Derivatization of labetalol hydrochloride for its spectrofluorimetric and spectrophotometric determination inhuman plasma: Application to stability study

A nano-level assay of tizanidine using the fluorogenic character of benzofurazan derivative: Application to plasma, tablets, and content homogeneity evaluation

People frequently administer Tizanidine (TIZ) to treat spasticity resulting from diseases like multiple sclerosis or spinal cord injuries. It also helps prevent muscle spasms. It helps to relax and release tense and stiff muscles by inhibiting specific nerve signals in the brain and spinal cord. The technique employed in this study made use of the unique ability of benzofurazan to confer fluorescent character when reacted with TIZ at specific conditions. This fluorogenic property was harnessed to evolve a remarkably sensitive, affordable, and selective method to quantify TIZ. The resulting yellow fluorescent product was observedat a wavelength beam of 532.9 nm, and an excitation wavelength beam of 474.9 nm was applied. By looking at the response across the TIZ concentration, the calibration chart's linearity was assessed in the range of 40-500 ng/mL. By computation, the approach's detection level (LOD) was determined to be 11.9 ng/mL, while the quantitation level was approximated to be 36 ng/mL. All pertinent factors impacting the strategy's efficacy were thoroughly inspected and adjusted accordingly. The proposed strategy was validated following the guidelines outlined by the ICH. The outcomes confirmed the method's capability for the accurate quantifying of TIZ in tablets, spiked plasma, and pharmaceutical assessing content uniformity.

Dual benefits of NBD-Cl fluorogenic action and sample pretreatment (SALLE) technology in the assessment of anticoagulant medication: Dabigatran in pharmaceutical capsules and plasma samples

Dabigatran (DBG), marketed as Pradaxa, is an anticoagulant medication prescribed for the treatment and mitigation of blood clots and to lower the risk of stroke in individuals with the heart condition known as atrial fibrillation. This medication is specifically indicated for preventing blood clots post hip or knee replacement surgeries and in patients with a prior history of clots. Compared to warfarin, dabigatran serves as a viable alternative that does not necessitate routine blood monitoring tests. The complimentary benefits associated with SALL (salting-out assisted liquid-liquid extraction) and the fluorogenic capabilities of benzofurazan. These methods were combined to provide an affordable and sensitive DBG assaying method. The spectral strength of the yellow luminous product was examined at 533.8 nm and by adjustment of a wavelength of 474.7 nm for excitation. To assess its linearity, the calibration chart was tested across a DBG concentration range of 30-500 ng/ml. Via accurate computation based on ICH, the detection limit (LD) was determined to be 9.5 ng/ml, and the strategy can quantify the DBG to a limit of 28 ng/ml. To ensure success, various crucial parameters for method implementation have been extensively studied and adapted. The validation of the strategy adhered to the policies outlined by ICH, affirming its precision in quantifying DBG in capsules. Furthermore, the inclusion of SALLE steps facilitated accurate monitoring of DBG in plasma samples, introducing a unique and advanced methodology for analyzing this compound in biological samples.

Development of fluorescence probe for spectrofluorimetric determination of viloxazine hydrochloride in pharmaceutical form and rat plasma; additional pharmacokinetic study

Attention deficit hyperactivity disorder (ADHD) is a neurological condition frequently identified in early childhood and frequently co-occurs with other neuropsychological disorders, particularly autism. Viloxazine hydrochloride, a non-stimulant medication, has recently gained approval for treating attention-deficit hyperactivity disorder. This paper describes the first spectrofluorimetric method for precisely measuring the content of viloxazine in pharmaceutical capsules and rat plasma. This method employed NBD-Cl (4-chloro-7-nitrobenzo-2-oxa-1,3-diazole) as a fluorescent probe, which transformed viloxazine in an alkaline environment into a remarkably sensitive fluorescent adduct. Upon excitation at 476 nm, this adduct becomes detectable at a wavelength of 536 nm. The method was validated using ICH criteria, revealing acceptable linearity across a concentration range of 200-2000 ng/ml and high sensitivity with LOD and LOQ values of 46.774 ng/ml and 141.741 ng/ml, respectively. This method was adeptly applied in a pharmacokinetic study of viloxazine in rat plasma following a single oral dose (10 mg/kg), yielding a mean peak plasma concentration (Cmax) of 1721 ng/ml, achieved within 1.5 h. Furthermore, the environmental impact of the technique was assessed using two greenness assessment tools, revealing a notable level of eco-friendliness and sustainability.

Synergistic utility of NBD-Cl fluorogenic loading activity and salting-out assisted liquid-liquid extraction as sample pretreatment in rasagiline tracking in different matrices

A typical drug used to treat Parkinson's disease is called rasagiline. It belongs to an assortment of drugs known as monoamine oxidase inhibitors, which function by raising dopamine levels in the brain. This work created a unique spectrofluorimetric method for the analytical assay of rasagiline for the first time. The approach utilized the synergistic utility of the fluorogenic properties of benzofurazan and salting-out assisted liquid-liquid extraction. By combining these techniques an ultrasensitive, and highly selective methodology for the assay of rasagiline was established. Measurements were made of the resultant yellow fluorescent product at 533 nm by applying an excitation wavelength of 475.3 nm. The calibration graph was examined to assess its linearity across a range of 30-600 ng/ml. Through estimation, the limit of detection was discovered to be 8.9 ng/ml, while the quantitation limit was estimated to be 27 ng/ml. All relevant parameters influencing the fulfillment of the developed method were thoroughly examined and tuned. Following the directives set by the (ICH) the suggested approach was confirmed and demonstrated its capability for the accurate determination of rasagiline in tablets, as well as for testing content uniformity. The incorporation of salting-out assisted liquid-liquid extraction technology enables effective tracking of rasagiline in plasma samples, providing a novel and innovative approach for its analysis in biological matrices.

Two facile approaches based on association complex with erythrosine-B for nano-level analysis of duloxetine: application to content uniformity

Duloxetine is an antidepressant that exhibits its action by preventing the reuptake of serotonin and norepinephrine by neurons. In this analytical study, we developed two facile, sensitive methods for duloxetine analysis. Both methods rely on the formation of binary association complex between erythrosine-B and duloxetine in an acidic medium using spectrofluorimetric and resonance Rayleigh scattering (RRS) techniques. Spectrofluorimetric method simply uses the quenching property of the formed complex on the native fluorescence of erythrosine-B at an emission wavelength of 557.2 nm (λ ex = 528.6), while RRS is based on detecting the enhancement in the RRS signal at 357.2 nm. The proposed methods have been validated according to the International Conference on Harmonization guidelines. The approaches provide linear assay of duloxetine hydrochloride over 0.1-2.4 µg ml-1 and 0.2-2.0 µg ml-1 for spectrofluorimetric and RRS methods, respectively. Variables affecting methods and complex formation were studied and optimized. The limit of detection values were 0.03 and 0.056 µg ml-1 for spectrofluorimetric and RRS methods, respectively. Both approaches were applied with acceptable results for formulation analysis and evaluation of cymbatex capsule content uniformity.

Investigation of the association complex formed between dapoxetine and erythrosine-B for facile dapoxetine assay in pharmaceutical formulation using resonance Rayleigh scattering and spectrofluorimetric techniques

Premature ejaculation is a male sexual problem that is marked by rapid ejaculation and quick attainment of orgasm. Dapoxetine belongs to the antidepressant category and modulates its action by preventing the reuptake of serotonin by neurons. Dapoxetine is marketed as an off-label therapy for premature ejaculation. Here, two facile, sensitive, and green compatible approaches were established for dapoxetine assay. The approaches chemically rely on association complex formed between erythrosine-B and dapoxetine in an acidic buffered medium. The quenching effect of the formed complex on the native erythrosine fluorescence at emission 553.5 nm is simply the main idea of spectrofluorimetric assay, while resonance Rayleigh scattering methodology uses augmentation of resonance Rayleigh scattering spectrum at 345 nm by the added dapoxetine. The current approaches exhibit linearity between response and dapoxetine concentration over 0.2-2.5 μg/ml and 0.3-3.0 μg/ml for spectrofluorimetric and resonance Rayleigh scattering (RRS) methods, respectively. All variables affecting methods and complex formation were studied and precisely optimized. The criteria of validation were performed by the directives provided by International Conference on Harmonization's (ICH) Guidelines and limits of detection were 0.06 and 0.05 μg/ml for spectrofluorimetric and RRS techniques, respectively. Finally, the approaches were applied with acceptable results for pharmaceutical formulation analysis.

Utility of 4-chloro-7-nitrobenzofurazan for spectrofluorimetric and spectrophotometric determinations of the anti-hirsutism agent (α-difluoromethylornithine) in pharmaceutical cream samples

α-Difluoromethylornithine is an effective medication for the treatment of African Trypanosomiasis and widely distributed for the treatment of hirsutism. This work provides an adequate analytical protocol for the spectrophotometric and the spectrofluorimetric determination of α-difluoromethylornithine through its interaction with 4-chloro-7-nitrobenzofurazan (NBD-chloride) reagent. After optimization of the reaction conditions (NBD-chloride volume, buffer volume, the best diluting solvent, heating time and temperature and pH of the medium) the reaction product was measured spectrophotometrically at λ_max = 478 nm and spectrofluorimetrically at λ_emission = 540 nm after λ_excitation = 475 nm. The proposed methods were linear over the ranges 5-30 μg ml^-1 and 0.4-2 μg ml^-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Moreover, the proposed work offers an adequate sensitive and selective determination for α-difluoromethylornithine where the detection limits were 0.90 μg ml^-1 and 0.071 μg ml^-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Furthermore, both methods were successfully applied for the quantification of α-difluoromethylornithine in the pharmaceutical cream samples with acceptable recovery results.

Fast fabric phase sorptive extraction of selected β-blockers from human serum and urine followed by UHPLC-ESI-MS/MS analysis

A fast fabric phase sorptive extraction method is presented herein for the rapid isolation of selected beta-blocker drugs from human serum and urine. Among many high efficiency sol-gel sorbent coated FPSE membranes, sol-gel CW20 M coated FPSE membrane was identified as the best FPSE membrane for the target beta-blocker drugs possessing logP values ranging from 0.1 (highly polar) to 3.1 (moderately polar). Due to the engineered affinity towards the analytes via complementary intermolecular interactions and high mass transfer rate of the analytes from the bulk sample solution to the FPSE membrane, the extraction is accomplished in relatively short time (15 min) while its high permeability permits the direct extraction of biological samples without any other pretreatment. The advantages of the fabricated extraction membrane were exploited for the determination of six beta-blockers (namely atenolol, nadolol, metoprolol, oxprenolol, labetalol and propranolol) in biological matrices in combination with UHPLC-ESI-MS/MS. Important parameters including extraction time, sample volume, sorbent size, elution solvent, etc. affecting the performance of the extraction were systematically investigated. The linearity of the method was evaluated in the range of 50-5000 ng mL^-1 by constructing weighted (1/X) matrix-matched calibration curves. The intra-day and inter-day trueness were ranged between - 17.2 to 13.3% and - 10.8 to 12.6%, respectively. The intra-day and inter-day precision were less than 11.5 and 14.5 %, respectively. The proposed analytical scheme was successfully applied to the determination of the target drugs in human serum and urine.

Investigating the interaction of terbinafine with xanthenes dye for its feasible determination applying the resonance Rayleigh scattering technique

Terbinafine hydrochloride is a potent antifungal drug indicated for oral and topical treatment of mycoses. A resonance Rayleigh scattering (RRS) method was developed for the determination of terbinafine hydrochloride through a feasible complexation reaction with erythrosine B. In a weakly acidic medium (acetate buffer, pH 5.0), terbinafine hydrochloride can react with erythrosine B through the electrostatic attraction and virtue of hydrophobic force to form an ion-association complex. The reaction resulted in the appearance of a new RRS peak at 369 nm. The RRS peak was increased by increasing the concentration of terbinafine hydrochloride in the linear range of 0.1-1.5 µg ml-1. All the reaction conditions (erythrosine B concentration, buffer volume, diluting solvent and pH) were optimized. The detection limit was 0.029 µg ml-1 while the quantitation limit was 0.089 µg ml-1. The suggested method after its validation was successfully applied for the determination of terbinafine hydrochloride in different pharmaceutical formulations (tablets and cream) with sufficient recovery.

The first spectrofluorimetric approach for accurate determination of trimetazidine in its dosage forms: Application to content uniformity testing

A novel sensitive and simple spectrofluorimetric method has been developed then validated for the determination of trimetazidine in pure form and its tablets. This method is found on the reaction between trimetazidine's secondary amine moiety with NBD-Cl reagent, using borate buffer at pH 8.0 yielding a highly fluorescent product whose fluorescence intensity was measured at 526 nm (excitation at 466 nm). A calibration curve plotted showed that the linear range of the presented method was (50-700 ng/ml) with a correlation coefficient of 0.9998. The limits of detection (LOD) and limits of quantitation (LOQ) values were 15.01 and 45.50 ng/ml respectively. The presented approach was validated according to ICH guidelines and successfully applied for determining trimetazidine in its tablets with a mean percentage recovery of 99.65% ± 1.04, 99.23% ± 0.80 and 98.33% ± 1.03 for Metacardia® (20 mg), Vastor ® (20 mg) and Tricardia® (20 mg) tablets respectively. Finally, the proposed method was adopted to study the content uniformity test according to USP guidelines.

Investigating the interaction of mitoxantrone with anionic surfactants by spectrofluorimetry and its application for the feasible analysis of pharmaceutical preparation and biological fluids

The behaviour of mitoxantrone (MTX), an anthracenedione antineoplastic agent, in different types of organized medium was explored using molecular spectrofluorometry. The original fluorescence and quantum yield of MTX were augmented by about five-fold in the aqueous buffered solution (Britton-Robinson, pH 3.0) by the addition of sodium dodecyl sulfate. Enhancement in the fluorescence intensity did not come from the boost in the ultraviolet (UV) light absorbance of the drug in the presence of micelles but due to shielding of the lowest excited singlet state of the drug from a radiationless process inside the cavity of the micelle. Accordingly, a versatile, sensitive, and feasible spectrofluorimetric method was constructed and evaluated for MTX determination. Fluorescence measurements were performed at 675 nm (λ_ex 610 nm). A linear relationship was shown between fluorescence intensity and drug concentration within the range 0.01-2.0 μg ml^-1 of MTX with a correlation coefficient of 0.9999 and a detection limit of 2 ng ml^-1 . The developed method was effectively used for analysis of MTX in biological samples and dosage forms. In addition, the method was expanded to study the stability of MTX exposed to different drastic degradations and the kinetic parameters of the degradation were calculated.

New spectrofluorimetric analysis of empagliflozin in its tablets and human plasma using two level full factorial design

An efficient, accurate and sensitive spectrofluorimetric method was developed for analysis of empagliflozin (EGF) in pure form, dosage form and human plasma. The proposed procedure was based on formation of yellow fluorescent product between benzofurazan reagent and empagliflozin in slightly alkaline medium that is measured at 521 nm, when excitation at 455 nm. The present study was validated according to ICH guidelines and bioanalytical validated according to US-FDA guidance. The fluorescence intensity-concentration plot was linear over the range of 50-1000 ng ml^-1 with limit of detection (LOD) and quantitation (LOQ) of 15.55 and 46.63 ng ml^-1, respectively. The correlation (r) and determination (r²) coefficient was 0.9998 and 0.9997, respectively. Due to high sensitivity and selectivity of the proposed method, it is successfully used for analysis of empagliflozin in its dosage form and human plasma with good recoveries of 98.89% and 98.70%, respectively, without any interfering from matrix components. The corresponding regression equation, Y = 0.756X + 141.93, (r² = 0.9994) for spiked plasma sample. Two level full factorial designs were used to study different experimental parameters that affect the reaction product and to get the optimum method conditions. The suggested method can be used in quality control lab as well as in pharmacokinetic studies of empagliflozin.

Micellar-based spectrofluorimetric method for the selective determination of ledipasvir in the presence of sofosbuvir: application to dosage forms and human plasma

A fast, low-cost, sensitive, and selective spectrofluorimetric method for the determination of ledipasvir was developed and validated. The method is based on an enhancement in the native fluorescence intensity of ledipasvir by 500% of its original value by the formation of hydrogen bonds between the cited drug and Tween-20 in the micellar system (pH = 5.0). All fluorescence measurements were carried out at 425 nm and 340 nm for emission and excitation wavelengths, respectively. A linear relationship between the concentration of ledipasvir and the observed fluorescence intensity was achieved in the range of 0.1-2.0 μg ml^-1 with 0.028, 0.084 μg ml^-1 , for detection and quantitation limits, respectively. The acquired selectivity and sensitivity using the proposed method facilitate the analysis of ledipasvir in spiked human plasma with sufficient percentage recovery (95.36-99.30%). The proposed method was developed and validated according to International Council for Harmonisation (ICH) guidelines. Moreover, the cited drug was successfully determined in its pharmaceutical dosage form using the proposed method. In addition, the validity of the proposed results was statistically confirmed using Student's t-test, variance ratio F-test, and interval hypothesis test.

A simple and rapid spectrofluorometric determination of pomalidomide in spiked plasma and urine. Application to degradation studies

A rapid and accurate spectrofluorimetric method for the determination of pomalidomide was developed and validated based on the measurement of its native fluorescence without the need for any derivatization and separation for the first time. The fluorescence intensity of the drug in acetonitrile solution allowed precise detection at 460 nm after excitation at 296 nm. The calibration curve was linear in the concentration range 31.0-500.0 ng/ml. Limit of detection and limit of quantification were found to be 8.04 and 24.36 ng/ml, respectively. Sensitive results allowed the drug to be detected with good recovery (75.46-109.72%) in human plasma and urine using the developed method. The proposed method was validated in terms of linearity, sensitivity, precision, accuracy, recovery, and stability parameters. Pomalidomide was subjected to degradation under various stress conditions (hydrolytic, oxidative and thermal) to demonstrate that the method was stable, indicating and identifying possible degradation products. In addition, the drug was exposed to electrochemical degradation using the chronoamperometry technique for the first time. Characterization of pomalidomide degradation products obtained because of oxidative degradation and electrochemical degradation was carried out using attenuated total reflection Fourier transform infrared spectroscopy, mass spectrometry and high performance liquid chromatography - mass spectrometry methods and possible structures were proposed.

Micellar spectrofluorimetric protocol for the innovative determination of HCV antiviral (daclatasvir) with enhanced sensitivity: Application to human plasma and stability study

Daclatasvir dihydrochloride (DAC) is a new, direct-acting antiviral drug with powerful inhibitory effect against all hepatitis C virus (HCV) genotypes. A sensitive, simple, fast and specific fluorometric method for estimation of DAC in the presence of sofosbuvir was developed and validated. The method is based on reinforcement the fluorescence intensity of DAC by 170% of its original value in an aqueous solution of hexadecyl trimethyl ammonium bromide (pH 5.5, Teorell and Stenhagen buffer). The fluorescence intensity measurements were accomplished at 387 nm with 328 nm for excitation wavelength. A linear relationship was achieved between the DAC concentration and the fluorescence intensity in a range of 50.0-2000.0 ng ml^-1 with 0.9998 and 0.9999 for the determination and correlation coefficients, respectively. The detection and quantitation limits were 13.4, 40.8 ng ml^-1, respectively. The excellent sensitivity and specificity of the proposed method allowed the efficient estimation of DAC in real human plasma with adequate recovery (81.78 ± 1.57), and the selective determination for DAC in its commercial dosage form without interference from tablet excipient. Moreover, the proposed method was expanded to examine the stability of DAC by determination the parent drug of DAC in the presence of its oxidative, alkaline, acidic, UV, daylight and sunlight degradations products in agreement with ICH guidelines. Furthermore, the kinetic study of acidic and oxidative degradations of DAC was inspected. In addition, the half-life times of the reaction (t_1/2) and the first-order reaction rate constants were estimated. Moreover, a suggestion for the degradation pathway was supposed.

Novel spectrofluorimetric approach for determination of ledipasvir through UV-irradiation: application to biological fluids, pharmacokinetic study and content uniformity test

A highly sensitive and specific fluorescence dependent approach was created for quantitation of a recently approved anti-HCV drug (ledipasvir). This approach relies on the innovative enhancement in fluorescence intensity of ledipasvir upon exposing the cited drug to direct UV irradiation as a photo-physical fluorescence enhancer. The fluorescence of the resultant solution was measured at an emission peak of 375 nm (321 nm excitation). The photoluminescence properties of the resultant product were carefully examined and the quantitative rectilinear concentration plot for the method was 5.0–150.0 ng mL⁻¹ with a detection limit of 0.9 ng mL⁻¹ and a quantitation limit of 2.7 ng mL⁻¹. The excellent analytical features of the proposed method allow to the specific and sensitive estimation of ledipasvir either in plasma samples or in tablet dosage form without any interference from pharmaceutical excipients or other co-formulated anti-HCV drugs (sofosbuvir). The developed analytical and bio-analytical procedures were created and validated according to ICH guidelines and FDA guidelines, respectively. Since the main elimination route for ledipasvir is via faecal excretion, the studied drug was determined for the first time in faecal samples by the method with adequate recovery. Moreover, the pharmacokinetic parameters (C_max, t_max, t_1/2, AUC_0–t, and AUC_0–∞) for ledipasvir were determined by the proposed method. Additionally, the proposed method was successfully applied for supervising the content uniformity for ledipasvir in its pharmaceutical tablets.

Enhancement in the fluorescence spectra of ledipasvir after exposing to strong UV irradiation.

Specific stability indicating spectrofluorimetric method for determination of ledipasvir in the presence of its confirmed degradation products; application in human plasma

A rapid and specific spectrofluorimetric method with higher sensitivity was developed for determination of ledipasvir (LDS) in tablets and human plasma. The proposed method relies on hydrogen bonding formations between the hydroxyl groups of polyoxyethylene 50 stearate and LDS, causing significant enhancement of its native fluorescence. The fluorescence intensity was measured at 430 nm after excitation at 340 nm. The fluorescence-concentration plot was rectilinear over the range 1-400 ng mL^-1 with detection and quantification limits of 0.25 and 1.10 ng mL^-1, respectively. The high sensitivity of the proposed method permits its application for ledipasvir determinations in real human plasma even in the presence of co-administered drugs sofosbuvir and ribavirin. Moreover, the proposed method was further extended to stability studies of ledipasvir after exposure to different forced degradation conditions according to ICH guidelines, along with the structural elucidation of its degradation products utilizing IR and Mass spectra. A proposal for the degradation pathways was presented.

Study on fluorescence properties of HCV antiviral (velpatasvir) and its fluorimetric determination in presence of sofosbuvir; application to stability study and human plasma

Velpatasvir (VLP) is a new, oral, direct-acting antiviral with potent inhibitory activity against all hepatitis C virus (HCV) genotypes. A highly sensitive, simple, fast and specific one fluorometric method for determination of VLP in the presence of sofosbuvir was developed and validated. The fluorescence behavior of VLP in different organic solvents was examined and explained. Methanol was concluded to be the best sensitizing reagent. The native fluorescence intensity of VLP was accomplished at 383 nm with 339 nm for excitation wavelength. The impacts of experimental variables included pH, various organized media, and time of stability were examined and optimized. A linear relationship was achieved between the VLP concentration and the fluorescence intensity in a range of 5 to 5 × 10³ ng mL^-1 with 0.70 and 0.23 ng mL^-1 , for quantitation and detection limits respectively. The proposed method was utilized for analyzing of VLP in human plasma and additionally expanded to examine the stability of VLP after its exposure to various stress conditions, like oxidative, alkaline, acidic, UV, daylight and sunlight conditions, according to ICH guidelines. Furthermore, the kinetics of acidic and oxidative degradations of VLP was examined. Moreover, the half-life times of the reaction (t_1/2 ) and the first-order reaction rate constants were estimated. Finally, a suggestion for the degradation pathway was presented.

Analysis of quetiapine in human plasma using fluorescence spectroscopy

A simple and sensitive spectrofluorimetric method has been development for the assurance of quetiapine fumarate (QTF). The proposed method was utilized for measuring the fluorescence intensity of the yellow fluorescent product at 510nm (λ_ex 470nm). The fluorescent product has resulted from the nucleophilic substitution reaction of QTF with 4-chloro-7-nitrobenzofurazane (NBD-Cl) in Mcllvaine buffer (pH7.0). The diverse variables influencing the development of the reaction product were deliberately changed and optimized. The linear concentration range of the proposed method was of 0.2-2.0μgml^-1.The limits of detection and quantitation were 0.05 and 0.17μgml^-1, respectively. The proposed method was applied for the assurance of QTF in its tablets without interference from basic excipients. In addition, the proposed method was used for in vitro analysis of the QTF in spiked human plasma, the percent mean recovery was (n=3) 98.82±1.484%.

Utility of the chromogenic and fluorogenic properties of benzofurazan for the assay of milnacipran in human urine and plasma

Our article presents the development and validation of two simple, very sensitive, and low-cost spectroscopic methods for the assay of milnacipran hydrochloride in bulk form, pharmaceutical tablets and spiked human urine and plasma. Spectroscopic methods (spectrophotometric and spectrofluorimetric techniques) were dependent on the chromogenic and fluorogenic properties of the 4-chloro-7 nitrobenzofurazan (NBD-Cl) reagent. The reaction product, resulting from the interaction between NBD-Cl and milnacipran in the presence of borate buffer pH 8.5, was measured spectrophotometrically at 465 nm and spectrofluorimetrically at 510 nm after excitation at 465 nm. The absorbance–concentration plot was rectilinear over the range of 1.5–12 μg mL⁻¹ with a limit of quantitation 1.09 μg mL⁻¹, while the fluorescence–concentration plot was rectilinear over the range of 0.03–0.5 μg mL⁻¹ with a limit of quantitation 0.02 μg mL⁻¹. Influential parameters affecting the development and stability of the reaction product were studied and optimized. Assurance of the cited drug in its tablets by our proposed methods was successfully completed without obstruction from the presence of the basic excipients with average percentage recoveries of 99.27 ± 1.18 and 99.44 ± 0.69 for the spectrophotometric and spectrofluorimetric methods, respectively. The spectrofluorimetric method was additionally adopted as a preliminary in vitro study for the assay of the cited drug in spiked human urine and plasma with average percentage recoveries of 101.52 ± 1.01 and 100.38 ± 1.57 for spiked urine and plasma, respectively.

Our article presents the development and validation of two simple, very sensitive, and low-cost spectroscopic methods for the assay of milnacipran hydrochloride in bulk form, pharmaceutical tablets and spiked human urine and plasma.