Validated spectrofluorimetric method for the determination of lamotrigine in tablets and human plasma through derivatization with o-phthalaldehyde

Selective Spectrofluorimetric Approach for the Assessment of Two Antipsychotic Drugs through Derivatization with O-Phthalaldehyde

A facile and sensible spectrofluorimetric approach for the measurement of two antipsychotic medications, aripiperazole (ARP) and clozapine (CLZ), was devised and validated. The approach involves reacting the examined medicines with o-phthalaldehyde in the presence of β-mercaptoethanol in a borate buffer of pH 9.0 and pH 10 for ARP and CLZ, respectively, to produce a robustly fluorescent compound that is detected at 450 nm following excitation at 340 nm. The experimental variables influencing the performance and product stability were thoroughly investigated and optimized. Under optimal conditions, the intensity of the fluorescence was linear during a concentration range of 0.1–0.5 μg/mL, with a limit of detection (0.0391 and 0.0400 μg/mL) and limit of quantitation (0.1035 and 0.1332 μg/mL), respectively, for ARP and CLZ. The suggested approach was successful in analyzing commercialized tablets. A statistical investigation of the results produced by the suggested and standard methods showed no remarkable variation in the precision and accuracy of the two approaches. A chemical mechanism using o-phthalaldehyde was proposed.

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.

Determination of lamotrigine by fluorescence quenching of N-doped graphene quantum dots after its solid-phase extraction using magnetic graphene oxide

A sensitive fluorescent nanoprobe is reported for the determination of lamotrigine after its preconcentration by magnetic graphene oxide nanocomposite. The fluorescent nanoprobe is based on the quenching effect of lamotrigine on the nitrogen graphene quantum dots fluorescence at 440 nm, through strong hydrogen bonding. Under optimum conditions, the quenching fluorescent intensity of nitrogen graphene quantum dots shows linearity with the lamotrigine concentration in the range of 2.0-45.0 µg L^-1, limits of detection (LOD), and quantification of 0.39 and 1.28 µg L^-1 respectively. The parameters affecting the extraction and determination of lamotrigine were optimized via the central composite design (CCD) and one at the time method, respectively. The developed method was successfully employed for the extraction and quantification of lamotrigine in biological samples.

Novel spectrofluorimetric determination of brigatinib in bulk powder and human urine samples via ion-pair complex formation using eosin Y

The developed spectrofluorimetric method was successfully applied to the analysis of brigatinib (BRG) in its bulk powder form, and human urine sample. It is based on the investigation of the fluorescence spectrum behavior of the BRG-eosin Y complex. The relative fluorescence intensity (RFI) was recorded at 560 nm after excitation at 480 nm. The principle of the proposed method was thoroughly explained. All experimental parameters affecting method development were optimized. Moreover, the obtained results were fully discussed and statistically analyzed. The molar ratio method was applied to study the stoichiometric relationship between BRG and eosin Y complex. The method revealed a ratio of 1:3 for BRG-eosin Y afforded the highest RFI. The developed method was validated over the concentration range of 62.5-4000 ng mL^-1. The results were compared positively with the reported method.

Lamotrigine-A Review of Analytical Methods Developed for Pharmaceutical Formulations and Biological Matrices

Lamotrigine owing to its excellent inhibitory property of neurotransmitter release especially glutamate is used in the treatment of epilepsy as a second-line antiepileptic drug. It differs from other antiepileptic drugs chemically and pharmacologically and is used as both monotherapy and adjunct therapy in the treatment of epilepsy. The present review focuses on two aspects (a) various analytical methods used in quantification of Lamotrigine in pharmaceutical formulations and (b) various analytical methods used to determine Lamotrigine in biological matrices. Here the various analytical methods are developed using different parameters and validation of employed methods is discussed. Estimated parameters like the linearity, LOD (Limit of detection) and LOQ (Limit of quantification) of validation are discussed for the individual method. The critical quality attributes like the wavelength of detection, mobile phase, columns, flow rate, retention time, and the sample preparation methods for the estimation of Lamotrigine by bioanalytical methods are also discussed.

Validated Microwell-Based Spectrofluorimetric Method for Quantification of Ravidasvir (New Anti-Chronic Hepatitis C Virus-GT4) in Rat Plasma and Its Application to Pharmacokinetic Study

Background

Ravidasvir (RAV) has been regarded as a potent new NS5A inhibitor with a magnificent safety and tolerability in the management of genotype 4 hepatitis C virus (HCV) patients. Suitable analytical techniques are needed for the measurement of RAV in different biological matrices.

Methods

We have developed a fast, sensitive and economical 96-microwell-based spectrofluorimetric technique combined with one-step protein precipitation extraction strategy for the measurement of RAV in rat plasma.

Results

Under the optimum conditions, the direct relationship in rat plasma was accomplished between the RAV concentrations and the fluorescence (FL) intensity in a scope of 2.5–200 ng/mL with 0.9998 and 0.9999 for the quantification and correlation coefficients, respectively. The lower limit of detection (LLOD) was 0.840 ng/mL and this demonstrates the high sensitivity of the proposed assay. The accuracy (RE%) ranged from 95.34% to 102.29%, and the precision (RSD%) was less than 3.59%. The recovery was ranged from 93.12% to 96.26%. The stability of RAV in rat plasma was carried out and established its good stability in the range of room conventional temperature and at long-term stability (−80°C, 30 days). The developed technique was validated as stated by the United States Food and Drug Administration (US-FDA) guidelines for bioanalytical technique verification.

Conclusion

The approved technique was effectively applied for a pharmacokinetic (PK) study after single oral gavage administration of RAV at a dose of 35 mg/kg and it could be presumed that the proposed assay can be applied to clinical trials.

A highly sensitive fluorimetric protocol based on isoindole formation for determination of gabapentin

A new, simple, highly sensitive and selective spectrofluorimetric method was developed for determination of gabapentin through its derivatization witho-phthalaldehyde in the presence of 2-mercaptoethanol.

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

A new, selective and sensitive spectrofluorimetric method was designed for the quantitation of doxazosin (DOX), terazosin (TER) and alfuzosin (ALF) in their dosage forms and human plasma. The method adopts efficient derivatization of the studied drugs with ortho-phthalaldehyde (OPA), in the presence of 2-mercaptoethanol in borate buffer (pH9.7) to generate a highly fluorescent isoindole derivatives, which can strongly enhance the fluorescence intensities of the studied drugs, allowing their sensitive determination at 430nm after excitation at 337nm. The fluorescence-concentration plots were rectilinear over the ranges (10.0-400.0) ng/mL. Detection and quantification limits were found to be (0.52-3.88) and (1.59-11.76) ng/mL, respectively. The proposed method was validated according to ICH guidelines, and successfully applied for the determination of pharmaceutical preparations of the studied drugs. Moreover, the high sensitivity of the proposed method permits its successful application to the analysis of the studied drugs in spiked human plasma with % recovery (96.12±1.34-100.66±0.57, n=3). A proposal for the reaction mechanism was presented.

A new method to determine the new C-Met inhibitor “Cabozantinib” in dosage form and human plasma via micelle-enhanced spectrofluorimetry

A highly sensitive and simple micelle-enhanced spectrofluorimetric method was developed for the determination of cabozantinib (CBZ) in its pharmaceutical formulation and spiked human plasma without any derivatization.

Stress Degradation Assessment of Lamotrigine Using a Validated Stability-Indicating HPTLC Method

In this work, a sensitive and stability-indicating HPTLC method for the determination of lamotrigine is presented. According to the International Conference on Harmonization guidelines Q1A, lamotrigine was exposed to a variety of stress conditions; these include heating in acidic, basic and neutral media. Its stability towards oxidative stress, humidity, high temperature and direct sunlight was also examined. Separation of the drug from its forced degradation impurities was achieved using TLC silica gel plates and a mobile phase composed of ethyl acetate: methanol: ammonia. The linear regression analysis of the data obtained for the correlation plots showed good linearity over the concentration range of 10–300 ng/spot. The forced degradation studies showed that lamotrigine is susceptible to degradation under acidic, basic, neutral and oxidative conditions, among which alkaline-induced hydrolysis had the highest degradative potential. Alternatively, the drug was stable under heat, humidity, and daylight stress factors. In order to assess the purity and stability of the drug in tablet formulations, the developed method was applied to the analysis of commercial tablets in brand and generic products. The obtained results showed that the degradation of the drug has not occurred in the marketed formulations that were analyzed by the described methodology.

Development and validation of a spectrofluorimetric method for the determination of erlotinib in spiked human plasma

A rapid and sensitive spectrofluorimetric method was developed and validated for the determination of erlotinib (ETB), a potent anticancer drug, in spiked human plasma without any derivatization. The described method was validated and the analytical parameters of linearity, accuracy, precision (intra- and inter-day), limit of detection (LOD), and limit of quantification (LOQ) were evaluated. The relation between the fluorescence intensity and concentration was found to be linear (r(2) 0.9998) over the range 125 to 1000 ng/mL with the detection limit of 15 ng/mL. A simple liquid-liquid extraction method was followed in order to extract the drug from spiked plasma. The mean absolute recoveries of ETB were 85.59 % (±0.57), 86.91 % (±1.77) and 89.31 % (±3.01) at spiked plasma ETB concentration of 5000, 3750 and 2500 ng/mL, respectively. The spectrofluorimetric method presented here is a rapid, simple, specific, and reproducible method and can be used to characterize the plasma pharmacokinetics of ETB.

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.

Highly sensitive voltammetric determination of lamotrigine at highly oriented pyrolytic graphite electrode

The electrochemical behavior of lamotrigine (LMT) at the pyrolytic graphite electrode (PGE) is investigated in detail by the means of cyclic voltammetry. During the electrochemical reduction of LMT, an irreversible cathodic peak appeared. Cyclic voltammetric studies indicated that the reduction process has an irreversible and adsorption-like behavior. The observed reduction peak is attributed to a two-electron process referring to the reduction of azo group. The electrode showed an excellent electrochemical activity toward the electro-reduction of LMT, leading to a significant improvement in sensitivity as compared to the glassy carbon electrode. The results of electrochemical impedance spectroscopy and cyclic voltammetry showed that edge-plane pyrolytic graphite electrode has excellent electrochemical response properties toward LMTs with respect to glassy carbon electrode modified with carbon nanotubes. High sensitivity, low detection limit and very good repeatability together with excellent recovery make the electrode as a powerful devise for accurate determination of LMT in pharmaceutical and biological samples.