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A novel, simple and sensitive spectrofluorimetric approach for determination of terbutaline sulphate (TER) and its prodrug bambuterol (BAM) in their pure and pharmaceutical dosage forms was developed. The suggested approach depends on enhancing the native fluorescence of either TER or BAM at 315 and 297.2 nm after excitation at 277 and 259 nm, respectively, using sodium dodecyl sulphate (SDS) as a micellar medium. In the presence of 0.7% w/v SDS, ~1.38-fold and 1.18-fold enhancement is achieved in the relative fluorescence intensity (RFI) of TER and BAM, respectively. The fluorescence-concentration curves were rectilinear over the concentration range 0.8-16 μg ml

A new sensitive and instantaneous spectrofluorimetric method for efficient determination of lomefloxacin (LMX) in its pure, dosage form and human plasma was designed. The developed method depends on formation of a metal-chelation compound of LMX as a ligand with zinc(II) in a buffer of acetate (pH 5.5). The following parameters; type of metal, concentration of metal, pH, type of buffer and diluting solvent were optimized. After carefully investigation; 0.2 mM zinc, 2.0 ml acetate buffer (pH 5.5) and water as diluting solvent were set as optimum reaction conditions. Under these conditions, a large increase in the intensity of the fluorescence of LMX was attained at 450 after excitation at 284 nm. The limits of detection and quantification were 5.8 and 1.9 ng ml-1 , respectively, with linearity range of 10.0 to 500.0 ng ml-1 . The binding mode of LMX and zinc(II) ion (Zn2+ ) was found to be 2:1, respectively, and confirmed by Job's plot method. Furthermore, it extended to the analysis of LMX in the spiked plasma of humans with percentage recovery (98.70 ± 0.97 to 100.30 ± 1.69%, n = 3).

A new, accurate, nonextractive, and sensitive fluorimetric approach was proposed and validated for the first time estimation of colistin sulfate and its inactive prodrug colistimethate sodium in its bulk form, pharmaceutical formulations, and human plasma. The approach relied on condensation between acetylacetone/formaldehyde and the primary amino moiety of nonfluorescent colistin in Teorell and Stenhagen buffer (pH 2.8) by the Hantzsch reaction to form a highly fluorescent dihydropyridine derivative. The fluorescent product was measured at 460 nm (λex = 402 nm). A plot of relative fluorescence intensity (RFI) versus concentration was rectilinear over the range 200-4000 ng ml-1 with excellent correlation (r) and determination (r2 ) coefficients of 0.9999 and 0.9998, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 40.91 and 123.99 ng ml-1 , respectively. The present procedure was useful for determination of colistin sulfate either in powder form for suspension or in its parenteral prodrug colistimethate sodium in vial formulation. The investigated approach was applied for in vitro quantification of this drug in spiked human plasma, with a per cent mean recovery of 98.24 ± 1.34. The proposed method is reliable, selective, and does not require tedious sample pretreatment steps, expensive instrumentation, or harmful reagents, all of which make it ideally suited for use in quality control laboratories.

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.

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.

A validated straightforward and sensitive spectrofluorimetric procedure was developed to assay trifluoperazine hydrochloride, promethazine hydrochloride, and perazine maleate. The procedure was dependent on oxidation of the investigated phenothiazines using a known excess of ammonium cerium sulfate as oxidizing agent and overseeing the fluorescence intensity of the resultant Ce3+ ion as the product of this reaction at λcx = 254 nm. and λem = 355 nm. Various parameters controlling the reaction were investigated and optimized. Linear calibration graphs were found in the general concentration range 5-30 ng/ml with a general correlation coefficient range 0.9994-0.9995. Limits of detection were 0.97, 0.70 and 0.56 ng/ml, whereas limits of quantification were 3.24, 2.12 and 1.89 ng/ml for trifluoperazine hydrochloride, promethazine hydrochloride and perazine maleate, respectively. The procedure was implemented successfully for analyses of the cited drugs in their trade dosage preparations such as tablets and syrups. The effect of possible interference from common excipients and their sulfoxide oxidized product was studied and the procedure showed good recovery of the drugs under study in their available dosage preparations. The possible effect of structure variation of the studied drugs on the experimental conditions and sensitivity observed with each one was also discussed.

A sensitive, simple, accurate and less expensive fluorimetric method was designed and validated for analysis of heptaminol HCl in both its pure and dosage forms, as well as in human plasma. The main principle used in the proposed approach was the condensation reaction between heptaminol's primary amino moiety and ethyl acetoacetate/formaldehyde reagents, giving a derivative that was highly fluorescent at 416 nm after excitation at 350 nm. Various experimental parameters that affected either the product's development or its stability were evaluated and optimized. The constructed calibration curve was linear over the range 0.2-2 μg/ml, with a good correlation coefficient (0.9996). Both the calculated limit of detection and limit of quantitation were 0.06 and 0.18 μg/ml, respectively. The presented approach was a success when used to determine Corasore® tablets and was validated according to International Council for Harmonisation guidelines.

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 highly accurate, simple and sensitive spectrofluorimetric analytical method for dapagliflozin (DGF) quantitation was developed. The proposed method was successively applied to DGF analysis in both its pure and pharmaceutical dosage forms. This method was developed to investigate DGF stability in its degradation products, as laid out in International Council for Harmonisation (ICH) rules. Kinetics of alkaline degradation of DGF was also calculated. The half-life time (t1/2 ) of the reaction was 75.32 min. An alkaline degradation pathway was described. The present study involved measurement of the second-derivative synchronous fluorescence intensity of DGF at Δλ = 30 nm. Peak amplitude was measured at 322 nm. Linear range of the calibration curve was 0.1-1.0 μg ml-1 . Lower detection and quantitation limits were 0.023 and 0.071 μg ml-1 , respectively, and indicated good sensitivity of the proposed method. Mean per cent recovery was 99.78 ± 1.78%. The proposed analytical approach was successfully applied to DGF in the quality control laboratory and would be suitable as a stability-indicating assay.

A new validated spectrofluorimetric method was proposed for dapagliflozin (DGF) analysis in bulk, plexin its commercially available tablets and in spiked human plasma. The proposed spectrofluorimetric method depended on the formation of a fluorescent complex soluble in organic liquids by a substitution reaction between 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) reagent and DGF in aqueous buffered solution at pH 7. The fluorescence intensity was measured at 522 nm after excitation at 453 nm. The high selectivity of the proposed method allowed analysis of DGF in dosage form and human plasma samples with average recovery values of 99.84 ± 1.38% and 98.71 ± 1.80%, respectively, without any interference from matrix components. The calibration range was 50-1000 ng ml-1 . The limit of detection (LOD) and limit of quantitation (LOQ) were 14.24 ng ml-1 and 43.14 ng ml-1 , respectively. The estimated relative standard deviation values were lower than 2.0%, this showed the excellent precision at both levels. Factorial design was used to get the optimum method conditions for the analysis of the resulting DGF fluorescence complex in different matrices. The proposed method could be used in routine analysis of DGF in quality control laboratories. Also, it could be used to assay DGF in human plasma and be applied for pharmacokinetic investigation of DGF.