Novel HPTLC method for simultaneous estimation from ternary mixture of chlorpheniramine maleate, dextromethorphan hydrobromide and phenylephrine hydrochloride in syrup formulations.

OBJECTIVES: A synergic antihistamine, cough suppressant, and decongestant combination of chlorpheniramine, dextromethorphan, and phenylephrine is used to treat acute respiratory infections caused by seasonal viruses. The effective qualitative and quantitative methods require the simultaneous measurement of a ternary combination in the pharmaceutical syrup dosage form. Therefore, a new, simple, fast and robust high performance thin layer chromatographic (HPTLC) method has been developed and validated for chlorpheniramine maleate (CPM), dextromethorphan hydrobromide (DEXO) and phenylephrine hydrochloride (PE). MATERIAL AND METHODS: The chromatographic separation was carried out on precoated aluminium plates with silica gel 60 F254 as the stationary phase. Mobile phase used was chloroform: methanol: ammonia (2.5:7.5:0.3, v/v/v) for proper separation. The detection was carried out at 270nm wavelength in absorbance mode. Developed method was validated as per International Council for Harmonization (ICH) Q2 (R1) guideline. RESULTS: The linearity range is 400 to 1400ng/band for CPM, 3000 to 11500ng/band for DEXO and 1000 to 3500ng/band for PE with correlation coefficient ≥ 0.995. The consistent lower values of relative standard deviation (RSD, %) for precision and robustness study indicate the method reliability. The percent recovery ranged from 97.82 to 102.03% indicates the good accuracy of the method. CONCLUSION: The proposed method was complying for the analytical method validation parameters suggested by the ICH Q2 (R1) guideline. The method was found to be simple, rapid and reliable for the simultaneous estimation of CPM, DEXO and PE from its pharmaceutical syrup dosage form. The method was successfully applied to quantify these analytes from the several pharmaceutical syrup dosage form.

Validated Liquid Chromatography-Tandem Mass Spectroscopic Method for Simultaneous Determination of Certain Drugs Used in Cataract Surgery in Rabbit Aqueous Humor.

A sensitive, selective, accurate and precise ultra-high performance liquid chromatography-Tandem mass spectrometry (MS/MS) method was developed and validated for the simultaneous determination of drugs used as eye drops in cataract surgery in aqueous humor. Cataract surgery requires a powerful mydriatic eye drops combination such as cyclopentolate hydrochloride and phenylephrine hydrochloride to dilate the pupil and facilitate eye lens replacement and also requires strong fluoroquinolone antibiotic such as lomefloxacin hydrochloride. The method was performed with positive ion electrospray ionization and the analytes were quantified and monitored on a triple quadrupole mass spectrometer using multiple reaction monitoring scanning mode. Liquid-liquid extraction was used for the purification and preconcentration of analytes from rabbit aqueous humor matrix. Chromatographic elution was performed using an Phenomenex Luna® C18 (150 mm × 2.1 mm, 1.6 µm) column and moxifloxacin hydrochloride as internal standard with a mobile phase consisting of methanol:water:formic acid (70:29:1, by volume) at flow rate of 0.2 mL/min. Satisfactory results regarding linearity, recovery, stability, accuracy and precision of the analytes were obtained. Full validation of the procedure was performed according to the US Food and Drug Administration guidance for industry: bioanalytical method validation and European Medicines Agency (EMA) guideline on bioanalytical method validation.

Analytical investigation of ternary mixture of phenylephrine hydrochloride, dimetindene maleate and benzalkonium chloride using validated stability indicating HPLC-DAD method.

A stability-indicating high performance liquid chromatography method with diode array detection (HPLC-DAD) was developed and validated for simultaneous determination of phenylephrine hydrochloride (PHR), dimetindene maleate (DMD) and benzalkonium chloride (BZM) in nasal drops and gel dosage forms. Effective liquid chromatographic separation was accomplished by employing Venusil XBP Cyano column (4.6 × 250 mm, 5 µm particle size) with gradient elution of the mobile phase consisting of buffer solution of potassium dihydrogen phosphate (0.025 M) and sodium 1-butane sulfonate (SBS) (0.025 M) (adjusted to pH 6.0) and acetonitrile. Peak areas of PHR, DMD and BZM at 271, 256 and 206 nm, respectively were measured and correlated to their concentrations. Peaks of PHR and DMD eluted at retention times 3.76 and 9.06 min, respectively, while BZM eluted as a couple of peaks at 11.88 and 12.51 min. The proposed HPLC procedure was carefully validated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. The linearity range for both PHR and BZM was 10-400 µg/mL and DMD was 5-300 µg/mL with correlation coefficients >0.9999. The studied compounds were subjected to stress conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal degradation. Good resolution of the three compounds from their forced degradation products proves specificity and stability-indicating merits of the proposed method. In addition, resolution of the three drugs under investigation from some pharmaceutical compounds of different medicinal categories showed the high specificity of the described method.

USB multiplex analyzer employing screen-printed silver electrodes on paper substrate; A developed design for dissolution testing.

Multiplex ion analyzers have been introduced recently for the assay of several inorganic ions, whilst electrochemists have extensively employed screen printed sensors for pharmaceutical analyses. This work aims to develop a USB pluggable sensor with a user-friendly design for multiplex analysis of oppositely charged co-formulated organic ions. The miniaturized screen-printed electrode was developed using silver ink on paper substrate. A compact sensor design was attained by including three electrodes, a single reference electrode along with an indicator electrode for each of the determined ions. Optimized PVC membranes were drop-casted over each of the indicator electrodes for the determination of phenylephrine HCl (PHE) and ibuprofen (IBU). The proposed multiplex potentiometric sensors exhibit Nernstian slopes of 59.2 ±â€¯0.26 and -56.8 ±â€¯0.16 mV/decade for PHE and IBU, respectively, with respective detection limits of 1.6 × 10-7 and 6.53 × 10-8 mol L-1. The fast and stable response of the developed sensor enabled the real-time monitoring of the combined dosage form dissolution. The dissolution profiles obtained by this potentiometric analyzer and an off-line separation technique were compared favourably, albeit our proposed in-line sensor reduced waste and time of analysis. The developed method successfully complies with the most demanding stipulations of green analytical chemistry.

Synchronous spectrofluorometric methods for simultaneous determination of diphenhydramine and ibuprofen or phenylephrine in combined pharmaceutical preparations.

Simple and rapid synchronous fluorometric methods were adopted and validated for the simultaneous analysis of a binary mixture of diphenhydramine (DIP) and ibuprofen (IBU) (Mix I) or DIP and phenylephrine (PHE) (Mix II) in their co-formulated pharmaceuticals without prior separation. Analysis of Mix I is based on the measurement of the peak amplitudes (D1 ) of synchronous fluorescence intensities at 265.1 nm for DIP and 260 nm for IBU. The relationship between the concentration and the amplitude of the first-derivative synchronous fluorescence spectra showed good linearity over the concentration ranges 0.50-10.00 µg ml-1 and 0.50-7.90 µg ml-1 for DIP and IBU, respectively. Analysis of Mix II was based on measurement of the peak amplitude (D1 ) synchronous fluorescence intensities at 230 nm for DIP and at 253.9 nm for PHE. Moreover, for Mix II, the peak amplitude (D2 ) synchronous fluorescence intensities were measured at 227.9 nm for DIP and at 264.9 nm for PHE. Calibration plots were rectilinear over the concentration range 0.30-3.50 µg ml-1 and 0.03-0.75 µg ml-1 for DIP and PHE, respectively. The proposed methods were successfully applied to determine the studied compounds in pure form and in pharmaceutical preparations.

Evaluation of the bioequivalence of two formulations containing the combination of 400 mg of acetaminophen (paracetamol), 4 mg of phenylephrine and 4 mg of chlorpheniramine in capsules: open-label, three-way crossover study, partially replicated in healthy volunteers of both sexes

This study was carried out in order to compare the relative bioavailability of two different formulations containing 400 mg of acetaminophen + 4 mg of phenylephrine hydrochloride + 4 mg of chlorpheniramine maleate, Test formulation (Cimegripe®) and Reference formulation (Resfenol®) in 84 healthy volunteers of both sexes under fasting conditions. The study was conducted in a single dose, randomized, open-label, crossover 3-way and partially replicated. The tolerability was evaluated by the monitoring of adverse events and vital signs, results of clinical and laboratory tests. Plasma concentrations were quantified by validated bioanalytical methods using the ultra-performance liquid chromatography coupled to tandem mass spectrometry. The Cmax, Tmax, AUC0-t, AUC0-inf, T1/2 and Kel pharmacokinetic parameters were calculated from these obtained concentrations. The 90% confidence intervals were constructed for the ratio reference/test from the geometric average of the Cmax and AUC parameters which were comprised between 80% and 125%. Only the Cmax parameter of the phenylephrine was applied the scaled average bioequivalence due to the intraindividual coefficient of variation > 30% obtained, thus extending the acceptance limits of the interval. It can be concluded that the two formulations were bioequivalent in terms of rate and absorption extent and thus interchangeable

Pd nanoparticles decorated poly-methyldopa@GO/Fe3O4 nanocomposite modified glassy carbon electrode as a new electrochemical sensor for simultaneous determination of acetaminophen and phenylephrine.

In this study, a new nanocomposite consists of magnetic graphene oxide (GO/Fe3O4), poly-methyldopa (PMDA) and Pd nanoparticle was prepared and utilized for constructing an electrochemical sensor to determine acetaminophen (AC) and phenylephrine (PHE). The structure of nanocomposite has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The effects of various parameters with effective on the sensor response are optimized. In a range, 5 nM to 2.5 µM for AC and 50 nM to 3 µM for PHE the designed sensor had a response linearly reliant on the AC and PHE concentration respectively by differential pulse voltammetry. Also, the limits of detection for AC and PHE with this sensor were 2.1 nM and 7.8 nM, respectively. It successfully employed for the determination of trace amounts of the AC and PHE in pharmaceutical combination and human serum samples.

Robust Chromatographic Methods for the Analysis of Two Quaternary Mixtures Containing Paracetamol, Codeine, Guaifenesin and Pseudoephedrine or Phenylephrine in their Dosage Forms.

Two simple validated and highly selective methods for analysis of paracetamol, codeine, guaifenesin and pseudoephedrine or phenylephrine quaternary mixtures were developed. The first method is a high performance liquid chromatography with diode array detection method where separation was successful using Agilent C18 (150 × 4.6 mm) column, gradient elution of phosphate buffer pH 3, methanol and acetonitrile and diode-array detection at 210 nm. The second method is a HPTLC method followed by densitometric measurement of the spots at 257 nm. Separation was carried out on Merck HPTLC aluminum sheets of silica gel using methylene chloride: methanol: glacial acetic acid: ammonia (17.8: 1.68: 0.4: 0.12, v/v) mobile phase. The methods were applied successfully for analysis of both quaternary mixtures in laboratory-prepared tablets and also validated in regards to linearity, precision, accuracy, sensitivity and stability.

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.

Determination of Ibuprofen and Phenylephrine in Tablets by High-Performance Thin Layer Chromatography and in Plasma by High-Performance Liquid Chromatography with Diode Array Detection.

Two chromatographic methods (high performance thin layer chromatography (HPTLC) and high performance liquid chromatography-diode array detector (HPLC-DAD)), were addressed for the analysis of a mixture consisted of phenylephrine hydrochloride and ibuprofen in two forms bulk and their combined dosage form. This binary mixture is considered to be a challenging one as the two drugs differ greatly in their chemical and physical properties. Not only this affects their simultaneous analysis, but also hinders their simultaneous extraction from biological fluids as plasma. That is the reason the literature lacks any report for the simultaneous extraction and analysis of these drugs from biological fluids. The concentration ranges of both drugs were 0.1-2.5 µg/spot and 0.1-100 µg/mL by HPTLC and HPLC, respectively. Not only was the HPLC-DAD method applied to the investigated drugs determination in pharmaceutical preparations, but also in spiked human plasma. Extensive study was conducted to optimize their simultaneous extraction from plasma as it was a crucial step for the in vivo analysis. The results obtained by proposed methods and a reference one were statistically comparable by analysis of variance test. No significant difference was recorded between the mean percent levels determined by the proposed methods and the reference one.

Application of Capillary Zone Electrophoresis Coupled with a Diode Array Detector (CZE-DAD) for Simultaneous Analysis of Ibuprofen and Phenylephrine.

Background: A validated method based on capillary zone electrophoresis coupled with a diode array detector (CZE-DAD) was investigated for analyzing binary mixture of ibuprofen (IBU) and phenylephrine (PHE) in their bulk and combined dosage form. Objective: This binary mixture is a challenging one as IBU is acidic and PHE is alkaline, which may affect their simultaneous analysis using CZE. The literature lacks any CZE report for IBU and PHE simultaneous analysis. Methods: Fused silica capillary (85 cm × 75 µm id) was used, and the electrolyte was a 50 mM borate buffer adjusted to pH 11 with 0.5 M NaOH. Results: The concentration ranges were 5-200 and 5-100 µg/mL for IBU and PHE, respectively, using CZE. High efficiency was achieved (N > 92990). Reasonable migration time (tm) was attained (tm< 8.5 min). Conclusions: Although the results obtained by the proposed CZE method and reported HPLC method were statistically comparable, the proposed method showed lower linearity ranges, higher efficiency, and a more reasonable run time. Highlights: CZE-DAD was used for the analysis of IBU and PHE in bulk and tablets, as no report was found for their determination using CZE. Binary mixture is challenging due to differences in chemical and physical properties. A detailed discussion of electrophoretic parameters optimization is included. Confirmation of peak purity was attained using DAD.

Application of derivative emission fluorescence spectroscopy for determination of ibuprofen and phenylephrine simultaneously in tablets and biological fluids.

Two sensitive, rapid, and accurate derivative emission spectrofluorimetric methods applying zero crossing techniques were developed for simultaneous determination of binary mixtures of ibuprofen (IBU) and phenylephrine hydrochloride (PHE) in pure powder, synthetic mixture and combined tablets. The proposed methods were performed via measuring the intersected drug derivative amplitude of one drug at the zero crossing points for the other one and vice versa. The two methods rely on the measurement of the combined drugs native fluorescence after excitation at 270 nm in methanol directly, followed by differentiation using first (D1) and second derivative (D2) techniques. Applying the D1, IBU was measured quantitatively at 293.1 nm at zero crossing of PHE, on the other side; PHE was measured quantitatively at 300.7 nm at zero crossing of IBU. By the same way, applying the D2, the wavelengths selected were 303.5 nm for IBU and 312.9 nm for PHE. The concentration plots of derivative fluorescence intensity were rectilinear over the range of 0.5-10 µg/mL and 0.025-0.5 µg/mL for IBU and PHE, respectively. The results obtained with average % recoveries ±â€¯RSD are 99.73 ±â€¯0.72 (IBU, D1), 99.49 ±â€¯0.95 (PHE, D1), 99.79 ±â€¯0.47 (IBU, D2), and 99.88 ±â€¯0.34 (PHE, D2) were in good agreement with the comparison method. The proposed methods offer high sensitivity that enable direct analysis of IBU and PHE in spiked human plasma. The proposed methods were entirely validated in terms of ICH guidelines.

Late cardiac perconditioning by phenylephrine in an isolated rat heart model is mediated by mitochondrial potassium channels

The present study was designed to investigate the effect of early and late administration of phenylephrine during ischemia against regional ischemia-reperfusion injuries in an isolated rat heart model. All animals were randomly divided into experimental groups: (I) IR (Ischemic/ reperfusion): the hearts underwent 35 min of regional ischemia followed by 60 min of reperfusion; (II) 5HD-IR-0: the hearts were perfused for 5 min with 5HD (5-hydroxydecanoate, specific mKATP channel blocker, 100 µM) at the onset of regional ischemia; (III) 5HD-IR-20: the hearts were perfused for 5 min with 5HD 20 min after regional ischemia; (IV) PE-IR-10: the hearts were perfused for 5 min with phenylephrine 10 min after regional ischemia; (V) PE-IR-30: the hearts were perfused for 5 min with phenylephrine (100 µM) 30 min after regional ischemia; (VI) PE-5HD-IR-10 group: the hearts were perfused for 5 min with 5HD at the onset of regional ischemia after which phenylephrine was administrated as in group IV; and (VII) PE-5HD-IR-30: the hearts were perfused for 5 min with 5HD 20 min after the ischemia and then phenylephrine was administrated as in group V. The hemodynamic parameters were recorded throughout the experiment. Ischemia-induced arrhythmias, myocardial infarct size (IS), creatin kinase-MB isoenzyme (CK-MB), plasma lactate dehydrogenase (LDH) activities, and coronary blood flow (CBF) were measured in all animals. Perfusion of phenylephrine 30 min after the regional ischemia curtailed the myocardial infarct size, reduced CK-MB, and improved cardiac function and CBF. Administration of 5HD 30 min after the ischemia abolished cardioprotective effects of phenylephrine in the late phase. These results suggest the involvement of mKATP in the mechanism of phenylephrine-induced late preconditioning.

High sensitivity deep-UV LED-based z-cell photometric detector for capillary liquid chromatography.

A new high sensitivity deep-UV LED photometric detector with a z-type flow cell (45 nL or 180 nL) for miniaturised and portable capillary liquid chromatography (LC) was designed and fabricated to overcome sensitivity limitations due to short pathlength in on-capillary detectors. The new detector has a 10 mm geometric pathlength and uses high intensity light-emitting diodes (LED) as light sources in the deep-UV range (254 nm and 280 nm). No optical reference was necessary due to the low drift in the signal. Stray light was minimized by the use of an adjustable slit with a 0.5 mm pinhole. The direct relationship between absorbance and concentration was obtained using dichromate to evaluate the sensitivity and the linearity range of the detector. Performance of the miniaturised version was compared with that obtained from a commercial benchtop detector for capillary LC under the same conditions using the same optical z-cell. The miniaturised version exhibited a superior performance across all parameters, including 3 times higher effective pathlength, 4 times higher upper limit of detector linearity, and 2-5 times lower stray light levels. An application of the new detector was shown with the detection of l-dopa, l-tyrosine, norfenefrine, phenylephrine and tyramine, separated using capillary LC. The baseline noise level recorded was as low as 3.9 µAU. Further, the detector was applied in a miniaturised capillary LC for the indirect detection of common inorganic anions. In comparison to an on-capillary LED detector applied under similar chromatographic conditions, there was a 50 times higher signal to noise (S/N) ratio.

Derivative synchronous spectrofluorimetry: Application to the analysis of two binary mixtures containing codeine in dosage forms.

Two binary mixtures containing codeine (COD) with either ibuprofen (IBU), mixture 1, or with phenylephrine hydrochloride (PE), mixture 2, were analyzed using three simple eco-friendly spectrofluorimetric methods without the need to a prior separation step. The first method is derivative emission spectrofluorimetry using λex = 236 nm and 275 nm for mixtures 1 and 2, respectively. The second method is constant-wavelength synchronous spectrofluorimetry using ∆λ = 100 nm and 60 nm for mixtures 1 and 2, respectively. The last method is constant-energy synchronous spectrofluorimetry where a wave number interval of -7000 cm-1 was used for the analysis of the two binary mixtures. All measurements were performed in acetate buffer pH 5 and thus no toxic volatile solvents were used increasing method greenness. High sensitivity was attained for the three studied drugs where the lower limits of quantitation of COD, IBU and PE reached 0.064, 0.512 and 0.087 µg/mL, respectively. Analysis of the two binary mixtures in their tablet and liquid dosage forms was performed with good accuracy and precision using the developed methods. The results of the proposed and reported methods were statistically evaluated using one-way ANOVA test and no significant difference among them was obtained. In addition, all aspects of ICH guidelines on analytical method validation were conducted.

Development and Validation of Eco-Friendly Liquid Chromatographic and Spectrophotometric Methods for Simultaneous Determination of Coformulated Drugs: Phenylephrine Hydrochloride and Prednisolone Acetate.

Five simple, sensitive, and eco-friendly LC and UV spectrophotometric methods have been developed for the simultaneous determination of phenylephrine hydrochloride (PHE) and prednisolone acetate (PRD) in their combined dosage form. The first method was reversed-phase (RP) LC using methanol-water-heptane-1-sulfonic acid sodium salt (75 + 25 + 0.1, v/v/w) as a mobile phase. Separation was achieved using an XSelect HSS reversed-phase C18 analytical column (250 × 4.6 mm, 5µm). The flow rate was 1.0 mL/min and UV detection was done at 230 nm. Quantification was achieved over the concentration ranges of 5-50 µg/mL for PHE and 2-90 µg/mL for PRD. Four spectrophotometric methods were proposed, namely dual wavelength, first derivative of ratio spectra, ratio difference, and mean-centering of ratio spectra. Linearity was observed in the concentration ranges of 10-120 and 5-35 µg/mL for PHE and PRD, respectively, for the spectrophotometric methods. Green solvents were used in the proposed methods because they play a vital role in the analytical methods' influence on the environment. The suggested methods were validated regarding linearity, accuracy, and precision according to the International Conference on Harmonization guidelines, with satisfactory results. These methods could be used as harmless substitutes for routine analysis of the mentioned drugs, with no interference from excipients.

Chromatographic Determination of Cyclopentolate Hydrochloride and Phenylephrine Hydrochloride in the Presence of Their Potential Degradation Products.

Two sensitive, selective, and precise stability-indicating methods have been developed for the simultaneous determination of the active pharmaceutical ingredients cyclopentolate hydrochloride (CLO) and phenylephrine hydrochloride (PHE) in their pure forms and in the presence of their degradation products. The methods were applied for the determination of CLO and PHE in a pharmaceutical formulation. Method A was based on isocratic elution HPLC determination. Separation was achieved using a Waters Spherisorb ODS2 C18 analytical column (5 µm particle size) and a mobile phase of 0.1% heptane-1-sulphonic acid sodium salt in methanol-water (80 + 20, v/v). The flow rate was 1.0 mL/min and detection was performed at 210 nm. Method B was an HPTLC- densitometric method using HPTLC silica gel 60 F254 plates and an optimized mobile phase of ethyl acetate-methanol-ammonia (8 + 2 + 0.1, v/v/v). The separated spots were densitometrically scanned at 210 nm. Polynomial equations were used for regression. The developed methods are suitable for the determination of CLO and PHE in their binary mixture and in the presence of their corresponding degradation products. The two methods were validated in compliance with International Conference on Harmonization guidelines and successfully applied for the determination of CLO and PHE as synthetically prepared in laboratory mixtures and in the presence of their possible degradation products. CLO alkaline degradation products were stated as potential impurities in British Pharmacopoeia. The degradation products were separated and identified by mass spectra. Postulation of a PHE oxidative degradation pathway was suggested. The obtained results were statistically analyzed and compared with those obtained by applying the official methods for both drugs.

Direct detection of phenylephrine 3-O-sulfate in LS180 human intestinal cells using a novel hydrophilic interaction liquid chromatography (HILIC) assay.

The efficacy of phenylephrine (PE) is controversial due to its extensive pre-systemic metabolism through sulfation to form phenylephrine-3-O-sulfate (PES). Hence quantitation of PES is important in order to study the metabolism of PE. There are no published methods available for direction detection of PES. We have developed and validated a hydrophilic interaction liquid chromatography (HILIC) method for the direct detection of PES and simultaneous detection of PE to study the enzyme kinetics and metabolism of PE to enable approaches to reduce the presystemic metabolism of PE. This is the first method which facilitates direct detection of PES and simultaneous detection of PE using a zwitterionic HILIC column with improved sensitivity in a single short run. The observed quantitative ranges of our method for PE and PES were 0.39-200µM and 0.0625-32µM (respectively) with a run time of 6.0min. The method was applied to the determination of PE and PES in LS180 human intestinal cell line, recombinant enzymes and human intestinal cytosol (HIC).

Development and Validation of Chemometric-Assisted Spectrophotometric Methods for Simultaneous Determination of Phenylephrine Hydrochloride and Ketorolac Tromethamine in Binary Combinations.

The present work describes new spectrophotometric methods for the simultaneous determination of phenylephrine hydrochloride and ketorolac tromethamine in their synthetic mixtures. The applied chemometric techniques are multivariate methods including classical least squares, principal component regression, and partial least squares. In these techniques, the concentration data matrix was prepared by using the synthetic mixtures containing these drugs dissolved in distilled water. The absorbance data matrix corresponding to the concentration data was obtained by measuring the absorbances at 16 wavelengths in the range 244-274 nm at 2 nm intervals in the zero-order spectra. The spectrophotometric procedures do not require any separation steps. The accuracy, precision, and linearity ranges of the methods have been determined, and analyzing synthetic mixtures containing the studied drugs has validated them. The developed methods were successfully applied to the synthetic mixtures and the results were compared to those obtained by a reported HPLC method.

Development and validation of a generic high-performance liquid chromatography for the simultaneous separation and determination of six cough ingredients: Robustness study on core-shell particles.

A generally applicable high-performance liquid chromatographic method for the qualitative and quantitative determination of pharmaceutical preparations containing phenylephrine hydrochloride, paracetamol, ephedrine hydrochloride, guaifenesin, doxylamine succinate, and dextromethorphan hydrobromide is developed. Optimization of chromatographic conditions was performed for the gradient elution using different buffer pH values, flow rates and two C18 stationary phases. The method was developed using a Kinetex® C18 column as a core-shell stationary phase with a gradient profile using buffer pH 5.0 and acetonitrile at 2.0 mL/min flow rate. Detection was carried out at 220 nm and linear calibrations were obtained for all components within the studied ranges. The method was fully validated in agreement with ICH guidelines. The proposed method is specific, accurate and precise (RSD% < 3%). Limits of detection are lower than 2.0 µg/mL. Qualitative and quantitative responses were evaluated using experimental design to assist the method robustness. The method was proved to be highly robust against 10% change in buffer pH and flow rate (RSD% < 10%), however, the flow rate may significantly influence the quantitative responses of phenylephrine, paracetamol, and doxylamine (RSD% > 10%). Satisfactory results were obtained for commercial combinations analyses. Statistical comparison between the proposed chromatographic and official methods revealed no significant difference.