Validation and stability indicating RP-HPLC method for the determination of tadalafil API in pharmaceutical formulations

B. Prasanna Reddy¹*, K. Amarnadh Reddy² and M. S. Reddy³

¹Department of Quality control, Nosch Labs Pvt Ltd, Hyderabad-500072, A.P, India.

²Department of AR and D, Aurigene Discovery Technologies Ltd, Bangalore, India.

³Department of Plant Pathology and Entomology, Auburn University, USA.

*Corresponding author. E-mail: drbpkreddy@gmail.com. Tel: +91-9848392677.

Accepted 4 January, 2010

   Abstract

The present study describes the development and subsequent of a stability indicating RP-HPLC method for the analysis of tadalafil. The samples separated on an Inertsil C₁₈, (5 m , 150 mm x 4.6 mm i.d) by isocratic run using acetonitrile and phosphate buffer as mobile phase), with a flow rate of 0.8 ml/min, and the determination wavelength was 260 nm for analysis of tadalafil. The described method was linear within range of 70 - 130 µg/ml (r² = 0.999). The precision, ruggedness and robustness values were also within the prescribed limits (< 1% for system precision and < 2% for other parameters). Tadalafil was exposed to acidic, basic, oxidative and thermal stress conditions and the stressed samples were analyzed by the proposed method. Chromatographic peak purity results indicated the absence of co-eluting peaks with the main peak of tadalafil, which demonstrated the specificity of assay method for estimation of tadalafil in presence of degradation products. The proposed method can be used for routine analysis of tadalafil in quality control laboratories.

Key words: RP-HPLC, tadalafil, validation, stability indicating assay, forced degradation.