Development of Novel RP-HPLC Method for Separation and Estimation of Critical Geometric Isomer and Other Related Impurities of Tafluprost Drug Substance and Identification of Major Degradation Compounds by Using LC-MS

Green, Validated HPLC Method Coupled With Fluorescence Detection for the Analysis of Tafluprost in its Pure Form and Ophthalmic Formulation: Application to Aqueous Humor and Content Uniformity Testing

A green, simple and sensitive HPLC method coupled with fluorescence detection was implemented for the quantitative determination of the anti-glaucoma drug tafluprost (TFL). Liquid chromatography was performed on HyperClone™ ODS (C18) column of dimensions; 150 × 4.6 mm i.d. and 5 μm particle size using a green eluent; ethanol:0.01 M phosphate buffer (60:40 v/v, pH 4.5) delivered at 1 mL min-1. Fluorescence detection was accomplished at 220 nm (excitation) and 292 nm (emission). Bimatoprost (BIM) was used as an internal standard (I.S.). In this method, TFL was eluted after 6.70 minutes. The method satisfied International Council for Harmonization (ICH) validation guidelines, as proved by good linearity (r = 0.9999, over the range 0.05-2 μg mL-1), accuracy (recovery average 100.13 ± 1.27%), precision, robustness and specificity. The limit of detection and limit of quantification were found to be 0.016 and 0.048 μg mL-1, respectively. The proposed method has been successfully applied for the estimation of TFL in eye drops and aqueous humor. For the first time, the approach was applied with acceptable results for the evaluation of the uniformity of TFL eye drops content. Furthermore, Green Analytical Procedure Index (GAPI) and analytical Eco-scale were used to prove that the proposed HPLC method is environmentally friendly.

Green HPLC method with time programming for the determination of the co-formulated eye drops of tafluprost and timolol in their challengeable ratio

A new, simple and selective HPLC method was implemented for the simultaneous estimation of tafluprost (TFL) and timolol (TIM) in their new anti-glaucoma combination in the challengeable ratio of 3 and 1000 for TFL and TIM, respectively. Separation was achieved using a BDS Hypersil phenyl column and a mobile phase made up of acetonitrile: 0.015 M phosphate buffer (50:50 v/v, pH 3.5) delivered at 1 mL min⁻¹ and the separation was completed in less than 6 min. UV detection was time programmed at 220 nm for the first 4.5 min and later at 254 nm. Mebeverine (MEB) was used as an internal standard (I.S.). The linearity was observed in the ranges of 0.6–45 and 50–2000 µg mL⁻¹ with limits of detection (LOD) of 0.18, 16.48 µg mL⁻¹ and limits of quantification (LOQ) of 0.55, 49.94 µg mL⁻¹ for TFL and TIM, respectively. The method satisfied International Council for Harmonization (ICH) validation guidelines. The study was extended to the estimation of the studied drugs in their co-formulated eye drops as well as in their single dosage forms with acceptable percentage recoveries. Moreover, Green Analytical Procedure Index (GAPI) and analytical Eco-scale were investigated to confirm the greenness of the proposed HPLC method.

Isolation, characterization, and docking studies of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro-4-phenoxybuta-1, 3-dienyl)-3,5- dihydroxycyclopentyl) hept-5-enoate, an Impurity of Tafluprost

INTRODUCTION

The origin, isolation, and characterization of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro4-phenoxybuta-1, 3-dienyl)-3, 5-dihydroxycyclopentyl) hept-5-enoate, an impurity found in the preparation of an antiglaucoma agent-Tafluprost has been described.

MATERIALS AND METHODS

Further, an enantiospecific synthesis of (Z)-isopropyl 7-((1R, 2R, 3R, 5S)-2-((1E, 3Z)-3-fluoro-4- phenoxybuta-1, 3-dienyl)-3, 5-dihydroxycyclopentyl) hept-5-enoate has been revealed using deoxofluorination as a key transformation of the strategy.

RESULTS AND DISCUSSIONS

Moreover, the impurity showing anti-glaucoma properties in docking studies with respect to bimatoprost.

CONCLUSION

The extent of our work towards docking studies, the present impurity molecule showing almost the same biological activity with respect to Tafluprost.

Green highly sensitive spectrofluorimetric method for rapid determination of tafluprost in its pure form and ophthalmic formulation

A green, simple and easy spectrofluorimetric method was studied for rapid estimation of tafluprost (TFL). The native fluorescence of TFL was measured at 292 nm after excitation at 220 nm. The results were linear in water over the concentration range 50-600 ng ml^-1 with a correlation coefficient r = 0.9999 and intercept 1.1555. The limit of detection and limit of quantification were found to be 7.87 and 23.86 ng ml^-1 , respectively. Neither different pH nor surfactants enhanced the fluorescence intensity. The high sensitivity of this spectrofluorimetric method makes it suitable for analysis of low concentrations of tafluprost in commercially available ophthalmic formulations. This procedure was validated according to International Council for Harmonisation Guidelines.