling melt granulation, fluidized agglomeration, spherical crystallization etc. The basic aim of this project is to study and broaden the applications of spherical crystallization process, which not only enlarges the particle size but also changes the primary particle characteristics such as crystallinity, crystal form etc. Spherical crystallization, a novel particle design technique has been proved to improve the efficiency of the initial steps of the manufacturing operation. It combines the process of crystallization (design of primary particles) and agglomeration (design of secondary particles), and increases the added value of the product by endowing the primary and secondary particles with greater.Literature survey has revealed that, spherical crystallization has been attempted as an alternative to conventional granulation techniques to obtain the spherical agglomerates with improved tabletting properties but mainly for large dose drugs. The technique was also designed to sustain the drug release from the agglomerates (chlorpromazine hydrochloride), enhance process stability and economy (aspirin): In our laboratory, work on spherical crystallization was attempted by solvent change method for trimethoprim. The agglomerates obtained were evaluated for their tabulating properties. Result: Improvement and validation of two visible spectrophotometric methods applying BCG and DNFB as reagents for TMP determination in investigated formulations were successfully carried out. The near 100 % recoveries and low relative standard deviation values obtained, point to the suitability of the both modified and validated methods for determination of TMP in human and veterinary medicine. Discussion: It was concluded that the 1D spectroscopic method could be used for simultaneous determination of trimethoprim immediate-release oral dosage forms. This method could be used for the analysis of active pharmaceutical ingredients in dissolution studies and for quality control purposes. The method is rapid, simple, and economic without the need of high cost investment.