Assay of Tolterodine Tartrate in Bulk and Capsule Formulations by using Simple and Affordable Visible Spectrophotometric Methods

Two simple, sensitive and affordable visible spectrophotometric methods (M₁ and M₂) have been developed for the estimation of tolterodine tartrate (TT) in bulk and dosage forms. Method M₁ involves Internal salt formation of aconitic anhydride, dehydration product of citric acid [CIA] with acetic anhydride [Ac₂O] to form colored chromogen with an absorption maximum of 565 nm and the method M₂ is based on the formation of green colored coordination complex by the drug with cobalt thiocyanate which is quantitatively extractable into nitro benzene with an absorption maximum of 625 nm. Beer ’s law obeyed in the concentration range of 8–24 μg/ml for method M₁ and 16–48 μg/ml for method M₂. Commercial available capsules were analyzed and the results are statistically compared with those obtained by the reference UV method and validated by recovery studies. The results are found satisfactory and reproducible. These methods are applied successfully for the estimation of the tolterodine tartrate in the presence of other ingredients that are usually present in dosage forms. These methods offer the advantages of rapidity, simplicity and sensitivity and normal cost and can be easily applied to resource-poor settings without the need for expensive instrumentation and reagents.