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

In the current proposed analysis, a new, feasible, and selective fluorimetric approach was designed for baclofen assay. Baclofen is a medication prescribed as a therapy for muscle spasticity that originated from multiple sclerosis or a spinal cord injury, and other cases such as hiccups. The analytical approach relies on the use of ninhydrin to form a fluorescent derivative that was monitored at λex 386 nm or λem 480 nm. Under suitable reaction conditions, the primary amino moiety in baclofen was condensed with ninhydrin and phenylacetaldehyde in the presence of Teorel buffer as a buffered medium. The method exhibited linearity when baclofen concentration was plotted against response in the range 1–10 μg ml−1. Adjustment of the reaction variables and study of validation parameters according to ICH directives were performed correctly. An interference study was implemented to ensure that no discrepancy from the excipient had occurred. Finally, the proposed method was applied successfully for baclofen assay in dosage form and extended to test Mylobac content uniformity. [ABSTRACT FROM AUTHOR]

In this study, spectrofluorimetric and resonance Rayleigh scattering techniques were applied for the first time for determination of rupatadine through two validated methods. The proposed methods were based on a facile association complex formation between rupatadine and erythrosin B reagent in acidic medium. Spectrofluorimetric determination relied on the quenching effect of rupatadine on the fluorescence intensity of erythrosin B at 556 nm (excitation = 530 nm). Conversely, the resonance Rayleigh scattering (RRS) method relied on enhancement in the resonance Rayleigh scattering spectrum of erythrosin B at 344 nm after the addition of rupatadine. The developed methods produced linear results over ranges 0.15−2.0 μg/ml and 0.1−1.5 μg/ml, with detection limits of 0.030 μg/ml and 0.018 μg/ml for the spectrofluorimetric method and the RRS method, respectively. All reaction conditions for rupatadine–erythrosin B formation were optimized experimentally and both methods were validated according to International Council for Harmonisation guidelines. The developed methods were applied to estimate rupatadine content in its pharmaceutical tablet dosage form with acceptable recoveries. Furthermore, a content uniformity test for the commercial rupatadine tablets was successfully applied by the suggested spectroscopic methods according to United States Pharmacopeia guidelines. [ABSTRACT FROM AUTHOR]

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 (λex 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. [ABSTRACT FROM AUTHOR]

A new fluorimetric procedure is described for analysis of milnacipran in its bulk, tablet dosage forms, as well as in biological human samples such as plasma and urine. The suggested method relies on the construction of a derivative with strong fluorescence called dihydropyridine derivative. This derivative resulted from the interaction of the primary amino group in the studied drug and acetylacetone/formaldehyde in McIlvaine buffer (pH 5). The fluorescent dihydropyridine derivative was measured at 470 nm. Influences of experimental variables namely pH, reagent concentration and temperature were examined and optimized. The calibration curve showed linearity over the range of 0.15–1.25 μg ml−1 of milnacipran with an R2 value of 0.9998. The detection limit was 0.02 μg ml−1 and the determination limit was 0.07 μg ml−1. The developed procedure was successfully used in the assay of the studied drug in Avermilan® tablets with excellent selectivity. In addition, the reaction was applied to estimate the drug in spiked human plasma and urine with mean percentage recoveries of 100.04 ± 1.61 and 99.78 ± 0.81% for urine and plasma, respectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Simeprevir (SPV) is a powerful antihepatitis C virus agent that was newly introduced into the pharmaceutical market. We here established and validated an easy, simple, and sensitive spectrofluorimetric method for its estimation at λem 427 nm (λex 337 nm). The suggested procedure was based on two times enhancement in the original emission of SPV through modifying its microenvironment in buffered aqueous solution by adding Triton X‐100. The relationship between the concentration of SPV and the observed fluorescence intensity was linear in the range 0.06–1.0 μg ml−1 with a correlation coefficient of 0.9997. The limits of detection and quantitation were 21 and 64 ng ml−1, respectively. The present method was effectively applied to quantify SPV content in pharmaceutical tablets and human plasma spiked with the drug with no interference from tablet excipients or plasma components. [ABSTRACT FROM AUTHOR]

Mechanism of the enhancement of tolterodine native fluorescence upon inclusion in the SDS micelle aggregate. [Display omitted] • A new, environmentally friendly spectrofluorimetric technique was developed to quantify tolterodine. • The method involves amplifying the drug's native fluorescence by an impressive 720 %, using an aqueous SDS solution. • The developed approach proved highly effective in analyzing tablets as well as assessing tablets content uniformity. • Thanks to its high sensitivity, the proposed method was successfully applied to quantify the drug in spiked human plasma. • Compared with previous methods, the proposed approach offers high simplicity, sensitivity, eco-friendliness and versatility. Tolterodine tartrate (TTD) was the first antimuscarinic medication developed exclusively for the treatment of overactive bladder syndrome and was approved by the FDA in 1998. As a result of the drug's extensive utilization within the local community following its authorization, there is a pressing need to develop and validate a spectrofluorometric method that is economically efficient, easily reproducible, environmentally sustainable, and possesses high sensitivity. The developed approach relies on enhancing the fluorescence intensity of TTD to reach a level 720 % higher than its initial value, achieved through the application of an aqueous sodium dodecyl sulfate (SDS) solution. A strong correlation was observed with a correlation coefficient of 0.9998 between the concentration of TTD and the fluorescence intensity within the range of 25.0–500.0 ng mL−1. This approach could be employed to quantify TTD in its pure form and to examine pharmaceutical tablets for the purposes of verifying uniform content. Additionally, it was utilized for the evaluation of TTD concentrations in spiked human plasma. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of unique, fast, simple, accurate and precise spectroflurimetric method for determination of Octreotide. • Condensation of ninhydrin with octreotide in presence of phenylacetaldehyde gives highly fluorescent product. • Application of the proposed method on pharmaceutical dosage form. A unique spectrofluorimetric protocol has been conceived for octreotide (a synthetic peptide drug) quantitation in both its authentic form and its application to dosage form. The protocol has been established simply upon condensation of octreotide by ninhydrin / phenyl acetaldehyde reagent in buffered media (pH 6.2). An intense fluorescence product has been formed and quantified at 463 nm (390 nm for excitation). After optimization for various experimental conditions, a wide linear interval (0.2–4.0 µg/ml) has been used to construct the calibration curve with a determination coefficient (r2) of 0.9994, a slope ± SD of 81.147 ± 0.7985, and a highly sensitive detection and quantitation limits nearly equal to 0.066 and 0.2 µg/ml, respectively. A proposed protocol has been checked in accordance with ICH validation guidelines, which indicate good accuracy and high precision of the proposed method. Furthermore, this protocol could be perfectly applied for the quantitative estimation of octreotide in its ampoules with a high degree of accuracy and precision. As a result, a developed protocol is ideally appropriate for fast and simple octreotide quantitative estimation in quality control laboratories. [ABSTRACT FROM AUTHOR]

• The influence of photo-induced electron transfer phenomenon on the fluorescence behavior of lurasidone investigation, • The PET process was employed for the determination ionization constant (pka) of the drug using fluorometric titration. • In addition, a highly sensitive spectrofluorimetric method was established and employed for the determination of the drug. • Moreover, spiked human plasma and the content uniformity of commercial tablets were examined using the developed method. • Finally, the greenness of the employed procedure was evaluated and found to be highly green. Photo-induced electron transfer (PET) is one of the most common intermolecular causes that could be responsible for the fluorescence quenching of several fluorophores. Lurasidone is one of these compounds which intrinsic fluorescence could be turned OFF" in alkaline medium because of the PET effect of the amino group of the piperazine ring. Upon protonation of the piperazine nitrogen atom, its electron lone pair was removed, and hence the fluorescence could be recovered, and the fluorescence is turn ON. Accordingly, a new, simple, environmentally friendly, and selective approach with high sensitivity was developed for quantitation of Lurasidone hydrochloride. The technique relies on measuring the strong native fluorescence of the drug in aqueous solution, which was excited at 316 nm and emitted at 398 nm. Lower detection and quantification limits of 12.9 and 39.0 ng mL−1 were achieved. The fluorescence concentration plot was rectilinear in the range of 30–1600 ng mL−1 with a correlation coefficient of 0.9998. The drug concentrations in commercial tablets and spiked plasma were estimated using the indicated method. The suggested approach was also used to assess how closely commercial tablets complied with USP requirements for content uniformity. [ABSTRACT FROM AUTHOR]

Turn ON/OFF of the fluorescence of brexpiprazole based on intermolecular photoinduced electron transfer process. [Display omitted] • Herrin, the first spectrofluorimetric method for Brexpiprazole determination was reported based on a very simple procedure. • The procedure does not include lengthy stages for sample preparation, extraction or chemical derivatization. • The simplicity of method allowed its employment in content uniformity test of commercial tablets. • Thanks to the method's high sensitivity, it was also able to detect the drug in human plasma. • Moreover, the greenness of the procedure was evaluated with metric tools. Brexpiprazole (BRX) is a new antipsychotic drug that recently was used in the treatment of schizophrenia and other psychosis. The presence of benzothiophene ring in its chemical structure makes BRX naturally fluoresces. However, the native fluorescence of the drug was low in neutral or alkaline medium owing to the occurrence of photoinduced electron transfer (PET) from the nitrogen of the piperazine ring to the benzothiophene ring. Protonation of this nitrogen atom using sulfuric acid could efficiently block PET process and thus retaining the strong fluorescence of the compound. Accordingly, a straightforward, highly sensitive, fast and green spectrofluorimetric approach was established for BRX determination. In 1.0 M sulfuric acid solution, BRX exhibited significant native fluorescence measured at emission wavelength of 390 nm after excitation at 333 nm. ICH requirements were used to evaluate the method. The fluorescence intensity and BRX concentration were found to be correlated linearly within the range of 5–220 ng mL−1 with a coefficient of correlation 0.9999. The limit of quantitation was 2.38 ng mL−1 while limit of detection was 0.78 ng mL−1. The developed approach was successfully used to analyze BRX in biological fluids and pharmaceutical dosage form. The suggested approach worked well when applied for testing the uniformity of content. [ABSTRACT FROM AUTHOR]

[Display omitted] • This article represents an overview of the use of resonance Rayleigh scattering in pharmaceutical analysis. • The RRS sensing approaches and the utilized probes were deeply discussed. • In addition, the use of RRS as a detecting system in flow systems (HPLC and flow injection) was illustrated. • The role for nanopaticles on RRS sensing was discussed based on the reported data obtained from SEM, TEM and AFM. • The future challenges for the utility of resonance Rayleigh scattering as a analytical tool are discussed. The present article summarizes the use of resonance Rayleigh scattering (RRS) as a versatile tool in pharmaceutical analysis. RRS was applied for the determination of about 110 pharmaceutical compounds belonging to more than 12 therapeutical groups. The analyte plays an essential role in affecting the RRS signal through different approaches. Ion associate complex formation was the most commonly applied approach. The ability of the analyte to induce aggregation of certain nanoparticles was another approach. Few methods were based on the role of the analyte on the formation of the nanoparticles, in addition to a minor approach relied on RRS quenching. The widely used RRS probes were organic dyes, while neutralization indictors, surfactants, nanoparticles, and inorganic compounds were also utilized. In all approaches, there were evidence for the role of nanostructure in the occurrence of RRS. In addition to the direct RRS measurements, RRS was coupled with HPLC or flow injection as a detection system. [ABSTRACT FROM AUTHOR]