Green potentiometric method for determination of sildenafil citrate in pharmaceutical dosage forms

Abstract

Background: The main challenge of the pharmaceutical industry in the last years is to implement eco-friendly methods in quality control of medicines based on the principles of green analytical chemistry. In this study, green analytical method for potentiometric titration of sildenafil citrate (SC) in film-coated tablets was optimized and validated. Materials and Methods: The quantitative determination of sildenafil citrate in film-coated tablets, dissolved in 50 mL 1% (v/v) Polysorbate 80 solution, was performed using potentiometric titration with 0.1 M sodium hydroxide. Validation of the method included linear regression analysis based on eleven different quantities of the sildenafil citrate, active substance and determination of specificity, precision and accuracy in accordance with ICH guideline. Results: The use of polysorbate 80 as a solubilization agent enabled elimination of the toxic organic solvents needed for non-aqueous potentiometric titration of active pharmaceutical ingredients with low solubility. The obtained results from method validation study confirm the linearity of the method. Statistical evaluation of the data obtained from regression analysis confirm that the method is acceptable for determination of the content of SC in API. The recovery values (98.0 % - 102.0 %), the obtained results for the relative standard deviation (below 0.5%) and F test confirm the accuracy and precision of the method. The results obtained from the method validation study comply to the defined acceptance criteria, confirming the applicability of the proposed method. Conclusion: The proposed method is applicable for determination of the content of SC in raw material, as well as in finished product (tablets). The method implements the principles of green analytical chemistry, providing one possible approach for overcoming the challenges of the pharmaceutical industry for transfer of non-green methods used in quality control into green and environment friendly methods.