Fast concurrent determination of guaifenesin and pholcodine in formulations and spiked plasma using first derivative synchronous spectrofluorimetric approach

Guaifenesin and pholcodine are frequently co-formulated in certain dosage forms. A new fast first derivative synchronous spectrofluorometric method has been used for their simultaneous analysis in mixtures. Here, first derivative synchronous spectrofluorometry enabled the successful simultaneous estimation of guaifenesin at 283 nm and pholcodine at 275 nm using a wavelength difference (Δλ) of 40 nm. The method was fully validated following International Council of Harmonization guidelines. For guaifenesin and pholcodine, linearity was determined within the corresponding ranges of 0.05-0.30 and 0.10-6.0 μg/ml. The two drugs were effectively analyzed using the developed approach in their respective formulations, and the results showed good agreement with those attained using reference methods. The method demonstrated excellent sensitivity, with detection limits down to 0.007 and 0.030 μg/ml and quantitation limits of 0.020 and 0.010 μg/ml for guaifenesin and pholcodine, respectively. Therefore, the procedure was successful in determining these drugs simultaneously in vitro in spiked plasma samples and syrup dosage form. The developed methodology also offered an environmentally friendly advantage by utilizing water as the optimal diluting solvent throughout the whole work. Different greenness approaches were investigated to ensure the method's ecofriendly properties.

A validated ecofriendly chromatographic method for determination of myasthenia gravis combined medications in spiked human plasma

Recently, the main interest of analytical chemistry researchers has been the development of green analytical methods to minimize harmful effects on the environment and natural life. Therefore, an RP-HPLC method was developed and assessed regarding its greenness criteria using three greenness assessment tools: an analytical eco-scale, an analytical greenness metric approach and a green analytical procedure index. This method aims to separate and quantitatively determine three co-administered drugs, namely pyridostigmine bromide (PYR), 6-mercaptopurine (MRC) and prednisolone (PRD), in their tertiary mixture and spiked human plasma. These drugs are co-administered to manage myasthenia gravis autoimmune disease. The separation was done using a C₁₈ column and a gradient elution of a mixture of 0.1% H₃ PO₄ aqueous solution (pH 2.3) and methanol. The flow rate was adjusted to 1 ml/min and detection was done at 254 (for PYR and PRD) and at 330 nm (for MRC). The lower limits of quantitation were 15, 2, and 5 μg/ml for PYR, MER and PRD, respectively. Linear correlations were obtained and found to be near 1. In addition, the proposed method was validated according to the US Food and Drug Administration's instructions, and the results proved its success to determine the three studied drugs in their tertiary mixture and spiked human plasma.

Development and Validation of a Method for Quantification of Favipiravir as COVID-19 Management in Spiked Human Plasma

In the current work, a simple, economical, accurate, and precise HPLC method with UV detection was developed to quantify Favipiravir (FVIR) in spiked human plasma using acyclovir (ACVR) as an internal standard in the COVID-19 pandemic time. Both FVIR and ACVR were well separated and resolved on the C18 column using the mobile phase blend of methanol:acetonitrile:20 mM phosphate buffer (pH 3.1) in an isocratic mode flow rate of 1 mL/min with a proportion of 30:10:60 %, v/v/v. The detector wavelength was set at 242 nm. Maximum recovery of FVIR and ACVR from plasma was obtained with dichloromethane (DCM) as extracting solvent. The calibration curve was found to be linear in the range of 3.1-60.0 µg/mL with regression coefficient (r2) = 0.9976. However, with acceptable r2, the calibration data's heteroscedasticity was observed, which was further reduced using weighted linear regression with weighting factor 1/x. Finally, the method was validated concerning sensitivity, accuracy (Inter and Intraday's % RE and RSD were 0.28, 0.65 and 1.00, 0.12 respectively), precision, recovery (89.99%, 89.09%, and 90.81% for LQC, MQC, and HQC, respectively), stability (% RSD for 30-day were 3.04 and 1.71 for LQC and HQC, respectively at -20 °C), and carry-over US-FDA guidance for Bioanalytical Method Validation for researchers in the COVID-19 pandemic crisis. Furthermore, there was no significant difference for selectivity when evaluated at LLOQ concentration of 3 µg/mL of FVIR and relative to the blank.

Design and strategy for spectrofluorimetric determination of tranexamic acid in its authentic form and pharmaceutical preparations: application to spiked human plasma

A creative, very sensitive and noncomplicated spectrofluorimetric technique was established and further validated to determine tranexamic acid in both its authentic form and its pharmaceutical preparation dosage forms. In the introduced technique, a reaction was found between the aliphatic primary amino group of tranexamic acid and ninhydrin/phenylacetaldehyde reagents in the presence of Torell and Steinhagen buffer pH 7.0, which led to the production of a highly fluorescent product; fluorescence intensity was measured at 475 nm after excitation at 391 nm. A calibration curve was drawn with a linear range of 0.3-2 μg/ml. Limit of detection and limit of quantification values were 0.051 and 0.155 μg/ml respectively. The introduced technique was validated based on the International Council for Harmonisation guidelines and agreed for determination of tranexamic acid in its pharmaceutical formulation. Finally, this simple method was also applied for determination of tranexamic acid in spiked human plasma.

Green spectrofluorimetric determination of salmeterol xinafoate in its pure forms, medicinal commercial formula, and human plasma: Application for stability studies

A natural, accurate, extremely rapid, and precise spectrofluorometric method has been developed and validated for determination of salmeterol (SAL) xinafoate in its medicinal commercial form and spiked human plasma. The native SAL fluorescence has been measured at 415 nm (after 340 nm as excitation) in distilled water. Different factors affecting the native fluorescence consistency of SAL were surveyed and optimized. The suggested procedure was capable of SAL determination over concentrations ranging 200-2000 ng.mL^-1 with excellent correlation coefficient of 0.9995. The limits of detection and quantification were estimated as 44.44 ng mL^-1 and 134.66 ng mL^-1 , respectively. The method has good accuracy and precision. The green spectrofluorometric method was used for determination of SAL in its commercial preparations and the results were in accordance with other reported methods regarding accuracy and precision. Moreover, the proposed procedure was enforced for stability indicating assay of SAL and for SAL determination in spiked human plasma. Nearly no cost, high sensitivity, and wide application make the proposed method ideally suited for analysis of SAL in quality control laboratories.

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.

Combining derivative and synchronous approaches for simultaneous spectrofluorimetric determination of terbinafine and itraconazole

In this study, determination of terbinafine and itraconazole down to biological concentration level has been carried out. The determination is based on increasing the selectivity of the spectrofluorimetric technique by combining both derivative and synchronous spectrofluorometric approaches, which permits successful estimation of terbinafine at 257 nm and itraconazole at 319 nm in the presence of each other at Δλ of 60 nm. International Conference on Harmonization validation guidelines were followed to fully validate the method, and linearity was obtained for the two drugs over the range of 0.1-0.7 µg ml-1 for terbinafine and 0.5-4.0 µg ml-1 for itraconazole. Application of the method was successfully carried out in the commercial tablets with good agreement with the comparison spectrofluorometric methods. As the detection limits were down to 0.013 and 0.1 µg ml-1 and quantitation limits were 0.04 and 0.032 µg ml-1 for terbinafine and itraconazole, respectively; the in vitro determination of terbinafine and itraconazole in spiked plasma samples was applicable. The percentage recoveries in biological samples were 97.17 ± 4.54 and 98.75 ± 2.25 for terbinafine and itraconazole, respectively. Water was used as the optimum diluting solvent in the proposed methodology which adds an eco-friendly merit.

First derivative synchronous spectrofluorimetric method for the simultaneous determination of propofol and cisatracurium besylate in biological fluids

Propofol and cisatracurium besylate have been simultaneously determined using a highly sensitive first derivative synchronous spectrofluorometric method. The method is based on measuring first derivative synchronous spectrofluorimetric amplitude at Δλ = 40 nm with a scanning rate of 600 nm/min. The different experimental parameters affecting the fluorescence intensity of the two drugs were carefully studied and optimized. The amplitude-concentration plots were rectilinear over the range 40.0-400.0 ng/mL and 20.0-280.0 ng/mL for propofol and cisatracurium, respectively with lower detection limits of 4.0 and 2.35 ng/mL and quantification limits of 12.1 and 7.1 ng/mL for propofol and cisatracurium, respectively. The proposed method was successfully applied for the determination of the two compounds in synthetic mixtures and in commercial ampoules. The high sensitivity attained using the proposed method allowed the simultaneous determination of both drugs in spiked plasma samples. The mean % recoveries in spiked human plasma (n = 3) were 96.53 ± 0.90 and 96.20 ± 1.64 for each of propofol and cisatracurium, respectively. The method was validated in compliance with International Council of Harmonization (ICH) Guidelines.

Highly sensitive spectrofluorimetric method for rapid determination of orciprenaline in biological fluids and pharmaceuticals

Orciprenaline sulphate (ORP) is a direct-acting sympathomimetic with mainly beta-adrenoceptor stimulant activity. It is used as a bronchodilator in the management of reversible airway obstruction. For the first time, a rapid highly sensitive spectrofluorimetric method is described that is relied on measuring the fluorescence spectra of ORP at acidic pH and without addition of any chemical reagents. The relative fluorescence intensity was measured at 310 nm and after excitation at 224 nm. ORP native fluorescence was calibrated in both water and acetonitrile as diluting solvents. The method was designed to estimate the drug in miscellaneous matrices with high accuracy and precision. Linear ranges of calibration curves were 30.0-400.0 ng/ml and 10.0-240.0 ng/ml in water and acetonitrile, respectively. The detection limits were calculated and reached as low as 3.3 and 3.1 ng/ml, respectively, representing the ultra-sensitivity of the proposed method. This result permitted application of this method for spiked human plasma and urine and was used as a preliminary investigation with good percentage recovery (89.4-106.8%). The application was further extended to analyse ORP in its pharmaceutical formulations. The method was validated in compliance with International Council of Harmonization (ICH) Guidelines.

Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma

A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λem 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4-40 and 10-250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test.

Determination of sulpiride in pharmaceutical preparations and biological fluids using a Cr (III) enhanced chemiluminescence method

A highly sensitive and simple method for identifying sulpiride in pharmaceutical formulations and biological fluids is presented. The method is based on increased chemiluminescence (CL) intensity of a luminol-H2O2 system in response to the addition of Cr (III) under alkaline conditions. The CL intensity of the luminol-H2O2-Cr (III) system was greatly enhanced by the addition of sulpiride and the CL intensity was proportional to the concentration of sulpiride in a sample solution. Various parameters affecting the CL intensity were systematically investigated and optimized for determination of the sulpiride in a sample. Under the optimum conditions, the CL intensity was proportional to the concentration of sulpiride in the range of 0.068-4.0 µg/mL, with a good correlation coefficient of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 8.50 × 10(-6) µg/mL and 2.83 × 10(-5) µg/mL, respectively. The method presented here produced good reproducibility with a relative standard deviation (RSD) of 2.70% (n = 7). The effects of common excipients and metal ions were studied for their interference effect. The method was validated statistically through recovery studies and successfully applied for the determination of sulpiride in pure form, pharmaceutical preparations and spiked human plasma samples. The percentage recoveries were found to range from 99.10 to 100.05% for pure form, 98.12 to 100.18% for pharmaceutical preparations and 97.9 to 101.4% for spiked human plasma.

Spectrofluorimetric method for the determination of sulpiride in pharmaceutical preparations and human plasma through derivatization with 2-cyanoacetamide

A sensitive and accurate spectrofluorimetric method has been developed for the determination of sulpiride in pharmaceutical preparations and human plasma. The developed method is based on the derivatization reaction of 2-cyanoacetamide with sulpiride in 30% ammonical solution. The fluorescent derivatized reaction product exhibited maximum fluorescence intensity at 379 nm after excitation at 330 nm. The optimum conditions for derivatization reactions were studied and the fluorescence intensity versus concentration plot was found to be linear over the concentration range 0.2-20.0 µg/mL with a correlation coefficient of 0.9985. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.82 and 2.73 ng/mL, respectively. The proposed method was validated according to ICH guidelines. The effects of common excipients and co-administered drugs were also studied. The accuracy of the method was checked using the standard addition method and percent recoveries were found to be in the range of 99.00-101.25% for pharmaceutical preparations and 97.00-97.80% for spiked human plasma. The method was successfully applied to commercial formulations and the results obtained for the proposed method were compared with a high-performance liquid chromatography reference method and statistically evaluated using the Student's t-test for accuracy and the variance ratio F-test for precision. A reaction pathway was also proposed.