Validated Colorimetric methods for the determination of Tapentadol in bulk and its tablet dosage form

ABOUT AUTHOR
Iffath Rizwana¹, K. Vanitha Prakash²*, G. Krishna Mohan³, Juveria Samreen⁴,Saba Fatima^4
1Research Scholar, School of Pharmaceutical Sciences, JNTU-K, Kakinada, A.P. India
²Department of Pharmaceutical Analysis, SSJ College of Pharmacy, Hyderabad, A.P. India.
³Centre for Pharmaceutical Sciences, IST, JNTU Hyderabad, A.P. India.
⁴Deccan School of pharmacy, Nampally, Hyderabad, A.P. India

Abstract
Tapentadol (TAP) is a novel opioid pain reliever drug that is unusual in its possession of dual mechanism of action (mu opioid – receptor agonist and nor adrenaline reuptake inhibitor); this feature makes the active ingredient an attractive potential progenitor of a new pharmacological class. Two simple, rapid, sensitive and reproducible visible spectrophotometric methods were developed for the determination of Tapentadol HCl (TAP) in bulk and in its tablet dosage form. First method (M₁) employs formation of orange red colour complex by the reaction with bypyridyl in the presence of ferric chloride, which shows absorption maxima at 500 nm.  The second method (M₂) was based on the reaction of TAP with ferric ammonium sulphate-1, 10 phenanthroline that produces Red coloured complex, exhibits an absorption maximum at 617 nm. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 10-60 μg/ml for method M₁, and 10 – 80 μg/ml μg/ml for method M₂ respectively. Commercially available tablets were analyzed; the results obtained by the proposed methods were in good agreement with the labeled amounts. These methods offer the advantages of rapidity, simplicity, sensitivity and normal cost and can be easily applied to resource-poor settings without the need for expensive instrumentation and reagents.
Key words: Tapentadol, bypyridyl, phenanthroline, visible spectrophotometric.