Dalia Mohamed

A comparative study of smart spectrophotometric methods for simultaneous determination of a skeletal muscle relaxant and an analgesic in combined dosage form.

Six simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the analgesic drug; paracetamol (PARA) and the skeletal muscle relaxant; dantrolene sodium (DANT). Three methods are manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and mean centering (MC). The other three methods are utilizing the isoabsorptive point either at zero order namely; absorbance ratio (AR) and absorbance subtraction (AS) or at ratio spectrum namely; amplitude modulation (AM). The proposed spectrophotometric procedures do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined dosage form. Standard deviation values are less than 1.5 in the assay of raw materials and capsules. The obtained results were statistically compared with each other and with those of reported spectrophotometric ones. The comparison showed that there is no significant difference between the proposed methods and the reported methods regarding both accuracy and precision.

A comparative study of smart spectrophotometric methods for simultaneous determination of sitagliptin phosphate and metformin hydrochloride in their binary mixture.

Simple, specific, accurate and precise spectrophotometric methods were developed and validated for the simultaneous determination of the oral antidiabetic drugs; sitagliptin phosphate (STG) and metformin hydrochloride (MET) in combined pharmaceutical formulations. Three methods were manipulating ratio spectra namely; ratio difference (RD), ratio subtraction (RS) and a novel approach of induced amplitude modulation (IAM) methods. The first two methods were used for determination of STG, while MET was directly determined by measuring its absorbance at λmax 232 nm. However, (IAM) was used for the simultaneous determination of both drugs. Moreover, another three methods were developed based on derivative spectroscopy followed by mathematical manipulation steps namely; amplitude factor (P-factor), amplitude subtraction (AS) and modified amplitude subtraction (MAS). In addition, in this work the novel sample enrichment technique named spectrum addition was adopted. The proposed spectrophotometric methods did not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined. The selectivity of the developed methods was investigated by analyzing laboratory prepared mixtures of the drugs and their combined pharmaceutical formulations. Standard deviation values were less than 1.5 in the assay of raw materials and tablets. The obtained results were statistically compared to that of a reported spectrophotometric method. The statistical comparison showed that there was no significant difference between the proposed methods and the reported one regarding both accuracy and precision.

Novel contribution to the simultaneous analysis of certain hypoglycemic drugs in the presence of their impurities and degradation products utilizing UPLC-MS/MS

A novel ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) method was established for simultaneous determination of three hypoglycemic drugs namely; sitagliptin (STG), vildagliptin (VLG) and metformin (MET) in the presence of their degradation products and STG related impurities. Chromatographic separation was accomplished on a Hypersil gold 50 mm × 2.1 mm (1.9 μm) column, using acetonitrile and 0.2% formic acid aqueous solution as the mobile phase with a gradient elution. Electrospray ionization (ESI) source was operated in the positive ion mode. The selected reaction monitoring (SRM) mode on a triple quadrupole mass spectrometer was used to quantify the drugs utilizing the transitions of 408.12 → 235.24 (m/z), 304.33 → 154.32 (m/z), 130.12 → 71.32 (m/z) and 255.75 → 166.15 (m/z), for STG, VLG, MET and diphenhydramine (IS), respectively. The method has displayed a lower limit of detection of 1.50 ng mL−1, 1.50 ng mL−1 and 3.00 ng mL−1 for STG, VLG and MET, respectively. The drugs were subjected to forced degradation where it was concluded that STG, VLG and MET were highly susceptible for alkaline stress conditions. In addition, the study of the degradation kinetics of the drugs has proved that the degradation follows a pseudo-first-order reaction. The proposed method was effectively applied for the analysis of laboratory prepared mixtures as well as combined pharmaceutical formulations. No significant difference was found regarding accuracy and precision upon statistical comparison of the obtained results with those of the reported method. Validation was conducted in compliance with the ICH guidelines proving the method to be selective, linear, precise and accurate. The simplicity and sensitivity of this method allows its use in the quality control of the cited drugs.

Different mathematical processing of absorption, ratio and derivative spectra for quantification of mixtures containing minor component: An application to the analysis of the recently co-formulated antidiabetic drugs; canagliflozin and metformin

In the presented work several spectrophotometric methods were performed for the quantification of canagliflozin (CGZ) and metformin hydrochloride (MTF) simultaneously in their binary mixture. Two of these methods; response correlation (RC) and advanced balance point-spectrum subtraction (ABP-SS) were developed and introduced for the first time in this work, where the latter method (ABP-SS) was performed on both the zero order and the first derivative spectra of the drugs. Besides, two recently established methods; advanced amplitude modulation (AAM) and advanced absorbance subtraction (AAS) were also accomplished. All the proposed methods were validated in accordance to the ICH guidelines, where all methods were proved to be accurate and precise. Additionally, the linearity range, limit of detection and limit of quantification were determined and the selectivity was examined through the analysis of laboratory prepared mixtures and the combined dosage form of the drugs. The proposed methods were capable of determining the two drugs in the ratio present in the pharmaceutical formulation CGZ:MTF (1:17) without the requirement of any preliminary separation, further dilution or standard spiking. The results obtained by the proposed methods were in compliance with the reported chromatographic method when compared statistically, proving the absence of any significant difference in accuracy and precision between the proposed and reported methods.

Liquid chromatography-tandem MS/MS method for simultaneous quantification of paracetamol, chlorzoxazone and aceclofenac in human plasma: An application to a clinical pharmacokinetic study

A facile, fast and specific method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous quantitation of paracetamol, chlorzoxazone and aceclofenac in human plasma was developed and validated. Sample preparation was achieved by liquid-liquid extraction. The analysis was performed on a reversed-phase C18 HPLC column (5 μm, 4.6 × 50 mm) using acetonitrile-10 mM ammonium formate pH 3.0 (65:35, v/v) as the mobile phase where atrovastatin was used as an internal standard. A very small injection volume (3 μL) was applied and the run time was 2.0 min. The detection was carried out by electrospray positive and negative ionization mass spectrometry in the multiple-reaction monitoring mode. The developed method was capable of determining the analytes over the concentration ranges of 0.03-30.0, 0.015-15.00 and 0.15-15.00 μg/mL for paracetamol, chlorzoxazone and aceclofenac, respectively. Intraday and interday precisions (as coefficient of variation) were found to be ≤12.3% with an accuracy (as relative error) of ±5.0%. The method was successfully applied to a pharmacokinetic study of the three analytes after being orally administered to six healthy volunteers.

Evaluation of multivariate calibration models with different pre-processing and processing algorithms for a novel resolution and quantitation of spectrally overlapped quaternary mixture in syrup.

A novel approach for the resolution and quantitation of severely overlapped quaternary mixture of carbinoxamine maleate (CAR), pholcodine (PHL), ephedrine hydrochloride (EPH) and sunset yellow (SUN) in syrup was demonstrated utilizing different spectrophotometric assisted multivariate calibration methods. The applied methods have used different processing and pre-processing algorithms. The proposed methods were partial least squares (PLS), concentration residuals augmented classical least squares (CRACLS), and a novel method; continuous wavelet transforms coupled with partial least squares (CWT-PLS). These methods were applied to a training set in the concentration ranges of 40-100 μg/mL, 40-160 μg/mL, 100-500 μg/mL and 8-24 μg/mL for the four components, respectively. The utilized methods have not required any preliminary separation step or chemical pretreatment. The validity of the methods was evaluated by an external validation set. The selectivity of the developed methods was demonstrated by analyzing the drugs in their combined pharmaceutical formulation without any interference from additives. The obtained results were statistically compared with the official and reported methods where no significant difference was observed regarding both accuracy and precision.

Simultaneous quantification of chlorpheniramine, pseudoephedrine, and ibuprofen in antitussive preparation by high-performance liquid chromatography and thin-layer chromatography–densitometric methods

Simple, accurate, precise, sensitive, and validated high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC)—densitometric methods were developed for the simultaneous determination of chlorpheniramine maleate (CPM), pseudoephedrine HCl (PSE), and ibuprofen (IBF) in tablet dosage form. In method A, reversed-phase (RP)-HPLC analysis was performed on Zorbax C8 column (150 mm × 4.6 mm, 5 μm particle size i.d.), using a mobile phase consisting of methanol—acetonitrile—distilled water (pH 4) using orthophosphoric acid in the ratio (80:10:10, v/v) and flow rate of 0.7 mL min−1. Quantification was achieved with ultraviolet (UV) detection at 220 nm. In method B, TLC analysis was carried out on an aluminum-backed sheet of silica gel 60 F254 layer using ethyl acetate—methanol—ammonia (8:2:0.8, v/v) as the mobile phase. Quantification was carried out with UV detection at 262 nm. The validation of the proposed methods was applied according to the International Conference on Harmonization (ICH) guidelines. The suggested methods were successfully applied for the determination of the cited drugs in bulk powder and commercial dosage form.

Novel contribution to the simultaneous monitoring of pramipexole dihydrochloride monohydrate and levodopa as co-administered drugs in human plasma utilizing UPLC–MS/MS

An efficient, selective, sensitive, and rapid ultra-performance liquid chromatography tandem mass spectrometry method was established and validated for the quantification of pramipexole dihydrochloride monohydrate and levodopa simultaneously in human plasma with the aid of diphenhydramine as an internal standard. A simple protein precipitation technique with HPLC grade acetonitrile was efficiently utilized for the cleanup of plasma. The analysis was performed using a Hypersil gold 50 mm × 2.1 mm (1.9 µm) column and a mobile phase of 0.2% formic acid and methanol (90: 10 v/v). The triple-quadrupole mass spectrometer equipped with an electrospray source operated in the positive mode was set up in the selective reaction monitoring mode (SRM) to detect the ion transitions m/z 212.15 →153.01, m/z 198.10→ 135.16, and m/z 255.75 → 166.16 for pramipexole dihydrochloride monohydrate, levodopa, and diphenhydramine, respectively. The method was thoroughly validated according to FDA guidelines and proved to be linear, accurate, and precise over the range 100–4000 pg/mL for pramipexole dihydrochloride monohydrate and 60–4000 ng/mL for levodopa. The proposed method was effectively applied for monitoring both drugs in plasma samples of healthy volunteers.

A Comparative Study of Smart Spectrophotometric Methods and a Densitometric Method for Simultaneous Determination of Binary Mixture of Canagliflozin and Metformin Hydrochloride

Abstract Simple and sensitive Spectrophotometric methods and a densitometric thin layer chromatographic method (TLC) are developed and validated for simultaneous determination of binary mixture of metformin hydrochloride (MET) and canagliflozin (CFZ) in combined dosage form. Three spectrophotometric methods manipulating ratio spectra namely ratio subtraction, ratio difference and derivative ratio are used for the determination of MET in the presence of CFZ without preliminary separation, while CFZ is directly determined by measuring its absorbance at λmax 290 nm. The calibration curves follow Beers law in the concentration range of 1 - 20 and 1 - 30 μg/mL for MET and CFZ respectively. A simple TLC method is developed where separation is performed on TLC silica gel plates 60F254 using toluene: Methylene chloride: methanol: water: glacial acetic acid in the volume ratio (20:15:15:1:0.25) as a mobile phase. Rf values are 0.55 ± 0.05 for CFZ and 0.21 ± 0.03 for MET, the linearity ranges are 0.3-4.5 and 0.5-5.5 μg/band for CFZ and MET respectively. The developed methods are successfully applied for the simultaneous determination of MET and CFZ in bulk and pharmaceutical formulation.

Novel Approach for the Simultaneous Determination of Carbinoxamine Maleate, Pholcodine, and Ephedrine Hydrochloride Without Interference from Coloring Matter in an Antitussive Preparation Using Smart Spectrophotometric Methods

The presence of coloring matters in syrups usually interferes with the spectrophotometric determination of active pharmaceutical ingredients. A novel approach was introduced to eliminate the interference of sunset yellow (coloring matter) in Cyrinol syrup. Smart, simple, accurate, and selective spectrophotometric methods were developed and validated for the simultaneous determination of a ternary mixture of carbinoxamine maleate, pholcodine, and ephedrine hydrochloride in syrup. Four of the applied methods used ratio spectra: successive derivative subtraction coupled with constant multiplication, successive derivative of ratio spectra, ratio subtraction coupled with ratio difference, and ratio spectra continuous wavelet transforms zero-crossing. In addition, a method that was based on the presence of an isosbestic point, the amplitude summation method, was also established. A major advantage of the proposed methods is the simultaneous determination of the mentioned drugs without prior separation steps. These methods were successfully applied for the determination of laboratory-prepared mixtures and a commercial pharmaceutical preparation without interference from additives, thus proving the selectivity of the methods. No significant difference regarding both accuracy and precision was observed upon statistical comparison of the results obtained by the proposed methods with each other and with those of official or reported ones.