Stability indicating RP-HPLC-UV method development and validation for estimation of Efinaconazole in bulk drug and pharmaceutical formulation

Efinaconazole is a potent triazole antifungal drug for the topical treatment of onychomycosis. In this comprehensive study, we developed a highly effective and reliable stability-indicating RP-HPLC (Reverse Phase High-Performance Liquid Chromatography) method, alongside two advanced UVspectrophotometric techniques—zero-order and first-order derivative methods for the accurate estimation of Efinaconazole. Employing the state-of-the-art Shimadzu model 1800 UV spectrophotometer, we ensured precision and reliability in our measurements. The chromatographic separation was expertly achieved on an Enable C18 column in isocratic mode, utilizing a carefully balanced mixture of methanol and 0.01 M potassium dihydrogen phosphate buffer (pH 5.5) in a 90:10 (v/v) ratio. This was conducted at a flow rate of 2 ml/min, with detection at 210 nm, ensuring optimal performance for our analysis. We rigorously subjected Efinaconazole to five distinct stress conditions, meticulously analyzing the resulting degradation products using the RP-HPLC technique. This allowed us to calculate their percentage recovery with high accuracy. The two UVspectrophotometric methods demonstrated exceptional linearity within the concentration range of 100-500 μg/ml, achieving peak performance with the zero-order method at 261 nm and the first-order derivative method at 270 nm, yielding correlation coefficients of 0.999 and 0.998, respectively. Remarkably, the average recoveries from our recovery studies ranged from 99.44% to 100.42% for the zero-order method and from 99.86% to 100.39% for the first-order derivative method, showcasing the methods' reliability and accuracy. For the RP-HPLC method, we established a linearity range of 25–125 μg/ml, achieving a strong correlation coefficient of 0.998. The retention time for Efinaconazole was consistently recorded at 4.55 min, with recovery rates impressively ranging between 99.8% and 100.08%. This comprehensive validation underscores the robustness and efficacy of our analytical methods for the accurate estimation of Efinaconazole in the treatment of onychomycosis.