Simultaneous estimation of troxerutin and calcium dobesilate in presence of the carcinogenic hydroquinone using green spectrofluorimetric method

In the present study, we conducted two facile and highly sensitive spectrofluorimetric approaches in order to quantify the vasoprotective agents; troxerutin (TROX) and calcium dobesilate (DOB) in the presence of hydroquinone (HQ) (as a highly toxic impurity and potential degradation product of DOB) in commercial formulations and human plasma. The first approach relies simply on using ethanol as an eco-friendly solvent for the estimation of DOB at 345 nm after being excited at 305 nm. The linearity was carefully investigated between DOB concentration and the relative fluorescence intensity in the range of 0.05-0.8 µg ml-1. Due to the high method simplicity and sensitivity, applying the first approach to quality control analysis and spiked human plasma samples with mean % recoveries 100.74 ± 3.71 adds another merit. The second approach involved rapid conventional fluorimetric estimation of ethanolic TROX solution in TROX/DOB combined dosage forms at 455/350 nm (emission/excitation) with a linear calibration chart covering the range of 0.1-1.2 µg ml-1. Moreover, the second approach involved a comprehensive study in a trial to solve the problem of superposition of DOB and HQ graph adopting the first derivative synchronous fluorimetric mechanism in ethanol at Δλ = 60 nm. Therefore, DOB was measured at 286 and 323 nm, while HQ could be quantitated at 301 nm. The Beer-Lambert Law has complied over the ranges of 0.1-1.0 and 0.02-0.4 µg ml-1 for DOB and HQ, respectively. Guidelines adopted by the International Council of Harmonization (ICH) were used to validate the target approaches. The developed methods are more convenient for routine quality control laboratory instead of the time-consuming and sophisticated reported techniques. Moreover, different aspects of evaluating the greenness of the proposed approaches were conducted to have a complete image of their environmental impact.

Validated Chromatographic Methods for the Simultaneous Estimation of Etamsylate and Mefenamic Acid in the Presence of Their Main Impurities

Background:

Etamsylate (ETS), a haemostatic drug, is formulated with mefenamic acid (MFA) for pain relief.

Objective:

The aim of this work was to develop chromatographic methods for the estimation of ETS and MFA in the presence of their main impurities. These methods could be used in the routine analysis in quality control laboratories.

Methods:

The first method was RP-HPLC method, the separation was carried out on an Inertsil® ODS- 3V C18 column using a mobile phase composed of acetonitrile: potassium dihydrogen phosphate buffer adjusted to pH 7 with 0.1 N NaOH (55: 45, v/v) at a flow rate of 1 ml/ min. The detection was carried out at 220 nm. The second method was a TLC-densitometric method where the studied components were separated using a developing system composed of dichloromethane: ethyl acetate: methanol: triethylamine (6: 2: 2: 0.5, v/v/v/v) on TLC silica gel 60 F254 plates, followed by densitometric scanning at 300 nm.

Results:

In RP-HPLC method, the peaks were sharp and well separated, good retention times were obtained. Linearity was obtained over the concentration range 20-90 µg/ml, for both ETS and MFA. In the TLC-densitometric method, well separation of drug spots and linear relationship were achieved over the concentration range of 0.4-2.8 µg/spot, for both ETS and MFA. Method validation was conducted according to ICH guidelines.

Conclusion:

The developed methods were applied for the determination of the cited drugs in laboratory prepared mixtures and in tablets containing the two drugs. The methods are simple and precise and can be used for routine analysis of the drugs in combined dosage forms in quality control laboratories.

Micellar HPLC Method for Simultaneous Determination of Ethamsylate and Mefenamic Acid in Presence of Their Main Impurities and Degradation Products

An eco-friendly sensitive, rapid and less hazardous micellar liquid chromatographic method was developed and validated for the simultaneous analysis of ethamsylate (ETM) and mefenamic acid (MFA) in the presence of hydroquinone (HQ) and 2,3-dimethylaniline (DMA) the main impurities of ETM and MFA, respectively. Good chromatographic separation was attained using Eclipse XDB-C8 column (150 mm × 4.6 mm, 5 μm particle size) adopting UV detection at 300 nm with micellar mobile phase consisting of 0.12 M sodium dodecyl sulfate, 0.3% triethylamine and 15% 2-propanol in 0.02 M orthophosphoric acid (pH 7.0) at 1.0 mL/min. The analytes were well resolved in <6.0 min, ETM (t_R = 1.55 min), HQ (t_R = 1.95 min), MFA (t_R = 4.55 min) and DMA (t_R = 5.80 min). Different validation parameters were examined as recommended by international conference on harmonization (ICH) guidelines. The method was linear over the concentration ranges of 0.5-18.0, 0.5-20.0, 0.01-0.5 and 0.02-0.2 µg/mL with limits of detection of 0.118, 0.159, 0.005 and 0.005 µg/mL and limits of quantification of 0.358, 0.482, 0.014 and 0.015 µg/mL for ETM, MFA, HQ and DMA, respectively. The suggested method was successfully applied for the determination of the two drugs in their bulk powder, laboratory-prepared mixtures, single-ingredient and co-formulated tablets. The obtained results were in accordance with those of the comparison method. The method can also detect trace amounts of HQ and DMA as the main impurities of ETM and MFA, respectively, within the BP limit (0.1%) for both impurities. Furthermore, it is a stability-indicating one for the determination of ETM in its pure form, single-component tablet and co-formulated tablets with other drugs.

Two liquid chromatographic approaches for the simultaneous determination of xipamide and its degradation product (2,6-xylidine) using time-programmed fluorescence detection

A study of the performance of reversed-phase chromatography with a programmable multiwavelength fluorimetric technique using either conventional hydro-organic or micellar eluent is established for the determination of xipamide (XIP) in the presence of its degradation product, 2,6-xylidine (XY). In conventional liquid chromatography (CLC), the analyses were carried out on a Promosil ODS 100 Å column (250 mm × 4.6 mm i.d., 5 μm) using a mobile phase consisting of methanol/0.1 M phosphate buffer (65: 35, v/v) at pH 4.0. For micellar liquid chromatography (MLC), a short Spherisorb column (150 mm × 4.6 mm i.d., 5 μm) was employed in conjunction with a greener mobile phase (pH 5.0) containing 0.1 M sodium dodecyl sulfate and 15% n-propanol. CLC proved to be superior to MLC in terms of sensitivity for the determination of the degradation product because it could detect trace amounts down to 10.0 ng/ml of XY as a degradation product in XIP. However, MLC represents an eco-friendly approach for the simultaneous determination of XIP and XY. In addition, the opportunity for the direct introduction of biological matrices into the chromatographic system is one of the distinctive benefits of MLC. The proposed methods were applied for the determination of XIP in its tablets, human urine and content uniformity testing. The results of the proposed methods were statistically compared with those obtained using the comparison fluorimetric method, revealing no significant differences in the performance of the methods regarding accuracy and precision.