A sustainable sensitive spectrofluorimetric approach for the determination of the multipotent protein lactoferrin in different pharmaceuticals and infant milk formula: Compliance with greenness metrics

The current study presents the first spectrofluorimetric approach for the estimation of lactoferrin, depending on the measurement of its native fluorescence at 337 nm after excitation at 230 nm, without the need for any hazardous chemicals or reagents. It was found that the fluorescence intensity versus concentration calibration plot was linear over the concentration range of 0.1-10.0 μg/mL with quantitation and detection limits of 0.082 and 0.027 μg/mL, respectively. The method was accordingly validated according to the ICH recommendations. The developed method was applied for the estimation of lactoferrin in different dosage forms, including capsules and sachets with high percent recoveries (97.84-102.53) and low %RSD values (<1.95). Lactoferrin is one of the key nutrients in milk powder and a significant nutritional fortifier. In order to assess the quality of milk powder, it is essential to rapidly and accurately quantify the lactoferrin content of the product. Therefore, the presented study was successfully applied for the selective estimation of lactoferrin in milk powder with acceptable percent recoveries (96.45-104.92) and %RSD values (≤3.607). Finally, the green profile of the method was estimated using two assessment tools: Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE), which demonstrated its excellent greenness.

Highly fluorescent nitrogen-doped carbon quantum dots prepared using sucrose and urea: Green synthesis, characterization, and use for determination of torsemide in its tablets and plasma samples

A simple and facile microwave-assisted method was developed for the synthesis of highly fluorescent nitrogen-doped carbon quantum dots (N-CQDs) using sucrose and urea. The produced quantum dots exhibited a strong emission band at 376 nm after excitation at 216 nm with quantum yield of 0.57. The as-prepared N-CQDs were characterized using Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) images, and ultraviolet-visible (UV-visible) spectra. The average particle size was 7.7 nm. It was found that torsemide (TRS) caused an obvious quenching of the fluorescent N-CQDs; so, they were used for its spectrofluorometric estimation. An excellent linear correlation was found between the fluorescence quenching of N-CQDs and the concentration of the drug in the range of 0.10 to 1.0 μg/mL with limit of quantitation (LOQ) of 0.08 μg/mL and limit of detection (LOD) of 0.027 μg/mL. The method was successfully applied for the assay of the drug in its commercial tablets and spiked human plasma samples, and the results obtained were satisfactory. Complex GAPI was used for greenness assessment of the analytical procedures and the pre-analysis steps. Interference likely to be introduced from co-administered drugs was also studied.

Estimation of Two Diuretics Using Fluorescent Nitrogen Doped Carbon Quantum Dots: Application to Spiked Human Plasma and Tablets

Highly fluorescent nitrogen doped carbon quantum dots (N-CQDs) were prepared by a single-step method based on microwave heating of cane sugar and urea. The produced N-CQDs were applied as nano-sensors for the spectrofluorimetric determination of eplerenone and spironolactone. A strong emission band at 376 nm was obtained after excitation at 216 nm due to the produced N-CQDs. The native fluorescence of N-CQDs was obviously quenched upon adding increased concentrations of each drug. A strong correlation was found between the fluorescence quenching of N-CQDs and the concentration of each drug. The method was found to be linear over the range of 0.5 to 5.0 μg/mL for eplerenone and 0.5 to 6.0 μg/mL for spironolactone with LOQ of 0.383 μg/mL and 0.262 μg/mL. The developed method was further extended for determination of both drugs in their pharmaceutical tablets and spiked human plasma. The results obtained were statistically compared with those of reported methods. The mechanism of fluorescence quenching of N-CQDs by the two drugs was discussed.

Spectrofluorometric determination of cinacalcet hydrochloride: greenness assessment and application to biological fluids andin-vitrodissolution testing

A facile, simple, green and sensitive spectrofluorometric method was developed for determination of the calcimimetic drug cinacalcet hydrochloride. It is used for the treatment of hyperparathyroidism. The drug showed high native fluorescence intensity at 320 nm after excitation at 280 nm. The method was linear over the range of 5.0-400.0 ng ml^-1with excellent correlation (R²= 0.9999). Limit of detection (LOD) and limit of quantitation (LOQ) values were 1.19 and 3.62 ng ml^-1, respectively. The percentage recovery was found to be 100.42% ± 1.39 (n=8). The proposed method was successfully applied for determination of cinacalcet in spiked human plasma samples with % recoveries of (87.23 to 109.69%). Two recent greenness metrics (GAPI and Analytical Eco-Scale) were chosen to prove the eco-friendly nature of the method. Furthermore, the proposed method was successfully applied to dissolution study of commercial cinacalcet tablets. The interference likely to be introduced by some commonly co-administrated drugs such as metoprolol and itraconazole was studied; the tolerance limits were calculated.

Use of green fluorescent nano-sensors for the determination of furosemide in biological samples and pharmaceutical preparations

BACKGROUND

Carbon quantum dots (CQDs) are new class of carbon nanoparticles. Recently, they have been widely used as fluorescent probes due to their easy accessibility, optical properties and chemical inertness. Many available precursors are used in the synthesis of carbon quantum dots. The electrical and optical properties of CQDs could be enhanced by doping hetero atoms such as nitrogen or sulfur into their structure.

OBJECTIVE

The current work presents the synthesis and characterization of water-soluble nitrogen doped carbon quantum dots (N-CQDs) and their use as fluorescent nano-sensors for the spectrofluorimetric determination of furosemide in its pharmaceutical preparations and spiked human plasma.

METHODS

A domestic microwave was used to prepare the N-CQDs by heating a solution of sucrose and urea till complete charring (about ten minutes). The produced N-CQDs exhibit a strong emission band at 376 nm after excitation at 216 nm. Furosemide caused a quantitative quenching in the fluorescence intensity of the produced N-CQDs.

RESULTS

The proposed method was validated according to ICH Guidelines. The method was found to be linear over the range of 0.1-1.0 µg/mL with LOQ of 0.087 µg/ml.

CONCLUSION

Ecofriendly nano fluorescent sensors (N-CQDs) were successfully synthesized. The size of N-CQDs was distributed in the range of 6.63 nm to 10.23 nm with an average of 8.2 nm. The produced N-CQDs were used as fluorescent probes for the estimation of furosemide in its pharmaceutical preparations as well as spiked human plasma samples.

Utility of a xanthene-based dye for determination of nilotinib using two spectroscopic approaches. Applications to bulk powder, capsules, and spiked human plasma

Novel, selective, facile, and precise spectroscopic approaches were validated to determine nilotinib hydrochloride, a tyrosine kinase inhibitor used to treat patients with chronic myeloid leukemia. These approaches depend on the reaction of the tertiary amine group of nilotinib with erythrosine B in the Britton-Robinson buffer at pH 4. Method I, depends on measuring the absorbance of the formed complex at 551 nm. The absorbance concentration plot showed linearity over the concentration range of 1.0 to 9.0 μg/ml. Method II, involved the measurement of the quenching of the native fluorescence of erythrosine B by adding nilotinib in an acidic medium. The fluorescence quenching of erythrosine B was measured at 549 nm after excitation at 528 nm. This approach showed excellent linearity in the concentration range of 0.04 to 0.7 μg/ml. The limit of detection values for Method I and Method II were 0.225 and 0.008 μg/ml, respectively, while the limit of quantitation values for Method I and Method II were 0.68 and 0.026 μg/ml, respectively. To get the optimal conditions, factors that may affect the formation of the ion-pairing complex were thoroughly examined. The two approaches were carefully validated following the International Conference of Harmonization (ICH Q2R1) guidelines. Statistical assessment of the results achieved using the suggested and previously published comparison approaches showed no significant difference. The approaches were successful in determining nilotinib in a pharmaceutical dosage form as well as spiked human plasma samples. The eco-friendly properties of the methods were evaluated by three different tools.

Investigation of facile spectroscopic approaches for rapid calycosin determination in invitro biological samples and pharmaceuticals; application to the content uniformity of capsules

Calycosin, the major bioactive isoflavonoid inAstragali Radix and an important anti-viral drug with a variety of pharmacological actions, is being determined by five different spectroscopic methods. Two spectrophotometric methods have been investigated including measuring the absorption spectra at λ^max = 270 nm and the first derivative spectra at λ = 288 nm for methods I and II, respectively. For the first time; the native fluorescence of calycosin is measured without adding any reagents. The fluorescence intensity was measured at 340 nm after excitation at 282 nm in method III. The fourth method involves the direct measuring of a first derivative spectrofluorimetric emission peak at 292 nm. In method V synchronous fluorescence spectra were recorded in methanol at Δλ = 70 nm. The linear range for the fluorescence-based methods was 0.05-1.0 µg/mL and for the UV-based methods was 0.5-10.0 µg/mL. The methods were validated per International Council of Harmonization (ICHQ2R1) guidelines. The limits of detection were found to be down to 0.11 and 0.12 µg/mL for the spectrophotometric methods, and 15.0, 18.0,16.0 ng/ mL, for the spectrofluorimetric approaches respectively, representing the high sensitivity. Accordingly, this permitted the quantitation of calycosin in spiked human plasma samples with satisfactory percentage recoveries (94.50.-102.50 %). The methods were utilized for calycosin analysis in different matrices including plasma and capsules with high precision and accuracy.

Utility of Kolliphor RH 40 in micellar sensitized fluorescence of the novel tyrosine kinase inhibitor "Erdafitinib": Application to human plasma

Erdafitinib is the first treatment targeting susceptible fibroblast growth factor receptor (FGFR) genetic alterations in patients with locally advanced or metastatic urothelial carcinoma. A simple and precise spectrofluorimetric method was developed for its determination depending on fluorescence enhancement using Kolliphor RH 40 micellar medium at pH 10. The fluorescence intensity was measured at 495 nm after excitation at 410 nm. Different experimental parameters affecting the fluorescence intensity, including type of organized medium, diluting solvent, buffer type and pH were studied during optimization phase. Validation according to ICH Q2(R1) guidance was fully fulfilled. The method was linear over the range of 50 - 800 ng/mL. The lower limit of detection (LOD) and lower limit of quantitation (LOQ) were 14.36 and 43.50 ng/mL, respectively. The relative standard deviation values of intraday and interday precisions were less than 1.93 %. The proposed method was successfully applied to laboratory-prepared tablets. Furthermore, the high sensitivity of the method allowed its application on spiked human plasma samples with a high percent of recovery. The greenness of the method was investigated as an Eco-friendly alternative for erdafitinib determination with minimal organic solvent consumption.

Utility of a novel turn-off fluorescence probe for the determination of tranilast, an adjunctive drug for patients with severe COVID-19

Tranilast (TR) could be investigated as a suitable anti-inflammatory and NLRP3 inflammasome inhibitor medication for the treatment of COVID-19 acute patients. Owing to its importance, our study was constructed for the determination of TR using a new, fast, sensitive, and reliable green spectrofluorimetric method. TR was quantified in this study by forming a complex with the acriflavine (AC) reagent. The reaction between TR and AC quenched the fluorescence of AC through the formation of an ion-association complex and the response was measured at 493 nm after excitation at 263 nm. It was observed that the quenching of the fluorescence of AC was linear (r = 0.9998) with the concentration of TR in the range of 1.0–15.0 μg mL⁻¹. The limit of detection was 0.224 μg mL⁻¹, and the limit of quantification was 0.679 μg mL⁻¹. The fluorescence quenching mechanism was carefully studied and was confirmed to be able to analyze TR in its pure form and its prepared pharmaceutical dosage form. To validate the method, the international conference of harmonization (ICH) Q₂R₁ guidelines were followed. The statistical assessment of the proposed and comparison methods revealed no significant differences between them. Moreover, the green criteria of the method were evaluated and confirmed.

Tranilast (TR) could be investigated as an anti-inflammatory and NLRP3 inflammasome inhibitor medication using acriflavine.

Two Spectroscopic Methods for Estimation of Anti-migraine Medications; Sumatriptan and Zolmitriptan Based on Nucleophilic Substitution Reaction

Sensitive and selective spectrophotometric and spectrofluorimetric methods have been developed for estimation of two antimigraine drugs namely sumatriptan succinate and zolmitriptan. These methods depend on producing a yellow-colored product after the reaction of the two drugs with 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl). The reaction products exhibit maximum absorbance at 481 nm in borate buffer of pH 9 and fluorescence emission peak at 540 nm after excitation at 470 nm for the two drugs. The linear ranges were 5-60 μg/mL for SUM and 5-50 μg/mL for ZOL in the spectrophotometric method (method I), while 0.4-4 μg/mL for SUM and 0.5-5 μg/mL for ZOL in the spectrofluorimetric method (method II). The methods validity was assessed according to ICH guidelines. Statistical analysis of the results obtained from the proposed and comparison methods confirmed that the proposed methods are highly accurate and precise. The suggested methods could be used for the determination of the mentioned drugs in both pure and tablets.

LC-MS/MS monitoring of the colorectal carcinoma cellular uptake and entrapment of sorafenib and its N-oxide active metabolite

Sorafenib (SOR) is a multikinase inhibitor with a mild activity against colorectal cancer cells due to multi-drug resistance mechanisms. Potentiated SOR activity was expected upon combination with some ginger derived compounds due to their interference with intracellular drug metabolism. Studying such combination necessitates the development of a sensitive validated LC-MS/MS method for the determination of intra and extracellular concentration of SOR and its N-oxide metabolite (SNX) in colorectal cancer cells. SOR, SNX and the internal standard (diclofenac sodium) were efficiently separated on Eclipse plus C18 column (3.0 ×150 mm, 5 µm) using isocratic elution with acetonitrile and 0.01 M ammonium formate aqueous solution containing 0.1% formic acid (69:31, v/v). Sample pretreatment using solid phase extraction was optimized and the mean percent recoveries were more than 97.01% for both analytes. Detection was conducted at positive ion multiple reaction monitoring (MRM) mode and the monitored mass transitions were 465.2 → 252.2 for SOR and 481.1 → 286.0 for SNX. The method was linear over the range 0.25 - 200.00 ng/mL (r² ≥ 0.9992) for SOR and 0.10 - 125.00 ng/mL (r² ≥ 0.9990) for SNX in both intra and extracellular matrices. The lower limits of quantification (LLOQ) were 0.25 and 0.10 ng/mL for SOR and SNX, respectively. Accuracies were within 94.25 - 109.45% and precision CV values did not exceed 7.63%. The method was able to monitor the cellular uptake and entrapment of both analytes and to prove the positive effect of the ginger derived compounds on SOR activity.

Concurrent estimation of some co-administered antimicrobial drugs applying conventional and first derivative synchronous fluorescence spectroscopy techniques

For the estimation of some co-administered antimicrobials, two highly accurate and precise spectrofluorimetric methods were developed. Fluconazole (FLZ) is co-administered with either ciprofloxacin (CPR) or ofloxacin (OFX) for the treatment of certain microbial infections. On the other hand, another antimicrobial drug, vancomycin (VNC) is co-administered with ciprofloxacin (CPR) for peritonitis treatment. In method I, conventional spectrofluorimetry has been introduced for the concurrent quantitative estimation of FLZ in presence of OFX or CPR. While in method II, a first derivative synchronous spectrofluorimetric technique was adapted for quantitation of VNC and CPR co-administered combination. Both of them were utilized for estimation of the considered drugs in raw materials, laboratory prepared mixtures, dosage forms, and biological fluids. Method I was relied on simultaneous measuring of the native fluorescence of FLZ and OFX or CPR without any overlapping between the emission spectra of each binary mixture (FLZ / OFX) and (FLZ / CPR). Fluorescence intensities were measured at 283.0, 483.0 and 436.0 nm after excitation at 262.0, 292.0 and 275.0 nm for FLZ, OFX and CPR, respectively. Method II was utilized the synchronous fluorescence intensity of VNC and CPR in methanol at Δλ = 40 nm. The first derivative synchronous spectra were calibrated at 297.0 nm for VNC and at 379.5 nm for CPR. Different variables influencing conventional and synchronous fluorescence intensities of the four antimicrobials under investigation were precisely optimized. Both methods were successfully investigated for the determination of the studied drugs in plasma. The linear data analysis for the calibration curves reveals a good relationship in the ranges of 1.0-10.0, 0.25-2.5 and 0.06-0.6 μg/mL for FLZ, OFX and CPR for method I with limits of detection 0.144, 0.038 and 0.007 μg/mL and limits of quantitation of 0.437, 0.114 and 0.021 μg/mL for FLZ, OFX and CPR, respectively. Linearity range for method II was 0.5 -10.0 μg/mL for VNC and CPR with detection limits of 0.127 and 0.110 μg/mL and quantitation limits of 0.380 and 0.334 μg/mL for VNC and CPR, respectively. International Council on Harmonization ICH Q2 (R1) Guidelines were followed in the developed methods validation. The achieved outcomes were statistically compared with those found by the reported ones, and no significant difference was observed.

Green and sensitive spectrofluorimetric method for the determination of two cephalosporins in dosage forms

Using two green and sensitive spectrofluorimetric methods, we quantified two cephalosporins, cefepime (CFM) and cefazolin (CFZ), in raw and pharmaceutical formulations. The first method is based on the reaction between CFM and fluorescamine (borate buffer, pH 8), which yields a highly fluorescent product. After excitation at 384 nm, the fluorescent product emits light at 484 nm. At concentration ranges from 12.0 to 120.0 ng ml^-1, the relative fluorescence intensity/concentration curve was linear with a limit of quantification (LOQ) of 2.46 ng ml^-1. The second method relied on measuring the CFZ quenching action on acriflavine fluorescence through formation of an ion-associate complex using Britton-Robinson buffer at pH 8. We measured acriflavine fluorescence at 505 nm after excitation at 265 nm. The decrease in acriflavine fluorescence intensity was CFZ concentration-dependent. Using this method, we quantified CFZ in concentrations ranging from 1 to 10 µg ml^-1 with a LOQ of 0.48 µg ml^-1. We studied and optimized the factors influencing reaction product formation. Moreover, we adapted our methods to the investigation of the mentioned drugs in raw and pharmaceutical formulations with greatly satisfying results. We statistically validated our methods according to International Council on Harmonisation Guidelines. The obtained results were consistent with those obtained with the official high-performance liquid chromatography methods.

Investigation of some univariate and multivariate spectrophotometric methods for concurrent estimation of Vancomycin and Ciprofloxacin in their laboratory prepared mixture and application to biological fluids

Four simple, rapid, accurate and precise spectrophotometric methods were established and validated in accordance with ICH Q2 (R1) guidelines for the simultaneous determination of Vancomycin (VNC) and Ciprofloxacin (CPR) in their raw materials, laboratory prepared mixtures and pharmaceutics. Method A depends on using first derivative spectrophotometry (D¹) where VNC and CPR were resolved at 243.6 and 262.0 nm, respectively. Concerning method B, it is based on utilizing first derivative of ratio spectra (DD¹) where determination was performed at the peak maxima at 244.0 nm and 258.0 nm for VNC and CPR, respectively. Two chemometric models were applied for the quantitative analysis of both drugs in their laboratory prepared mixtures, namely, partial least squares (PLS) (method C) and artificial neural network (ANN) (method D). For univariate methods linearity range for both drugs was in the range of 3-30 and 1-10 μg/mL for VNC and CPR, respectively. Multivariate calibration methods using five level, two factor calibration model for the development of 25 mixtures were also applied for the simultaneous estimation of the two drugs in their laboratory prepared mixture using spectral region from 200.0 to 300.0 nm using interval 1 nm. The suggested methods have been successfully extended to the assay of the two studied drugs in laboratory-prepared mixtures and pharmaceuticals with excellent recovery. First derivative spectrophotometry (D¹) was also applied for the assay of both analytes in spiked human plasma with good recovery. No interaction with common pharmaceutical additives has been observed which indicate the selectivity of the method. The results obtained were favourably compared with those obtained applying the reported methods. The methods are validated in compliance with the ICH Q2 (R1) guidelines and the measured accuracy and precision are assessed to be within the accepted limits.

Spectrofluorimetric investigation for determination of sumatriptan succinate: application to tablets and spiked human plasma

A simple and highly sensitive spectrofluorimetric method for the estimation of sumatriptan succinate has been investigated. The suggested method depends on the determination of the intrinsic fluorescence properties of the drug in aqueous systems at λ_em 350 nm following λ_ex at 225 nm. The linearity range was 10-100 ng/ml, with a detection limit and quantitation limit of 1.2 and 3.6 ng/ml, respectively. The suggested method was sufficiently successful for determination of sumatriptan its pharmaceutical tablets as well as in spiked human plasma. Moreover, the validation parameters were determined following International Council for Harmonisation guidelines. Statistical analysis of the obtained results from the proposed and reference methods showed no significance difference between the two methods regarding accuracy and precision.

Liquid Chromatographic Method for the Simultaneous Determination of Eprosartan and Hydrochlorothiazide in Tablets and Human Plasma

A new, specific, and sensitive RP-HPLC method was developed for the simultaneous determination of eprosartan (EPR) and hydrochlorothiazide (HCT). Good chromatographic separation was achieved using a 250 × 4.6 mm id, 5 μm particle size Symmetry® C18 column. The mobile phase acetonitrile–0.1 M phosphate buffer (35 + 65, v/v), pH 4.5, was pumped at a flow rate of 1 mL/min, with UV detection at 275 nm. The method showed good linearity in the ranges of 0.5–50 and 0.1–10 μg/mL, with LOD of 0.06 and 0.02 μg/mL and LOQ of 0.20 and 0.08 μg/mL for EPR and HCT, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixture and co-formulated tablets. The method was further extended to the in vitro and in vivo determination of the two drugs in spiked and real human plasma. Interference likely to be encountered from the co-administered drugs was studied.

Spectrofluorometric Determination of Olanzapine and Fluphenazine Hydrochloride in Pharmaceutical Preparations and Human Plasma Using Eosin: Application to Stability Studies

A simple, rapid, and sensitive spectrofluorometric method has been developed for the determination of olanzapine (OLZ) and fluphenazine hydrochloride (FPZ HCl). The proposed method is based on the quantitative quenching effect of the studied drugs on the native fluorescence of eosin at pH 3.4 and 3.2 for OLZ and FPZ HCl, respectively. The fluorescence was measured at 547 nm after excitation at 323 nm. The fluorescence-concentration plots were rectilinear over the range of 0.051.0 and 0.101.0 g/mL, with lower detection limits of 1.8 103 and 1.2 103 g/mL, for OLZ and FPZ HCl, respectively. The proposed method was successfully applied to the analysis of commercial tablets and ampules containing the drugs, and the results were in good agreement with those obtained with reference methods. The proposed method was further applied to the determination of OLZ in spiked human plasma. The mean recovery was 98.62 0.24 (n 4). The method was also used for stability studies of FPZ HCl upon oxidation with hydrogen peroxide, and the kinetics of the reaction were studied. A proposal for the reaction pathway was postulated.

Second-Derivative Synchronous Fluorescence Spectroscopy for the Simultaneous Determination of Cinnarizine and Nicergoline in Pharmaceutical Preparations

A rapid, simple, and highly sensitive second-derivative synchronous fluorometric method has been developed for the simultaneous analysis of binary mixtures of cinnarizine (CN) and nicergoline (NIC). The method is based upon measurement of the native fluorescence of these drugs at constant wavelength difference () = 80 nm in aqueous methanol (50, v/v). The different experimental parameters affecting the native fluorescence of the studied drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the range of 0.0251.5 and 0.255.5 g/mL for CN and NIC, respectively, with lower detection limits of 0.58 and 0.82 ng/mL and quantitation limits of 1.93 and 2.73 ng/mL for CN and NIC, respectively. The proposed method was successfully applied for the determination of the studied compounds in synthetic mixtures and in commercial tablets. The results obtained were in good agreement with those obtained with reference methods. The high sensitivity attained by the proposed method allowed the determination of CN in real and spiked human plasma. The mean recovery in the case of spiked human plasma [number of trials (n) = 3] was 102.82 2.17, while that in real human plasma (n = 3) was 105.25 2.05.

Second Derivative Synchronous Fluorescence Spectroscopy for the Simultaneous Determination of Metoclopramide and Pyridoxine in Syrup and Human Plasma

A rapid, simple, and highly sensitive second derivative synchronous fluorometric method has been developed for the simultaneous determination of metoclopramide (MT) and pyridoxine (PY) in a binary mixture. The method is based on measurement of the native fluorescence of these drugs at = 80 nm in methanol. The different experimental parameters affecting the native fluorescence of the drugs were carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges of 0.020.4 and 0.12 g/mL for MT and PY, respectively. The limits of detection were 0.003 and 0.007 g/mL and the limits of quantification were 0.008 and 0.02 g/mL for MT and PY, respectively. The proposed method was successfully applied to the determination of MT and PY in synthetic mixtures and in commercial syrup. The results were in good agreement with those obtained with a reported method. The high sensitivity attained by the proposed method allowed the determination of MT in spiked and real human plasma samples. The mean percent recoveries of MT from spiked and real human plasma (n = 3) were 93.72 3.15 and 89.72 2.19, respectively.

Spectrofluorometric Determination of Verapamil Hydrochloride in Pharmaceutical Preparations and Human Plasma Using Organized Media: Application to Stability Studies

A highly sensitive spectrofluorometric method was developed for the determination of verapamil hydrochloride (VP HCl) in pharmaceutical formulations and biological fluids. The proposed method is based on investigation of the fluorescence spectral behavior of VP HCl in micellar systems, such as sodium dodecyl sulfate (SDS) and β-cyclodextrin (β-CD). In aqueous solutions of borate buffer of pH 9 and 8.5, VP HCl was well incorporated into SDS and β-CD, respectively, with enhancement of its native fluorescence. The fluorescence was measured at 318 nm after excitation at 231 nm. The fluorescence intensity enhancements were 183 and 107% in SDS and in β-CD, respectively. The fluorescence-concentration plots were rectilinear over the range of 0.020.2 and 0.020.25 μg/mL, with lower detection limits of 5.58 × 103 and 3.62 × 103 μg/mL in SDS and β-CD, respectively. The method was successfully applied to the analysis of commercial tablets and the results were in good agreement with those obtained with the official method. The method was further applied to the determination of VP HCl in real and spiked human plasma. The mean % recoveries in the case of spiked human plasma (n 4) was 92.59 3.11 and 88.35 2.55 using SDS and β-CD, respectively, while that in real human plasma (n 3) was 90.17 6.93 and 89.17 6.50 using SDS and β-CD, respectively. The application of the method was extended to the stability studies of VP HCl after exposureto ultraviolet radiation and upon oxidation with hydrogen peroxide.

Spectrofluorometric Determination of Fluvoxamine in Dosage Forms, Spiked Plasma, and Real Human Plasma by Derivatization with Fluorescamine

A sensitive, simple, and selective spectrofluorometric method was developed for the determination of fluvoxamine (FXM) in pharmaceutical formulations and biological fluids. The method is based upon the reaction between the drug and fluorescamine in borate buffer of pH 8.0 to yield a highly fluorescent derivative that is measured at 481 nm after excitation at 383 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The method was applied for the determination of the drug over the concentration range of 0.11.1 μg/mL with a detection limit of 0.01 μg/mL (2 10-8 M). The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using a reported spectrophotometric method. The method was applied for the determination of FXM in spiked human plasma with recovery (n = 4) of 97.32 1.23%, while that in real human plasma (n = 3) was 90.79 2.73%. A proposal for the reaction pathway is presented.

Micellar Enhanced Spectrofluorometric Determination of Labetalol Through Complexation with Aluminium(III): Application to Dosage Forms and Biological Fluids

Two simple, sensitive, and specific spectrofluorometric procedures have been developed for the determination of labetalol (LBT) in pharmaceuticals and biological fluids. LBT was found to react with Al3+ , both in acetate buffer of pH 4.5 (Procedure I) and borate buffer of pH 8.0 (Procedure II), to produce highly fluorescent stable complexes. The fluorescence intensity could be enhanced by the addition of sodium dodecyl sulfate, resulting in 3.5- and 2.7-fold increases in the fluorescence intensity for Procedures I and II, respectively. In both procedures, the fluorescence intensity was measured at 408 nm after excitation at 320 nm. The different experimental parameters affecting the development and stability of the fluorescent products were carefully studied and optimized. The fluorescence intensity-concentration plots were rectilinear over the range of 0.020.1 and 0.010.05 g/mL with a detection limit of 0.003 and 0.001 g/mL for Procedures I and II, respectively. The proposed method was successfully applied to commercial tablets containing LBT. The results were in good agreement with those obtained using a reference spectrofluorometric method. Furthermore, the method was applied for the determination of LBT in spiked human plasma, and the recovery (n = 4) was 93.30 2.62%. A proposal of the reaction pathway was postulated for Procedures I and II, respectively.

Kinetic Spectrophotometric Determination of Ethamsylate in Dosage Forms

A simple and sensitive kinetic method has been developed for the determination of ethamsylate (ESL) in its pharmaceutical preparations. The method is based upon oxidation of ESL with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in presence of cerium(IV) ammonium sulfate at room temperature for 20 min. The absorbance of the reaction product is measured at 514 nm. The absorbance-concentration plot was rectilinear over the range of 430 g/mL (r = 0.9999). The lower detection limit was 0.267 g/mL (9.110 106 M) and the lower quantitation limit was 0.808 g/mL. The different experimental parameters affecting the development and stability of the reaction product were studied and optimized. The proposed method was applied to the determination of ESL in formulations, and the results obtained were in good agreement with those obtained using a reference method. The proposed method was also used for the in vitro detection of ESL in spiked human plasma at its therapeutic concentration level.

Spectrofluorimetric and Spectrophotometric Determination of Gliclazide in Pharmaceuticals by Derivatization with 4-Chloro-7-nitrobenzo-2-oxa-1,3-diazole

Accurate, sensitive, and simple spectrophotometric and spectrofluorimetric methods were developed for the determination of gliclazide in pharmaceutical formulations and biological fluids. Both methods are based on a coupling reaction between gliclazide and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in borate buffer, pH 7.8, in which a yellow reaction product that can be measured spectrophotometrically at 400 nm was developed. The same product exhibited a yellow fluorescence at 470 nm upon excitation at 400 nm. The absorbance–concentration plot was rectilinear over the range of 2–20 μg/mL with minimum detectability [signal-to-noise (S/N) ratio = 2] of 0.2 μg/mL (6.18 × 10−7 M); the fluorescence–concentration plot was rectilinear over the range of 0.2–2.5 μg/mL with minimum detectability (S/N = 2) of 0.02 μg/mL (6.18 × 10−8M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. Both methods were successfully applied to the analysis of commercial tablets. The results were in good agreement with those obtained with the official and reference spectrophotometric methods. A proposal of the reaction pathway was presented.

Simultaneous determination of cetirizine, phenyl propanolamine and nimesulide using third derivative spectrophotometry and high performance liquid chromatography in pharmaceutical preparations

Background

The combination between cetirizine (CET), phenylpropanolamine (PPA) and nimesulide (NMS) under trade name Nemeriv Cp tablet is prescribed for nasal congestion, cold, sneezing, and allergy. Among all published methods for the three drugs; there is no reported method concerning estimation of CTZ, PPA and NMS simultaneously and this motivates us to develop new and simple methods for their assay in pure form and tablet preparations.

Results

Two new methodologies were described for the simultaneous quantification of cetirizine (CTZ), PPA and NMS. Spectrophotometric procedures relies on measuring the amplitudes of the third derivative curves at 238 nm for CTZ, 218 nm for PPA and 305 nm for NMS. The calibration graphs were rectilinear over the ranges of 8–90 µg/mL for CTZ, 20–100 µg/mL for PPA and 20–200 µg/mL for NMS respectively. Regarding the HPLC method; monolithic column (100 mm × 4.6 mm i.d) was used for the separation. The used mobile phase composed of 0.1 M phosphate buffer and methanol in the ratio of 40:60, v/v at pH 7.0. The analysis was performed using UV detector at 215 nm. Calibration curves showed the linearity over concentration ranges of 5–40, 10–100 and 10–120 µg/mL for CTZ, PPA and NMS.

Conclusion

Application of the proposed methods to the laboratory prepared tablets was carried out successfully. The results were compared with those obtained from previously published methods and they were satisfactory.Graphical abstract

Validated spectrofluorimetric method for the determination of clonazepam in pharmaceutical preparations

A simple, highly sensitive and validated spectrofluorimetric method was applied in the determination of clonazepam (CLZ). The method is based on reduction of the nitro group of clonazepam with zinc/CaCl2, and the product is then reacted with 2-cyanoacetamide (2-CNA) in the presence of ammonia (25%) yielding a highly fluorescent product. The produced fluorophore exhibits strong fluorescence intensity at ʎ(em) = 383 nm after excitation at ʎ(ex) = 333 nm. The method was rectilinear over a concentration range of 0.1-0.5 ng/mL with a limit of detection (LOD) of 0.0057 ng/mL and a limit of quantification (LOQ) of 0.017 ng/mL. The method was fully validated and successfully applied to the determination of CLZ in its tablets with a mean percentage recovery of 100.10 ± 0.75%. Method validation according to ICH Guidelines was evaluated. Statistical analysis of the results obtained using the proposed method was successfully compared with those obtained using a reference method, and there was no significance difference between the two methods in terms of accuracy and precision.

Simultaneous determination of desloratadine and montelukast sodium using second-derivative synchronous fluorescence spectrometry enhanced by an organized medium with applications to tablets and human plasma

A rapid, simple, and sensitive second-derivative synchronous fluorimetric method has been developed and validated for the simultaneous analysis of a binary mixture of desloratadine (DSL) and montelukast sodium (MKT) in their co-formulated tablets. The method is based on measurement of the synchronous fluorescence intensities of the two drugs in McIlvaine's buffer, pH 2.3, in the presence of carboxy methyl cellulose sodium (CMC) as a fluorescence enhancer at a constant wavelength difference (Δλ) of 160 nm. The presence of CMC enhanced the synchronous fluorescence intensity of DSL by 216% and that of MKT by 28%. A linear dependence of the concentration on the amplitude of the second derivative synchronous fluorescence spectra was achieved over the ranges of 0.10-2.00 and 0.20-2.00 µg/mL with limits of detection of 0.02 and 0.03, and limits of quantification of 0.05 and 0.10 µg/mL for DSL and MKT, respectively. The proposed method was successfully applied for the determination of the studied compounds in laboratory-prepared mixtures and tablets. The results were in good agreement with those obtained with the comparison method. The high sensitivity attained by the proposed method allowed the determination of MKT in spiked human plasma with average % recovery of 100.11 ± 2.44 (n = 3).

Simultaneous determination of aliskiren and hydrochlorothiazide in tablets and spiked human urine by ion-pair liquid chromatography

An alternative method for analysis of aliskiren (ALI) and hydrochlorothiazde (HCT) in combined dosage forms by ion-pair reversed phase high performance liquid chromatography was developed and validated. The pharmaceutical preparations were analyzed using a C18 column (250 mm x 4.6 mm, 3 microm) with a mobile phase consisting of 25% methanol, 50% sodium monobasic phosphate aqueous solution containing 6 mM tetrabutylammonium bromide and 25% water at pH 7.2. Isocratic analysis was performed at a flow rate of 1 mL/min and a column temperature of 30 degrees C under direct UV detection at 210 nm. Paracetamol was used as internal standard. The validation was performed according to the ICH guidelines. The proposed method was linear over the concentration range of 0.250 to 60 and 0.1 to 10 microg/mL for ALI and HCT, respectively. The limits of detection and quantitation (LOD and LOQ) were 0.075 and 0.198 microg/mL, respectively, for ALI and 0.04 and 0.062 microg/mL, respectively, for HCT. The method proved to be specific, sensitive, precise and accurate with mean recovery values of 101.1 +/- 0.32% and 100.9 +/- 0.41% for ALI and HCT, respectively. The method robustness was evaluated by means of an experimental design. The proposed method was applied successfully to spiked human urine samples with mean recoveries of 98.8 +/- 0.36% and 98.1 +/- 0.21% for ALI and HCT, respectively.

Simultaneous determination of sitagliptin and metformin in pharmaceutical preparations by capillary zone electrophoresis and its application to human plasma analysis

A novel, quick, reliable and simple capillary zone electrophoresis CZE method was developed and validated for the simultaneous determination of sitagliptin (SG) and metformin (MF) in pharmaceutical preparations. Separation was carried out in fused silica capillary (50.0 cm total length and 43.0 cm effective length, 49 μm i.d.) by applying a potential of 15 KV (positive polarity) and a running buffer containing 60 mM phosphate buffer at pH 4.0 with UV detection at 203 nm. The samples were injected hydrodynamically for 3 s at 0.5 psi and the temperature of the capillary cartridge was kept at 25 °C. Phenformin was used as internal standard (IS). The method was suitably validated with respect to specificity, linearity, limit of detection and quantitation, accuracy, precision, and robustness. The method showed good linearity in the ranges of 10–100 μg/mL and 50–500 μg/mL with limits of detection of 0.49, 2.11 μg/mL and limits of quantification of 1.48, 6.39 μg/mL for SG and MF, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixtures and co-formulated tablets without interfering peaks due to the excipients present in the pharmaceutical tablets. The method was further extended to the in-vitro determination of the two drugs in spiked human plasma. The estimated amounts of SG/MF were almost identical with the certified values, and their percentage relative standard deviation values (% R.S.D.) were found to be ≤1.50% (n = 3). The results were compared to a reference method reported in the literature and no significant difference was found statistically.

Spectrofluorimetric determination of oseltamivir phosphate through derivatization with o-phthalaldehyde. Application to pharmaceutical preparations with a preliminary study on spiked plasma samples

A simple and sensitive spectrofluorimetric method has been developed and validated for the determination of oseltamivir phosphate (OST) in pharmaceutical preparations. The method is based on the reaction between oseltamivir phosphate and o-phthalaldehyde in presence of 2-mercapto-ethanol in borate buffer, pH 10.8, to give a highly fluorescent product measured at 450 nm after excitation at 336 nm. The different experimental parameters affecting the development and stability of the reaction product were studied and optimized. The fluorescence intensity-concentration plot is rectilinear over the range 0.05-1.0 µg/mL, with a lower detection limit of 5 ng/mL and limit of quantitation of 16 ng/mL. The developed method was successfully applied to the analysis of the drug in its commercial capsules and suspension, mean recoveries of OST were 99.97 ± 1.67% and 100.17 ± 1.18%, respectively (n = 3). Statistical comparison of the results obtained by the proposed and comparison method revealed no significant difference in the performance of the two methods regarding accuracy and precision. The proposed method was further extended to in vitro determination of the studied drug in spiked human plasma as a preliminary investigation; the mean recovery (n = 3) was 98.68 ± 5.8%. A reaction pathway was postulated.