An efficient spectrofluorimetric method adopts doxazosin, terazosin and alfuzosin coupling with orthophthalaldehyde: Application in human plasma

An integrative analytical approach designed for feasible tranexamic acid assay using o-phthalaldehyde as a fluorogenic probe: applications to tablets, ampoules, and urine

Antifibrinolytic tranexamic acid (TRX) suppresses plasminogen activation to plasmin in a competitive way. TRX is approved for the management of heavy menstrual periods, hereditary angioedema, hemophilia, postpartum hemorrhage, surgery, tooth extraction, and severe blood loss after acute trauma. Here, the practical use of an isoindole derivative was established for a novel, easy-to-use, and affordable TRX assay. In the presence of a molecule containing a sulfhydryl group (2-mercaptoethanol) 0.02% v/v, the primary amine moiety in TRX allows its combination with o-phthalaldehyde to produce a luminous product. Excitation (338.8 nm) and emission (433.9 nm) wavelengths were used to monitor the isoindole fluorophore yield, and each operational variable was carefully examined and adjusted. The calibration graph was constructed with fluorescence intensity versus TRX concentration, excellent linearity was observed at concentrations between 40 and 950 ng/ml, and limit of detection and limit of quantitation were 41.3 and 13.6 ng/ml, respectively. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines were used to validate the method. The developed method for TRX assay in various dosage forms and urine was successfully implemented and was shown to be an effective, simple, and quick replacement for the TRX assay in clinical trials and quality control.

A novel and unusual utility of the cardiosintol drug as a fluoro-prober in the amendment of a highly fluorescent module for determining the non-fluorescent N-acetylcysteine drug

It is common to use reagents to determine the drugs by exploiting the properties of these reagents in the development of fluorescence of the target drug or sometimes increasing its intensity; this is the usual and predominant in the methods used in various techniques. But using a drug as a reagent to analyze another drug is unique, unusual, and uncommon; that's the idea of this paper. This is possible by creating a chemical modulation in the drug's structure using another drug. Targeted analyte molecules (N-acetylcysteine, as an example) that lack fluorogenic or chromophoric moieties cannot be monitored or evaluated without undergoing structural modification. Thus, the chemical mending of the analyte's molecular structure can achieve the transformational process. This protocoled analytical method generates an amended fluorescence sensation that can be chased fluorimetrically at 441 nm (emission) following excitation at 339 nm. When o-dialdehyde, diformylbenzene, a non-fluorescent moiety, is added to a solution of non-fluorescent analyte in the presence of cardiosintol drug, at a specific pH, the target drug-thiol moiety can be amended into a highly fluorescent compound. This study presented a sensitive and feasible fluorometric test for acetylcysteine. The response is linear throughout the range of 0.05-0.80 µg mL^-1. Quantum yield and procedure validation were evaluated according to I.C.H. standards. The formed mutated product was successfully applied to the precise assessment of the studied drug in batch powder and dose form(s), with no impact from excipients. Compared to the referenced publication, the outcomes demonstrate remarkable precision and accuracy.

Application of isoindole fluorophore formation for determination of linagliptin in the sole and co-formulated tablets: Application for plasma assay and content uniformity testing

Linagliptin is a new medicament belonging to dipeptidyl peptidase-4 enzyme inhibitors group. The mentioned medication is used to cure type 2 diabetes and is taken orally as a monotherapy or in a co-formulation with metformin. or empagliflozin. Herein, a novel, straightforward, and cost-effective method for linagliptin assay was developed with a workable use of an isoindole derivative. The primary amine moiety present in linagliptin enables its condensation with o-phthalaldehyde to form a fluorescent product in the presence of a sulfhydryl group-containing compound (2-mercaptoethanol) 0.01 % V/V. The isoindole fluorophore yield was monitored at (λ_excitation 337.8 nm, λ_emission 434.3 nm) and all experimental variables were meticulously checked and adjusted. Fluorescence intensity versus linagliptin concentration was plotted to construct the calibration graph, and excellent linearity was achieved at values between 50 and 2000 ng/mL. The validity of the method was verified through a rigorous examination of the ICH guidelines. The method application was successful for linagliptin in different dosage forms, content uniformity study, and monitoring in spiked plasma. The devised technique was demonstrated to be a promising, easy, and quick alternate method for linagliptin assayin clinical study and quality control.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

A synchronous spectrofluorometric technique for simultaneous detection of alfuzosin and tadalafil: applied to tablets and spiked biological samples

A facile, accurate, eco-friendly and sensitive spectrofluorometric method was evolved to assay alfuzosin hydrochloride (AFH) and tadalafil (TDF) in different matrices. Such a co-administered combination is clinically used for the treatment of lower urinary tract symptoms. Both compounds are characterized by their native fluorescence spectra upon excitation at specific wavelengths. Their characteristic fluorescence spectra were used for sensitive assay of the studied analytes in tablets and human biological samples. The assay principle is based on first-order synchronous spectrofluorometric scan using Δλ = 60 nm in which AFH peaks were recorded at 366 nm. Meanwhile, TDF measurements were recorded at 293 nm in the same scans without overlap with AFH spectra. Recent analytical chemistry trends were implemented to lessen occupational and environmental perils, using ethanol as a diluting solvent for method optimization and application. Linearity ranges were 5.0-90.0 and 10.0-100.0 ng ml^-1 for AFH and TDF, respectively in their raw materials with average % recoveries of 100.44% and 99.73% in raw materials, 100.15% and 100.20% in spiked plasma, and 97.14% and 99.99% in spiked urine. The proposed method was successfully applied to Prostetrol and Starkoprex commercial tablets with no interference with common tablet additives.

Green innovative fluorescence approach for the feasible and reliable assay of thiol-containing drugs; captopril as a model

In the present study, a novel spectrofluorimetric approach was designed for the analysis of captopril as a thiol-containing compound. The approach is based on the formation of a ternary fluorescent compound between the target thiol compound, ortho-phthaldehyde, and a suitable primary amine-containing compound. The produced 1-thio-alkyl-isoindole derivative exhibited very high emission activity in a faintly alkaline aqueous solution that could be monitored at 448 nm (excitation at 334 nm). 2-Amino-6-methyl-6-hydroxy-heptane was selected as the primary amine candidate that gave the high fluorescence intensity with the stability of the formed product. At the optimal experimental condition, the intensity of fluorescence of the formed product was linearly related to the concentration of captopril in 20-450 ng mL^-1 range. Commercial pharmaceutical tablets were analyzed, and the obtained results agreed with those of the published method regarding precision and accuracy. The mechanism of the reaction was discussed. In addition, the greenness of the approach was rated following eco-scale criteria.

Utilization of a micellar matrix for simultaneous spectrofluorimetric estimation of alfuzosin hydrochloride and vardenafil hydrochloride

A sensitive and direct spectrofluorimetric method was developed for simultaneous quantitation of two co-administered drugs, namely, alfuzosin hydrochloride (AFH) and vardenafil hydrochloride (VRH). Both drugs exhibited native fluorescence properties that could be exploited to assay them in biological fluids with high sensitivity. Spectrofluorimetric analysis of AFH and VRH is based on excitation of both drugs at 265 nm where emission spectra were recorded separately for AFH and VRH at 380 and 485 nm, respectively. Micellar trends in analytical chemistry were adopted to minimize both environmental and occupational hazards, using distilled water and sodium dodecyl sulphate (serves as a micellar medium that enhanced the sensitivity of AFH and VRH) for analysis of both drugs in their raw materials, tablets, and human biological fluids (plasma and urine). Linearity ranges were 1.0-16.0 and 10.0-700.0 ng mL^-1 for AFH and VRH, respectively. The proposed method was successfully assessed for analysis of AFH and VRH in spiked human plasma and urine samples over the following concentrations: 1.0-12.0 ng mL^-1 and 4.0-400.0 ng mL^-1 for both drugs, simultaneously with mean recoveries of 101.08 % and 102.06 % in plasma and 96.75 % and 92.8 % in urine. Statistical analysis of the practical results has proved quite good agreement and revealed there were no significant differences in the accuracy and precision with those obtained by the comparison methods. The proposed method was applied successfully to Prostetrol® and Powerecta® commercial tablets without interference with tablet additives.

Orthophthaldehyde as a fluorescent probe for the feasible and sensitive assay of heptaminol: application to dosage forms and real human plasma

The antihypotensive drug heptaminol was determined using a spectrofluorimetric method and ortho-phthaladehyde as a fluorescence probe. The drug was mixed with the reagent in the presence of 2-mercaptoethanol and the reaction was carried out in slightly alkaline aqueous solution containing 0.1 M sodium hydroxide. The resulting product exhibited high fluorescence activity that was measured at 451 nm after excitation at 334 nm. The linearity range of the method was 5-100 ng ml^-1 with a lower detection limit of 1.8 ng ml^-1 . The procedure was evaluated according to the International Council of Harmonization guidelines. The proposed method was applied to analyze the drug in pharmaceutical tablets and oral drops. In addition, the present study represents the first spectrofluorimetric method for the determination of the cited drug in real human plasma. The method provided high recovery percentages without any interference from coexisting pharmaceutical excipients or the components of human plasma.

Micellar sensitized Resonance Rayleigh Scattering and spectrofluorometric methods based on isoindole formation for determination of Eflornithine in cream and biological samples

α-Difluoromethylornithine or Eflornithine is an FDA-approved drug used for the treatment of Sleeping Sickness (as vials dosage form) and also used for diminishing the unwanted excess facial hair in the hirsutism (as creams dosage form). The proposed work is based on the condensation interaction between the amino moiety of Eflornithine and O-phthalaldehyde/2-mercaptoethanol to form a highly fluorescent isoindole derivative. The fluorescence and the Resonance Rayleigh Scattering (RRS) intensities of the reaction product were greatly augmented upon the addition of hexadecyl-trimethyl ammonium bromide by 153% and 250%, respectively. After optimization of the reaction conditions, the formed isoindole derivative was measured fluorometrically at λ_emission= 429 nm after λ_excitation= 337 nm. Moreover, the significant augmentation in the RRS intensity of the formed product was measured at λ_max= 422 nm. In regards to accuracy, sensitivity, robustness and precision, the proposed methods were validated according to ICH guidelines. Furthermore, the proposed methods were successfully applied for the assay of Eflornithine in various commercial brands of the pharmaceutical cream samples with good recovery. In addition to the current fluorometric method was confirmed to be effective in the assaying of Eflornithine in spiked plasma and urine specimens with good recovery.

Eco-friendly Spectrophotometric Methods for Assessment of Alfuzosin and Solifenacin in their new Pharmaceutical Formulation; Green Profile Evaluation via Eco-scale and GAPI Tools

Background:

Alfuzosin is recently co-formulated with solifenacin for relieving two coincident urological diseases, namely; benign prostate hyperplasia and overactive bladder.

Objective:

Herein, green, simple and rapid spectrophotometric methods were firstly developed for simultaneous determination of the two cited drugs in their co-formulated pharmaceutical capsule

Methods:

Alfuzosin, which is the major component in the dosage form, was directly assayed at its extended wavelength at 330.0 nm. The challenging spectrum of the minor component, solifenacin, was resolved by five spectrophotometric methods, namely; Dual Wavelength (DW) at 210.0 & 230.0 nm, first derivative (1D) at 222.0 nm, Ratio Difference (RD) at 217.0 - 271.0 nm, derivative ratio (1DD) at 223.0 and mean centering of ratio spectra (MC) at 217.0 nm.

Results:

The proposed methods were successfully validated as per ICH guidelines. Alfuzosin showed linearity over the range of 4.0 - 70.0 μg/mL, while that of solifenacin were 4.0 - 50.0 μg/mL for DW, 2.0 - 70.0 μg/mL for 1D and RD methods, 1.0 - 70.0 μg/mL for 1DD and 4.0 - 70.0 μg/mL for MC method. Statistical comparison with their official ones showed no noticeable differences. The methods showed good applicability for assaying drugs in their newly combination. Besides the eco-scale, the greenness profile of the methods was assessed and compared with the reported spectrophotometric one via the newest metric tool; Green Analytical Procedure Index (GAPI).

Conclusions:

The proposed methods are superior in not only being smart, accurate, selective, robust and time-saving, but also in using distilled water as an eco-friendly and cheap solvent.

Simple and fast LC-MS/MS method for quantification of terazosin in human plasma and application to bioequivalence study

A simple, fast and sensitive LC-MS/MS method was developed to quantify terazosin in human plasma. The mobile phase consisted of acetonitrile-0.1% (v/v) formic acid (70:30, v/v). Prazosin was used as internal standard (IS). As deproteinization agent, acetonitrile produced a clean sample. A higher response intensity with more symmetrical peak was obtained using Agilent Poroshell 120 EC-C18 - Fast LC column (100 × 2.1mmID, 2.7 μm) compared with Kinetex XB-C18 (100 × 2.1 mm, 2.6 µm) column. The response of terazosin and IS were approximately two times in citrate phosphate dextrose (CPD) plasma compared with dipotassium ethylenediaminetetraacetic acid (K₂EDTA) plasma. Plasma calibration curve was linear from 1.0 to 100.0 ng/mL, with coefficient of determination r² ≥ 0.99. The within-run and between-run precision values (CV, %) were <5.2% and <7.8%, while accuracy values were 102.8-112.7% and 103.4-112.2%. The extended run accuracy was 98.6-102.8% and precision (CV, %) 4.3-10.4%. The recovery of analyte was >98% and IS >94%. Terazosin in plasma kept at benchtop was stable for 24 h, in autosampler tray for 48 h, in instrumentation room for 48 h, for 7 freeze-thaw cycles and in freezer for 140 days. Terazosin and IS stock standard solutions were stable for 140 days at room temperature and in the chiller. The high throughput method was successfully utilized to measure 935 samples in a bioequivalence study of terazosin.

A new approach based on isoindole formation reaction for sensitive fluorimetric assay of milnacipran in tablets and biological fluids (plasma/urine)

The current study describes a new, sensitive, and economic protocol for milnacipran analysis. Milnacipran was introduced as a therapy for fibromyalgia and depression. It acts by unique and equal inhibition of noradrenaline and serotonin neurotransmitters reuptake. In the presence of 2-mercaptoethanol, the amino moiety of milnacipran condenses with o-phthalaldehyde to generate isoindole fluorescent derivative. The isoindole product was measured at (λ ex 338.5 nm, λ em 433.5 nm) and condensation variables were strictly optimized. The fluorescence intensity of measurements was plotted versus milnacipran concentration to give a linearity range over 200-4000 ng mL-1. The proposed approach was fully validated by the directives of ICH guidelines and applied without any influence of combined excipient for milnacipran tablet analysis. Furthermore, the procedure was applied in spiked urine and plasma analysis with excellent percentage recovery.

Mending the fluorescence of two α-blockers through a semiquinoid formation: Hyphenated with experimental design optimization

Herein, a selective and rapid spectrofluorimetric method coupled with experimental design approach for reliable and efficient determination of two α-blockers, namely: terazosin hydrochloride (TER) and doxazosin mesylate (DOX) in their marketed tablets was developed. The presented method adopts formation of a semi-quinoid form of the studied drugs in borate buffer. The effects of parameters influencing fluorescence intensity including pH, the volume of buffer and diluting solvent were optimized using an experimental design methodology. The optimum conditions were found to be pH: 9.8, the volume of buffer: 2.0 mL and diluting solvent: water. Under the optimum experimental conditions, a large enhancement of the studied drugs fluorescence was obtained, measured at 387 after excitation at 246 nm for either TER or DOX with limits of detection 0.05 and 0.14 ng mL^-1 and limits of quantification 0.14 and 0.43 ng mL^-1 in the concentration ranges of 0.2-30.0 ng mL^-1 and 0.5-30.0 ng mL^-1 for TER and DOX, respectively. The presented method was validated according to the ICH guidelines. Furthermore, it extended to perform the content uniformity testing and analysis of the studied drugs in spiked human plasma with % recovery (96.00 ± 0.45-101.42 ± 1.20%, n = 3).

A novel HPLC-DAD method for simultaneous determination of alfuzosin and solifenacin along with their official impurities induced via a stress stability study; investigation of their degradation kinetics

Stability and impurity profiling are in high demand to guarantee the potency, safety and efficacy of new formulations along with their shelf-life. In this study, stability testing of alfuzosin (ALF) and solifenacin (SOL) in their newly co-formulated capsules was conducted under different stress conditions. The obtained degradation products were structurally elucidated and found to be their official impurities, namely; ALF impurity-D and SOL impurities-A, E & I. A selective and reliable stability-indicating HPLC method was developed for assaying the cited drugs along with three of those official impurities. Chromatographic separation was accomplished within 8 minutes using a XBridge® C18 column as the stationary phase and acetonitrile : phosphate buffer (pH 8) : triethylamine (60 : 40 : 0.02, by volume) as the mobile phase at a flow rate of 1.3 mL min-1. Quantification of the analytes was performed at 210 nm using a diode array detector through which peak purity was assessed. The proposed method was validated as per ICH guidelines and it was successfully applied for the determination of the cited drugs in their combined pharmaceutical formulation with percent recoveries of 100.47 and 100.15 for ALF and SOL, respectively. Moreover, the proposed method was exploited for the assessment of the two drugs' stability in Solitral® capsules under accelerated storage conditions. The method was further extended for studying the degradation kinetics of the two drugs.

Automated fluorimetric sensor for glutathione based on zone fluidics

A zone-fluidics (ZF) based automated fluorimetric sensor for the determination of glutathione (GSH) is reported. Discrete zones of GSH and o-phthalaldehyde (OPA) mix and react on-line under mild basic pH without the need of additional nucleophillic reagents, to yield a fluorescent isoindole derivative (λ_ex/λ_em = 340/425 nm). The proposed ZF sensor was optimized (pH, c(OPA), time, instrumental variables) and validated. Cysteine, glutamate, glycine and ammonium were representatively examined in terms of selectivity and were found not to react in 10-fold excess. Linearity was proved in the range of 5-100 μmol L^-1 GSH, with an LOD of 1 μmol L^-1 at a practical sampling rate of 20 h^-1 and RSD < 0.5% (within-day) and 4.2% (day-to-day). The dosage uniformity of commercially available GSH - containing nutraceuticals was evaluated.

Validated RP-HPLC method for quantification of doxazosin in human plasma: Application in a bioequivalence study

OBJECTIVES

The aim of the present study was to validate a simple, sensitive, HPLC method of analysis of doxazosin in human plasma with fluorescence detection.

METHODS

The validated method employed one-step direct protein precipitation with acetonitrile. Chromatographic separation was attained using a reverse-phase 250mm×4.6mm 5μ Hypersil® BDS C 18 column and the mobile phase consisted of 10mm sodium dihydrogen phosphate dihydrate (pH=3.0) and acetonitrile at a ratio of (65:35 v/v). The method was evaluated in terms of linearity, precision, accuracy, selectivity and stability as per standard guidelines. The total run time was about 4.5min which make this method suitable for high throughput analyses. This method was applied to the bioequivalence study of two doxazosin tablets in healthy human volunteers.

RESULTS

Good linear response was achieved over the range of 5.0-200ng/mL. The observed within- and between-day assay precision ranged from 0.64% to 14.73%; accuracy varied between 94.11% and 105%. The 90% confidence intervals for the ratio Cmax, and AUC 0-∞ of the test product over those of reference were within the acceptable range (0.8-1.25) for bioequivalence.

CONCLUSION

The developed method was simple and could be applied to therapeutic drug monitoring of doxazosin.

Studies on the Kinetics of Doxazosin Degradation in Simulated Environmental Conditions and Selected Advanced Oxidation Processes

The photochemical behavior of doxazosin (DOX) in simulated environmental conditions using natural waters taken from local rivers as a solvent was studied. The chemical characteristics of applied waters was done and a correlation analysis was used to explain the impact of individual parameters of matrix on the rate of the DOX degradation. It was stated that DOX is a photoliable compound in an aqueous environment. Its degradation is promoted by basic medium, presence of environmentally important ions such as Cl−, NO3−, SO42− and organic matter. The kinetics of DOX reactions with OH− and SO4− radicals were examined individually. The UV/H2O2, classical Fenton and photo-Fenton processes, were applied for the generation of hydroxyl radicals while the UV/VIS:Fe2(SO4)3:Na2SO2 system was employed for production of SO4− radicals. The obtained results pointed that photo-Fenton, as well as UV/VIS:Fe2(SO4)3:Na2SO2, are very reactive in ratio to DOX, leading to its complete degradation in a short time. A quantitative density functional theory (DFT) mechanistic study was carried out in order to explain the molecular mechanism of DOX degradation using the GAUSSIAN 09 program.