Development of Ecofriendly Derivative Spectrophotometric Methods for the Simultaneous Quantitative Analysis of Remogliflozin and Vildagliptin from Formulation

Stability-Indicating HPTLC Method for Determination of Remogliflozin Etabonate and Vildagliptin in Tablets

A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic (HPTLC) method is developed for the simultaneous estimation of remogliflozin etabonate and vildagliptin in the presence of their degradation products. The separation was performed in thin layer chromatography plate precoated with silica gel G60F254. The mobile phase consists of methanol:ethyl acetate:toluene:ammonia (1.5:4:4.5:0.1, v/v/v/v). Detection and quantification are performed with densitometer at 212 nm. The Rf values of remogliflozin etabonate and vildagliptin are 0.53 and 0.42, respectively. Degradation studies for the two drugs were carried out in acidic, alkaline, neutral, oxidative, photolytic and thermal stress conditions and analyzed. The suitability of this method for the quantitative determination of the compounds is proved by validation in accordance with the requirements laid down by International Conference on Harmonization (ICH). Linearity was found over the concentration range of 200-1000 ng/band with correlation coefficient of 0.9936 for remogliflozin etabonate and 100-500 ng/band with correlation coefficient of 0.9912 for vildagliptin. The method was successively applied to tablets containing two drugs and found to have no chromatographic interferences from the tablet excipients. The degradant formed was not interfering with estimation of two drugs makes the method more selective for the purpose intended.

Chemometric-Based AQbD and Green Chemistry Approaches to Chromatographic Analysis of Remogliflozin Etabonate and Vildagliptin

BACKGROUND

According to the green chemistry approach, during method development, the usage of toxic and carcinogenic organic solvents should be avoided or minimized for the safety of the environment and analysts. The chromatographic methods such as reverse-phase high-pressure liquid chromatography (RP-HPLC) and high-performance thin-layer chromatography (HPTLC) include the usage of class 2 organic solvents as per the International Council for Harmonization (ICH) Q3C (R6) guideline. The chromatographic analysis by HPTLC requires less organic solvent compared to the RP-HPLC method.

OBJECTIVE

Hence, HPTLC-based chromatographic analysis of vildagliptin (VIL) and remogliflozin etabonate (RMG) has been carried out using green chemistry and analytical quality by design (AQbD) approaches.

METHOD

The principal component analysis (PCA)-based chemometric analysis was applied for the identification of critical method variables (CMV) for the development of the method. The design of experiments (DoE)-based Box-Behnken design (BBD) was applied for response surface modeling (RSM) and optimization of CMV. The analytical design space (ADS) and analytical control point were navigated for the development of the HPTLC method as per the quality target analytical profile.

RESULTS

The chromatographic analysis of VIL and RMG was carried out using silica gel G60 F254 as the stationary phase and acetone-ethyl acetate-water-triethylamine (7.0 + 2.5 + 0.3 + 0.2, v/v) as the mobile phase. The HPTLC method was validated as per the ICH Q2 (R1) guideline. The HPTLC method was applied for the assay of fixed-dose combinations (FDCs) of VIL and RMG, and the results were found to comply with their labeled claim.

CONCLUSIONS

The developed method included the usage of organic solvents that belong to the class 3 category as per the ICH Q3C (R6) guideline. Hence, the developed method can be used as an eco-friendly alternative to published chromatographic methods for quality control and routine analysis of FDCs of VIL and RMG in the pharmaceutical industry.

HIGHLIGHTS

Chromatographic analysis of VIL and RMG using green chemistry and AQbD approaches. Application of the method for assay of drugs in their combined pharmaceutical dosage forms.

Innovative spectrofluorimetric determination of vildagliptin based on a "switch off/on" NS-doped carbon dot nanosensor

A simple, fast, and green one-step microwave pyrolysis approach was proposed for the synthesis of highly fluorescent nitrogen/sulfur-doped carbon dots (NS-CDs). The proposed NS-CDs were prepared in only one minute from citric acid and thiosemicarbazide. In the presence of Cu2+, the fluorescence of NS-CDs was significantly quenched ("turn off") through the formation of a non-fluorescent NS-CDs/Cu2+ complex. This designed sensor could be applied for label-free determination of vildagliptin based on the competition between vildagliptin and the functional groups on NS-CDs for Cu2+ complexation, and hence NS-CD fluorescence recovery ("turn on"). Under the optimized conditions, the developed probe (NS-CDs/Cu2+) demonstrated a good sensing performance for vildagliptin with linearity in the range of 45-240 μM and a detection limit of 13.411 μM. Owing to its sensitivity, this sensor was successfully applied for vildagliptin determination in human urine samples.

Sensitivity Enhanced Ecofriendly UV Spectrophotometric Methods for Quality Control of Telmisartan and Benidipine Formulations: Comparison of Whiteness and Greenness with HPLC Methods

The development of an environmentally friendly analytical technique for simultaneous measurement of medicines with large concentration differences is difficult yet critical for environmental protection. Hence, in this work, new manipulated UV-spectroscopic methods with high scaling factors were established for concurrent quantification of telmisartan (TEL) and benidipine (BEN) in fixed-dose combinations. Two different methods were developed and established by calculation of peak height at zero crossing point of second derivative and the ratio of first derivative spectra with a scaling factor of 200 and 100, respectively. The absorption difference between the peaks and troughs of the ratio spectra, as well as continuous subtraction from ratio spectra, were established as additional methods. In addition, new procedures were validated using ICH recommendations. The proposed methods’ linearity curves were constructed in the range of 0.5–10 µg mL⁻¹ and 1–30 µg mL⁻¹ for BEN and TEL, respectively, under optimized conditions. Furthermore, both the detection (0.088–0.139 µg mL⁻¹ for BEN and 0.256–0.288 µg mL⁻¹ for TEL) and quantification limits (0.293–0.465 µg mL⁻¹ for BEN and 0.801–0.962 µg mL⁻¹ for TEL) were adequate for quantifying both analytes in the formulation ratios. The accuracy and precision were confirmed by the good recovery percent (98.37%–100.6%), with low percent relative error (0.67%–1.70%) and less than 2 percent relative standard deviation, respectively. The specificity of the methods was proven by accurate and precise outcomes from the standard addition method and analysis of laboratory mixed solutions with large differences in concentrations of both analytes. Finally, the BEN and TEL content of the formulations was determined simultaneously without prior separation using these first ever reported spectroscopic methods. Furthermore, developed UV derivative spectroscopic methods demonstrated high greenness and whiteness when compared to the reported HPLC methods. These findings show that the projected methods were effective, practical, and environmentally acceptable for quality control of BEN and TEL in multicomponent formulations.

An Experimental Design Approach to Quantitative Expression for Quality Control of a Multicomponent Antidiabetic Formulation by the HILIC Method

A rapid and reproducible hydrophilic liquid chromatography (HILIC) process was established for concomitant determination of remogliflozin etabonate (RE), vildagliptin (VD), and metformin (MF) in a formulation. A face-centered central composite experimental design was employed to optimize and predict the chromatographic condition by statistically studying the surface response model and design space with desirability close to one. A HILIC column with a simple mobile phase of acetonitrile (65% v/v) and 20 mM phosphate buffer (35% v/v, pH 6, controlled with orthophosphoric acid) was used to separate RE, VD, and MF. RE, VD, and MF were separated in 3.6 min using an isocratic mode mobile phase flow at a flow rate of 1.4 mL at room temperature, and the analytes were examined by recording the absorption at 210 nm. The developed HILIC method was thoroughly validated for all parameters recommended by ICH, and linearity was observed in the ranges 20−150 µg/mL, 10−75 µg/mL, and 50−750 µg/mL for RE, VD, and MF, respectively, along with excellent regression coefficients (r2 > 0.999). The calculated percentage relative deviation and relative error ascertained the precision and accuracy of the method. The selectivity and accuracy were further confirmed by the high percentage recovery of added standard drugs to the formulation using the standard addition technique. The robustness of the HILIC processes was confirmed by developing a half-normal probability plot and Pareto chart, as the slight variation of a single factor had no significant influence on the assay outcomes. Utilization of the optimized HILIC procedure for concurrent quantification of RE, VD, and MF in solid dosage forms showed accurate and reproducible results. Hence, the fast HILIC method can be regularly employed for the quality assurance of pharmaceutical preparations comprising RE, VD, and MF.