Spectrophotometric Methods for the Determination of Ceftiofur and Tulathromycin in Bulk and Dosage Forms

Two simple, accurate and precise spectrophotometric methods were developed for the determination of two veterinary drugs, ceftiofur and tulathromycin in pure form as well as in pharmaceutical formulations. The first one (Method A) based on the reducing action of ceftiofur on Fe (ΙΙΙ) to Fe (ΙΙ) in its complex with 1, 10- phenanthroline (ferrin complex) to give the orange-red colored ferroin complex that exhibits an absorption maximum at 511 nm. Ceftiofur exhibited good linearity in the concentration range of 0.3-3.0 μg mL−1.The second method (Method B) depended on formation of a binary complex between tulathromycin and eosin Y in in the presence of carboxy methylcellulose as surfactant. Under the optimum conditions, the binary complex showed absorption maxima at 556 nm. The method obeyed Beer’s law over concentration range of 1.0–15.0 μg mL−1. The proposed methods were used for determination of the studied drugs in pharmaceutical formulation; maxfur® powder and draxxin® injections with mean recoveries of 99.57and 99.71%, respectively. The validity of the methods was further proved by applying the standard addition technique. A proposal of the reactions pathways were described.