Novel spectrophotometric methods for concurrent assessment of duloxetine and avanafil in their binary mixture using derivative spectroscopy: greenness-blueness evaluation

Antidepressant drugs, particularly selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are known to induce sexual dysfunction as a side effect. Duloxetine (DLX) and Avanafil (AVN) are simultaneously determined in their pure state and laboratory-prepared mixtures by two novel, environmentally friendly spectrophotometric methods. The first method was based on second order derivatives while the second method is based on first derivative dual-wavelength. In method I, the linearity range was found to be 0.5–12 µg/mL and 1–12 µg/mL with limit of detection 0.15 µg/mL and 0.27 µg/mL for DLX and AVN, respectively. In method II, the linearity range was found to be 1–10 µg/mL for both drugs with limit of detection 0.18 µg/mL and 0.21 µg/mL for DLX and AVN, respectively. The validation of these approaches meets the International Council for Harmonization’s (ICH) standards. Furthermore, three current ecological tools namely the Eco-Scale, GAPI, and AGREE were used to evaluate the proposed method’s greenness. The sustainability characteristics of the proposed method were also assessed using the Blue Applicability Grade Index (BAGI), a recently developed metric for assessing the practicality (blueness) of procedures.