Purpose: To develop a simple, rapid and selective method for the spectrophotometric determination of cefadroxil and ceftriaxone using 1, 2-napthaquinone-4-sulfonic acid sodium. Methods: The method was based on the derivatization of cefadroxil and ceftriaxone with 1, 2naphthaquinone-4-sulfonic acid sodium in alkaline medium to yield orange-colored products. Results: The reaction products of cefadroxil and ceftriaxone at their respective λ max of 475 and 480 nm showed linearity in the

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... n range of 10 -100 and 25 -175 µg/ml, respectively. Relative standard deviations of 0.82 % for cefadroxil and 0.95 % for ceftriaxone were obtained. Recoveries of cefadroxil tablets and ceftriaxone injection were in the range of 100.66 ± 0.98 and 99.38 ± 0.84 %, respectively. Conclusion: Recovery studies gave satisfactory results indicating that none of the major additives/excipients interfered with the assay method. Therefore, the proposed method is simple, rapid, precise and convenient for the assay of cefadroxil and ceftriaxone in commercial preparations.