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.

Factorial design-assisted reverse phase HPLC-UV approach for the concurrent estimation of cetirizine and azelastine in aqueous humor.

A new analytical quality by design-assisted HPLC-UV approach is presented, for the first time, for the concurrent determination of cetirizine (CTZ) and azelastine (AZE) in raw materials, commercial eye drops and aqueous humor. The two drugs are co-administered as eye drops in severe ocular allergies. A 23 full factorial design was adopted for the chromatographic optimization to ensure the best analytical performance and reliability, as well as to save time, effort and solvent consumption. The parameters, including pH, acetonitrile ratio, and flow rate, were selected as independent factors. The responses analyzed were resolution and tailing of peaks. The separation was achieved through isocratic elution on C8 column with mobile phase made up of acetonitrile: 0.3% triethylamine of pH 5 (60:40 v/v) at a flow rate of 1.2 mL min-1 and detection at 216 nm. The elution time was less than 6 min. The approach was fully validated in accordance with International Council for Harmonization (ICH) guidelines. Good linearity was achieved over the concentration ranges of 1.0-30 and 0.5-10 µg mL-1 with limits of detection of 0.310 and 0.158 µg mL-1 and limits of quantification of 0.940 and 0.479 µg mL-1 for CTZ and AZE, respectively, with correlation coefficients of 0.9998. The intra- and inter-day precisions were lower than 2%. The good sensitivity of the approach permits the analysis of CTZ and AZE in spiked aqueous humor with mean percentage recoveries of 100.93 ± 1.42 and 100.11 ± 1.55, respectively. The statistical comparison between results of the developed method and the comparison method revealed no differences, indicating the accuracy of the method.

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.

Simultaneous determination of cetirizine, phenyl propanolamine and nimesulide using third derivative spectrophotometry and high performance liquid chromatography in pharmaceutical preparations.

BACKGROUND: The combination between cetirizine (CET), phenylpropanolamine (PPA) and nimesulide (NMS) under trade name Nemeriv Cp tablet is prescribed for nasal congestion, cold, sneezing, and allergy. Among all published methods for the three drugs; there is no reported method concerning estimation of CTZ, PPA and NMS simultaneously and this motivates us to develop new and simple methods for their assay in pure form and tablet preparations. RESULTS: Two new methodologies were described for the simultaneous quantification of cetirizine (CTZ), PPA and NMS. Spectrophotometric procedures relies on measuring the amplitudes of the third derivative curves at 238 nm for CTZ, 218 nm for PPA and 305 nm for NMS. The calibration graphs were rectilinear over the ranges of 8-90 µg/mL for CTZ, 20-100 µg/mL for PPA and 20-200 µg/mL for NMS respectively. Regarding the HPLC method; monolithic column (100 mm × 4.6 mm i.d) was used for the separation. The used mobile phase composed of 0.1 M phosphate buffer and methanol in the ratio of 40:60, v/v at pH 7.0. The analysis was performed using UV detector at 215 nm. Calibration curves showed the linearity over concentration ranges of 5-40, 10-100 and 10-120 µg/mL for CTZ, PPA and NMS. CONCLUSION: Application of the proposed methods to the laboratory prepared tablets was carried out successfully. The results were compared with those obtained from previously published methods and they were satisfactory. Graphical abstract Graphical abstract represents the chemical structures, representative chromatogram for the HPLC separation of a PPA, b NMS and c CTZ and third derivative absorption spectra of a PPA, b NMS and c CTZ for the spectrophotometric method.

Spectrofluorimetric analysis of gemifloxacin mesylate in pharmaceutical formulations.

A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of gemifloxacin mesylate (GFX) in tablets. The method is based on measuring the native fluorescence of GFX in isopropanol at 400 nm after excitation at 272 nm. The fluorescence-concentration plot was rectilinear over the range of 0.01-0.50 µg/mL with a lower detection limit of 1.19 ng/mL and quantification limit of 3.6 ng/mL. The method was fully validated and successfully applied to the determination of GFX tablets with an average percentage recovery of 99.65 ± 0.532. The method was extended to the stability study of GFX. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to International Conference on Harmonization guidelines. The rate of GFX degradation was found at its highest in acidic conditions, and in its lowest in the neutral one. However, it was stable under dry heat and photolytic degradation conditions.