An eco-friendly stability-indicating spectrofluorimetric method for the determination of two anticancer stereoisomer drugs in their pharmaceutical preparations following micellar enhancement: Application to kinetic degradation studies

A new rapid and highly sensitive stability-indicating spectrofluorimetric method was developed for the determination of two stereoisomers anticancer drugs, doxorubicin (DOX) and epirubicin (EPI) in pure form and in pharmaceutical preparations. The fluorescence spectral behavior of DOX and EPI in a sodium dodecyl sulfate (SDS) micellar system was investigated. It was found that the fluorescence intensity of DOX and EPI in an aqueous solution of phosphate buffer pH4.0 and in the presence of SDS was greatly (about two fold) enhanced and the mechanism of fluorescence enhancement effect of SDS on DOX was also investigated. The fluorescence intensity of DOX or EPI was measured at 553nm after excitation at 497nm. The plots of fluorescence intensity versus concentration were rectilinear over a range of 0.03-2μg/mL for both DOX and EPI with good correlation coefficient (r>0.999). High sensitivity to DOX and EPI was attained using the proposed method with limits of detection of 10 and 9ng/mL and limits of quantitation of 29 and 28ng/mL, for DOX and EPI, respectively. The method was successfully applied for the determination of DOX and EPI in biological fluids and in their commercial pharmaceutical preparations and the results were concordant with those obtained using a previously reported method. The application of the proposed method was extended to stability studies of DOX following different forced degradation conditions (acidic, alkaline, oxidative and photolytic) according to ICH guidelines. Moreover, the kinetics of the alkaline and oxidative degradation of DOX was investigated and the apparent first-order rate constants and half-life times were calculated.

Enhanced spectrophotometric determination of two antihyperlipidemic mixtures containing ezetimibe in pharmaceutical preparations

Two spectrophotometric methods are presented for the simultaneous determination of ezetimibe/simvastatin and ezetimibe/atorvastatin binary mixtures in combined pharmaceutical dosage forms without prior separation. The first is the derivative ratio method where the amplitudes of the first derivative of the ratio spectra ((1) DD) at 299.5 and 242.5 nm were found to be linear with ezetimibe and simvastatin concentrations in the ranges 0.5-20 µgml(-1) and 1-40 µgml(-1) , respectively, whereas the amplitudes of the first derivative of the ratio spectra ((1) DD) at 289.5 and 288 nm were selected to determine ezetimibe and atorvastatin in the concentration ranges 5-50 µgml(-1) and 1-40 µgml(-1) , respectively. The second is the H-point standard additions method; absorbances at the two pairs of wavelengths, 228 and 242 nm or 238 and 248 nm, were monitored while adding standard solutions of ezetimibe or simvastatin, respectively. For the analysis of ezetimibe/atorvastatin mixture, absorbance values at 226 and 248 nm or 212 and 272 nm were monitored while adding standard solutions of ezetimibe or atorvastatin, respectively. Moreover, differential spectrophotometry was applied for the determination of ezetimibe in the two mixtures without any interference from the co-existing drug. This was performed by measurement of the difference absorptivities (ΔA) of ezetimibe in 0.07 M 30% methanolic NaOH relative to that of an equimolar solution in 0.07 M 30% methanolic HCl at 246 nm. The described methods are simple, rapid, precise and accurate for the determination of these combinations in synthetic mixtures and dosage forms.

Recent Advances and Applications of Microfluidic Capillary Electrophoresis: A Comprehensive Review (2017-Mid 2019)

Microfluidic capillary electrophoresis (MCE) is the novel technique resulted from the CE mininaturization as planar separation and analysis device. This review presents and discusses various application fields of this advanced technology published in the period 2017 till mid-2019 in eight different sections including clinical, biological, single cell analysis, environmental, pharmaceuticals, food analysis, forensic and ion analysis. The need for miniaturization of CE and the consequence advantages achieved are also discussed including high-throughput, miniaturized detection, effective separation, portability and the need for micro- or even nano-volume of samples. Comprehensive tables for the MCE applications in the different studied fields are provided. Also, figure comparing the number of the published papers applying MCE in the eight discussed fields within the studied period is included. The future investigation should put into consideration the possibility of replacing conventional CE with the MCE after proper validation. Suitable validation parameters with their suitable accepted ranges should be tailored for analysis methods utilizing such unique technique (MCE).

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 λ_ex = 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.

Hantzsch pre-column derivatization for simultaneous determination of alendronate sodium and its pharmacopoeial related impurity: Comparative study with synchronous fluorometry using fluorescamine

High performance liquid chromatographic (HPLC) method with a pre-column derivatization based on Hantzsch condensation reaction was applied for simultaneous determination of alendronate sodium (ALN) and its main related impurity, 4-Aminobutanoic acid (ABA) at its pharmacopeial limit. The separation of colored condensation products of ALN and ABA were achieved on Agilent Zobrax Eclipse SB-C18 analytical column (250 × 4.6 mm, 5 μm) using a mobile phase composed of acetonitrile–0.1 M acetate buffer, pH 5.0 (15:85, v/v). The flow rate was 1 mL min⁻¹. The detection was carried out at 340 nm using photo-diode array detector. Peak areas were used for the linear regression line in the range of 10–500 and 0.2–40 μg mL⁻¹ for ALN and ABA, respectively. Different conditions for the optimization of the derivatization reactions as well as for the HPLC measurement were studied. The proposed method was validated for linearity, precision, accuracy, specificity and robustness. This method was used to check the purity of ALN in the presence of ABA (related impurity) at the pharmacopeial limit (0.5%). For comparison purpose, another method was proposed which involves synchronous fluorescence measurement after ALN reaction with fluorescamine. In this method, the third derivative synchronous spectra were estimated as peak to peak measurement from 339 to 370 nm for ALN determination with LOD and LOQ of 24 and 73 ng mL⁻¹, respectively, showing very high sensitivity. Both methods have been applied for determination of the alendronate sodium (ALN) in bulk and pharmaceutical preparations without interference of additives in tablets or oral solution.

Investigation of the spectrofluorimetric behavior of azelastine and nepafenac: Determination in ophthalmic dosage forms

The first spectrofluorimetric report investigating the fluorimetric behavior of the antihistaminic drug, azelastine (AZEL), and the non-steroidal anti-inflammatory drug, nepafenac (NEP), either in bulk or in their dosage forms, eye drops and ophthalmic suspension. After a full investigation of the factors that may influence their spectrofluorimetric behavior: pH, different organized media and organic solvents, the optimum factors were set in order to enable the analysis of each drug with maximum sensitivity. The AZEL spectrofluorimetric analysis was set at 286/364 (λ_ex/λ_em) in distilled water while for NEP, the analysis was set at 228/303 (λ_ex/λ_em) in methanol. The linearity range for AZEL was from 0.1 to 1.5 μg/mL while that of NEP was from 0.2 to 1.5 μg/mL. The linearity yielded good regression parameters with low LOD (0.022 and 0.032 μg/mL for AZEL and NEP, respectively) and LOQ (0.073 and 1.08 μg/mL for AZEL and NEP, respectively) when compared with those obtained from many previous spectroscopic and chromatographic reports in literature. The method was ICH validated and was applied to the analysis of AZEL and NEP with good selectivity regarding the inactive ingredients.

Fourier convolution versus derivative spectrophotometry: Application to the analysis of two binary mixtures containing tamsulosin hydrochloride as a minor component

Simple and rapid spectrophotometric methods are described for determination of two mixtures of tamsulosin (TM), as minor component, with either solifenacin (SL) or tolterodine (TL). The proposed methods involve treatment of the absorbance ratio spectra or zero order spectra by derivative or discrete Fourier function. TM and TL mixture could not be resolved by manipulation of their zero order spectra due to the strong overlap between both spectra and only derivative or Fourier function coefficients of ratio spectra could resolve their spectra. TM and SL mixture was fully resolved by the manipulation of both ratio and zero order spectra. The values of the derivative or the Fourier function coefficients of ratio spectra and/or zero order spectra, at either peak or trough points, were correlated to the concentration of each drug in each mixture. Calibration graphs were linear in ranges 2.5-40 and 30-500μg.mL^-1 using derivative ratio and Fourier function ratio, 5-40 and 80-600μg.mL^-1 using direct derivative and 2.5-40 and 30-300μg.mL^-1 using direct Fourier function for TM and SL, respectively. The plots of derivative ratio amplitude and the Fourier function ratio coefficient versus concentration were linear over ranges 2.5-20 and 25-250μg.mL^-1 for TM and TL, respectively. Higher sensitivity as indicated by lower values of detection and quantitation limits were obtained using Fourier convoluted spectra (ratio or zero order) compared to derivative methods. All validation aspects per ICH guidelines are included. The proposed methods were also applied for the studied drugs assay in their tablets and capsules.

Simultaneous determination of methocarbamol and aspirin in presence of their pharmacopeial-related substances in combined tablets using novel HPLC-DAD method

Objective and Significance: Methocarbamol (MET) and aspirin (ASP) are widely used as a muscle relaxant combination. The USP reports guaifenesin (GUA) and salicylic acid (SAL) as related substances and hydrolytic products of MET and ASP, respectively. This work aimed at developing and validating a simple and sensitive RP-HPLC method for the determination of both drugs as well as their related substances (at their pharmacopeial limits) in their bulk powders, laboratory prepared mixtures, and MET-ASP combined tablets. Methods and Results: Chromatographic separation was achieved in less than 9 min with the required resolution, peak symmetry, and accuracy on C₁₈ column using isocratic elution system of diluted acetic acid (pH 3.2): acetonitrile at the ratio of 79: 21, v/v, at a flow rate of 1 mL/min. Detection was achieved with photodiode array at 233 nm for MET, GUA, and SAL and at 273 nm for ASP. The developed method has been validated as per ICH guidelines and the calibration plots were linear over the concentration ranges of 2-150, 0.4-30, 25-450, and 0.2-27 μg/mL for MET, GUA, ASP, and SAL, respectively. Conclusion: The optimized method proved to be specific, robust and precise for the quality control of the studied drugs in pharmaceutical preparations to ascertain that their related substances are not exceeding the permitted pharmacopeial limits.

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.

Analytical Methodologies for the Estimation of Oxazolidinone Antibiotics as Key Members of anti-MRSA Arsenal: A Decade in Review

Gram-positive bacterial infections are among the most serious diseases related with high mortality rates and huge healthcare costs especially with the rise of antibiotic-resistant strains that limits treatment options. Thus, development of new antibiotics combating these multi-drug resistant bacteria is crucial. Oxazolidinone antibiotics are the only totally synthetic group of antibiotics that showed activity against multi-drug resistant Gram positive bacteria including MRSA because of their unique mechanism of action in targeting protein synthesis. This group include approved marketed members (tedizolid, linezolid and contezolid) or those under development (delpazlolid, radezolid and sutezolid). Due to the significant impact of this class, larger number of analytical methods were required to meet the needs of both clinical and industrial studies. Analyzing these drugs either alone or with other antimicrobial agents commonly used in ICU, in the presence of pharmaceutical or endogenous biological interferences, or in the presence of matrix impurities as metabolites and degradation products poses a big analytical challenge. This review highlights current analytical approaches published in the last decade (2012-2022) that dealt with the determination of these drugs in different matrices and discusses their advantages and disadvantages. Various techniques have been described for their determination including chromatographic, spectroscopic, capillary electrophoretic and electroanalytical methods. The review comprises six sections (one for each drug) with their related tables that depict critical figures of merit and some experimental conditions for the reviewed methods. Furthermore, future perspectives about the analytical methodologies that can be developed in the near future for determination of these drugs are suggested.

Sensitive Inexpensive HPLC Determination of Novel Anticancer Combination in Nanoparticles and Rat Plasma: Pharmacokinetic Application

Two high-performance liquid chromatography-diode array detection methods have been developed and validated for the simultaneous quantification of genistein (GNS) and all trans retinoic acid (ATRA) as a novel anticancer combination therapy in their co-formulated nanoparticles and in rat plasma. Separation was performed on C18 column (250 × 4.6 mm, 5 μm) using celecoxib as internal standard. A mobile phase containing acetonitrile and water adjusted to pH 3 using 1% trifluoroacetic acid was delivered in gradient elution modes with time programmed UV detection. For extraction of the drugs and the internal standard from rat plasma, liquid- liquid extraction was applied. The proposed methods were validated as per International Conference on Harmonisation (ICH) guidelines (in the range 0.1-10 μg/mL for analysis of GNS and ATRA in nanoparticles) or according to Food and Drug Administration (FDA) guidance on bioanalytical method validation (in the range 0.025-20 μg/mL for analysis of GNS and ATRA in rat plasma). Pharmacokinetic study in six rats was performed following intravenous (IV) administration of a single dose of 0.5 mg/Kg of GNS and ATRA. The drugs' concentrations were measured up to 24 hours, and different pharmacokinetic parameters were calculated. The obtained parameters were comparable with the reported values for IV administration of each drug alone in rats. This confirms the applicability of the proposed method in monitoring the levels of the two drugs in vivo following their coadministration and indicating that the two drugs could be coadministered as a promising novel combination therapy for the treatment of lung cancer without great alteration in their pharmacokinetic parameters compared with their individual IV administration.

Green Multiplex Chromatographic Determination of Nine Penicillin Antibiotics Residues in Industrial Air Dust and Wastewater Environmental Samples

Determination of penicillin residues in different industrial effluents including wastewater and air samples is important to prevent exposure to residual amounts of penicillin and the development of antibiotic resistance. A green high performance liquid chromatography (HPLC) method coupled with diode array detection has been developed and validated for multiplex determination of nine penicillin antibiotics in the industrial air dust and wastewater environmental samples of penicillin facility in addition to the monitoring of facility surface cleaning. Separation was performed on C18 column with gradient elution of methanol and phosphate buffer (pH 4) at a flow rate of 1.5 mL min-1 and ultra violet (UV) detection at 220 nm. Low limits of detection were achieved (0.1-0.3 μg mL-1) indicating good sensitivity of the proposed. The method was applied for ensuring the efficiency of cleaning validation after worst-case selection. Recovery studies of the studied penicillins from fortified stainless steel and polycarbonate surfaces and swabs were between 91.91 and 100.22% with relative standard deviation 0.11-1.79%. The presence of any of the studied penicillins in wastewater samples from penicillin plant drainage was checked. Also, total air dust concentration (mg m-3) and % of penicillin active material residues in air dust were calculated from the area of the exposed group in suspension, tablet and vial production lines. The proposed method can be recommended for routine analysis of air and wastewater environmental samples for the detection of penicillin antibiotics at low levels as well as monitoring of facility surface cleaning with high accuracy and precision.

Multiple green spectroscopic methods for erdosteine determination in bulk and dosage form with extensive greenness evaluation

Four simple, sensitive, economical, and eco-friendly spectrophotometric and spectrofluorimetric methods for the assay of erdosteine (ERD) in bulk and dosage form have been developed and validated as per the current ICH guidelines. Method I involved the addition of the powerful oxidizing agent, potassium permanganate to ERD and measuring the oxidation product at 600 nm. Another oxidizing agent; ceric ammonium sulfate was used in Method II where ERD is oxidized resulting in a decline in the absorbance intensity of cerium (IV) ions, measured at 320 nm. Similarly, Method III employed the use of ceric ammonium sulfate, However, the fluorescence intensity of the resulting cerium (III) ions was recorded at λex/λem 255/355 nm, respectively. Whereas in Method IV, ERD was added to acriflavine leading to a proportional decrease in its native fluorescence. Various reaction conditions affecting the intensity of measurement were attentively investigated, optimized, and validated. All the suggested methods did not require any tedious extraction procedures nor organic solvents. The implementation of the proposed methods in ERD assay resulted in linear relationships between the measured signals and the corresponding concentrations of ERD in the range of 1-6, 0.1-1.0, 0.01-0.1, and 10-100 μg/mL with LOD values 0.179, 0.024, 0.0027 and, 3.2 μg/mL for methods I, II, III and IV respectively. The suggested methods were successfully applied to ERD analysis in pure form and in commercial capsules. Furthermore, the eco-friendliness of the proposed methods was thoroughly checked using various greenness testing tools. Lastly, this work, not only presents highly sensitive, green, mix-and-read methods for ERD determination, but also, describes the determination of ERD spectrofluorimetrically for the first time in the literature.

Simultaneous determination of lesinurad and co-administered drugs used in management of gout comorbidities to uncover potential pharmacokinetic interaction in rat plasma

Gout is one of the most prevalent forms of arthritis that is usually accompanied by other comorbidities. For this reason, multiple drugs are routinely prescribed for gout patients, which may affect the clinical course outcomes, and increase the risk of drug-drug interactions. This work presents a novel, simple, and sensitive high performance liquid chromatography (HPLC) method for the simultaneous determination of lesinurad (LES) and other co-administered drugs that are subject to potential pharmacokinetic interactions such as etoricoxib (ETC), eplerenone (EPL), and amiodarone (AMD) in rat plasma. Moreover, a pharmacokinetic study was conducted by co-administration of LES and ETC to rats to assess any possible alteration in their pharmacokinetic profiles and the obtained samples were analyzed using the developed method. Chromatographic separation was achieved using a gradient elution of a mobile phase consisting of acetonitrile and potassium dihydrogen orthophosphate buffer, pH 4.2 on a Zorbax Eclipse Plus C18 (4.6 × 250 mm, 5 μm particle size) column. The developed method exhibits adequate sensitivity with a LLOQ of 100 ng/mL and was successfully validated as per the FDA bioanalytical guidelines and was found to be linear over the range from 100 to 50,000 ng/mL for all the selected drugs. The results of the pharmacokinetic study showed an increase in the area under the curve (AUC) of each of the two drugs (LES and ETC) following the repeated administration of the other. This raises concerns of the possible renal injurious effect of ETC when co-prescribed with LES. Moreover, this work uncovers the necessity for therapeutic dose adjustment or increased clinical vigilance for side effects and/or lack of efficacy upon concomitant administration of the selected drugs to gout patients.