Simultaneous determination of phenazopyridine HCl and trimethoprim in presence of phenazopyridine HCl impurity by univariate and multivariate spectrophotometric methods - Quantification of phenazopyridine HCl impurity by univariate methods.

Three univariate and two multivariate spectrophotometric methods were developed and subsequently validated to determine phenazopyridine HCl (PHZ) and trimethoprim (TMP) in the presence of 2,6-Diaminopyridine (2,6-DAP). The first univariate method depends on direct determination of phenazopyridine by measuring its absorbance at 412 nm and performed in concentration range of 1.00-10.00 µg/mL. Then the contribution of phenazopyridine is removed by dividing the mixture spectrum with PHZ divisor (5 µg/mL) after that the constant is mathematically subtracted and finally the generated spectrum is multiplied with the PHZ divisor. These steps eliminate PHZ contribution and the recovered spectrum is that of TMP and 2,6-DAP only where different methods can be applied to determine TMP and 2,6-DAP through this binary mixture spectrum. The first method to determine both components depends on measuring both TMP and 2,6-DAP through their first derivative (1DD) spectra at 244.70 and 259.60 nm for TMP and 2,6-DAP, respectively with concentration ranges of 4.00-24.00 µg/mL TMP and 4.00-26.00 µg/mL 2,6-DAP. The second method depends on application of the isoabsorptive method which was used for TMP determination at its isoabsorptive point with 2,6-DAP at 242.64 nm with concentration range 1.00-20.00 µg/mL for TMP. The developed univariate methods were successfully applied to determine PHZ, TMP and PHZ impurity (2,6-DAP). Two multivariate methods were applied for determination of PHZ and TMP in presence of 2,6-DAP namely, Principle Component Regression (PCR) and Partial Least Squares (PLS). The results of the two models show that simultaneous determination of PHZ and TMP in presence of PHZ impurity can be performed in the concentration ranges of 6.00-14.00 µg/mL PHZ and 24.00-56.00 µg/mL TMP. All the proposed methods were successfully applied to analyze PHZ and TMP in pharmaceutical formulations without interference from the dosage form additives and the results were statistically compared with the reported method.

Effect of Genetic Algorithm-Based Wavelength Selection as a Preprocessing Tool on Multivariate Simultaneous Determination of Paracetamol, Orphenadrine Citrate, and Caffeine in the Presence of p-Aminophenol Impurity.

BACKGROUND: The utilization of selection methods such as genetic algorithm (GA) aims to construct better partial least squares (PLS) and principal component regression (PCR) models than those established from the full-spectrum range. OBJECTIVE: Determination of paracetamol (PAR), orphenadrine citrate (Or.cit), and caffeine (CAF) in the presence of PAR nephrotoxic impurity [p-aminophenol (PAP)]. GA was applied to select the optimum wavelengths used. METHODS: A calibration set was prepared in which the three drugs, together with PAP, were modeled by multilevel multifactor design. This calibration set was used to build the PLS and PCR models, either with or without preprocessing the data using GA. RESULTS: Results were compared with and without preprocessing, and this revealed that GA can find an optimized combination of spectral wavelengths, yielding a lower root mean square error of prediction as well as a lower number of latent variables used. The results of the two models show that simultaneous determination of the aforementioned drugs can be performed in the concentration ranges of 20-60, 3-11, and 1-9 µg/mL for PAR, Or.cit, and CAF, respectively. CONCLUSIONS: The proposed models were applied for the determination of the three drugs in their pharmaceutical formulations, and the results were verified by the standard addition technique. HIGHLIGHTS: GA can be useful as a wavelength selection tool before applying multivariate PLS and PCR methods. GA gives an improvement in the predictive ability of the models with lower RMSEP and less number of latent variables (LVs). The proposed PLS, PCR, GA-PLS, and GA-PCR spectrophotometric methods were able to determine paracetamol, orphenadrine citrate, and caffeine in the presence of p-aminophenol and severe spectral overlapping.

Development and Validation of Chromatographic Methods for Simultaneous Determination of Paracetamol, Orphenadrine Citrate and Caffeine in Presence of P-aminophenol; Quantification of P-aminophenol Nephrotoxic Impurity Using LC-MS/MS.

Three chromatographic methods were developed, optimized and validated for Paracetamol (PAR), Orphenadrine citrate (Or.cit) and Caffeine (CAF) determination in their mixture and in presence of PAR toxic impurity; P-aminophenol (PAP) in tablets. The first method is based on a thin layer chromatography combined with densitometry. Separation was achieved using silica gel 60 F254 TLC plates and dichloromethane:methanol:acetone:glacial acetic acid (9:1:0.5:0.3, v/v/v) as a developing system at 230 nm. The second method is based on high-performance liquid chromatography with diode array detection. The proposed compounds are separated on a reversed phase C18 analytical column using phosphate buffer (pH 9; 0.05 M) and methanol (80:20, v/v) at 1.2 mL/min. Linear regressions are obtained in the range of 1-500 µg/mL, 25-1000 µg/mL and 1-400 µg/mL for PAR, Or.cit and CAF, respectively. Quantification of the toxic PAP is carried out using LC-MS-MS by electrospray ionization in the positive mode using triple quadrupole mass spectrometry. The limit of quantification for PAP is 1 ng/mL. All methods are validated according to the ICH guidelines and successfully applied to determine PAR, Or.cit, CAF and PAP in pure powder and in combined tablets dosage form without interference from excipients.

Simultaneous Quantification of Chlorpheniramine, Phenylephrine, Guaifenesin in Presence of Preservatives with Detection of Related Substance Guaiacol in their Cough Syrup by RP-HPLC and TLC-Densitometric Methods.

Two sensitive chromatographic methods have been developed, and validated for chlorpheniramine maleate (CM), phenylephrine (PE) and guaifenesin (GF) determination in their mixture and in presence of GF related substance guaiacol (GL) and preservative namely; sodium benzoate (NaB). The first method was based on thin layer chromatographic separation (TLC) followed by densitometric determination of the separated spots. The separation was achieved using silica gel 60 F254 TLC plates and ethyl acetate: methanol: toluene: ammonia (7:1.5:1:0.5, by volume) as a developing system. Densitometric quantification of the three drugs was carried by the reflectance mode at 270 nm. The second method was based on the use of high-performance liquid chromatography with diode array detection, by which the proposed components were separated on a reversed phase C18 analytical column using phosphate buffer pH 2.9 (containing 0.1 g Heptane-1-sulphonic acid sodium salt) and acetonitrile (85:15, v/v) at 0.8 mL/min for 4 minutes then 1 mL/min till end of the run using flow rate online switching technique. Both methods were validated according to the ICH guidelines and successfully applied for the determination of CM, PE, and GF in pure powder and in combined cough syrup without interference from the excipients.

Analytical Eco-Scale for Assessing the Greenness of a Developed Potentiometric Method for Lomefloxacin Hydrochloride Determination in its Different Dosage Forms, Plasma, and Dissolution Medium.

Background: Traditional methods for Lomefloxacin hydrochloride (LOM) determination involve pretreatment steps, which extend analysis time and use hazardous chemicals. Objective: The ability to provide a rapid route without sample pretreatment for quantitative determination of compounds via a low-cost instrument is a challenging task. In this work, a simple potentiometric method was developed to determine the antibacterial LOM via in-house fabricated ion selective electrodes. Methods: Different sensors were fabricated using a poly vinyl chloride-based membrane, potassium tetrakis(4-chlorophenyl) borate as a cation exchanger, and 2-Nitrophenyl octyl ether as a plasticizer (sensor 1). To increase the selectivity of sensor 1, a selective molecular recognition component 2-hydroxypropyl-ß-cyclodextrin was used as ionophore (sensor 2). Results: The proposed method was validated according to International Union of Pure and Applied Chemistry recommendations, in which the proposed sensors show a linear dynamic range from 1 × 10-5 to 1 × 10-2 mol/L, with Nernstian slopes of 55.829 and 58.229 mV/decade for sensors 1 and 2, respectively. It was applied to determine LOM in bulk powder, in different dosage forms, and in plasma with no sample pretreatment. Also, the suggested method can be used as a green, in-line bench top real-time analyzer for in-process monitoring of LOM release from its tablets, under U.S. Food and Drug Administration dissolution regulations, with clear discrimination from common excipients. Results obtained by the proposed potentiometric method were compared with those obtained by a reported HPLC method. Conclusions: The proposed method is considered as a perfect alternative to traditional reported methods for LOM determination.

Multivariate Validated Models for Simultaneous Determination of Ibuprofen and Famotidine in the Presence of Related Substances.

Two multivariate validated spectrophotometric methods, namely partial least-squares (PLS) and principal component regression (PCR), were developed and validated for the determination of ibuprofen and famotidine in presence of famotidine degradation products and ibuprofen impurity (4-isobutylacetophenone). A calibration set was prepared in which the two drugs together with the degradation products and impurity were modeled using a multilevel multifactor design. This calibration set was used to build the PLS and PCR models. The proposed models successfully predicted the concentrations of both drugs in validation samples, with low root mean square error of cross validation (RMSECV) percentage. The method was validated by the estimate of the figures of merit depending on the net analyte signal. The results of the two models showed that the simultaneous determination of both drugs could be performed in the concentration ranges of 100-500 µg/mL for ibuprofen and 5-25 µg/mL for famotidine. The proposed multivariate calibration methods were applied for the determination of ibuprofen and famotidine in their pharmaceutical formulation, and the results were verified by the standard addition technique.

Development and validation of chromatographic methods for simultaneous determination of ibuprofen and famotidine in presence of related substances in pharmaceutical formulations.

Two validated methods for the simultaneous determination of ibuprofen and famotidine in the presence of ibuprofen impurity (4-isobutylacetophenone) and or famotidine degradation products were described. The first method was a simple TLC method where separation was performed on silica gel platesusing ethyl acetate: methanol: ammonia (9:2:1, by volume) as a mobile phase. Rf values were found to be 0.40, 0.94, 0.66, 0.27, 0.83 for ibuprofen, 4-isobutylacetophenone, famotidine, famotidine acid and basic degradation products, respectively. The second method is by HPLC on C18 column using methanol: phosphate buffer pH 3 (80:20, v/v) as a mobile phase. Retention times were found to be 2.2, 9.9, and 8.6 for famotidine, ibuprofen, and 4-isobutylacetophenone, respectively. Both methods were validated according to the ICH guidelines and applied for the determination of the two drugs in pure powder and combined dosage form without interference from the excipients.

Application of the ratio difference spectrophotometry to the determination of ibuprofen and famotidine in their combined dosage form: comparison with previously published spectrophotometric methods.

Ratio difference spectrophotometric method was developed for the determination of ibuprofen and famotidine in their mixture form. Ibuprofen and famotidine were determined in the presence of each other by the ratio difference spectrophotometric (RD) method where linearity was obtained from 50 to 600µg/mL and 2.5 to 25µg/mL for ibuprofen and famotidine, respectively. The suggested method was validated according to ICH guidelines and successfully applied for the analysis of ibuprofen and famotidine in their pharmaceutical dosage forms without interference from any additives or excipients.