Derivative emission spectrofluorimetry for the simultaneous determination of guaifenesin and phenylephrine hydrochloride in pharmaceutical tablets

Rapid, simple and sensitive derivative emission spectrofluorimetric methods have been developed for the simultaneous analysis of binary mixtures of guaifenesin (GUA) and phenylephrine hydrochloride (PHE). The methods are based upon measurement of the native fluorescence intensity of the two drugs at λ_ex = 275 nm in methanolic solutions, followed by differentiation using first (D1) and second (D2) derivative techniques. The derivative fluorescence intensity–concentration plots were rectilinear over a range of 0.1–2 µg/mL for both GUA and PHE. The limits of detection were 0.027 (D1, GUA), 0.025 (D2, GUA), 0.031 (D1, PHE) and 0.033 (D2, PHE) µg/mL and limits of quantitation were 0.089 (D1, GUA), 0.083 (D2, GUA), 0.095 (D1, PHE) and 0.097 (D2, PHE) µg/mL. The proposed derivative emission spectrofluorimetric methods (D1 and D2) were successfully applied for the determination of the two compounds in binary mixtures and tablets with high precision and accuracy. The proposed methods were fully validated as per ICH guidelines. Copyright © 2014 John Wiley & Sons, Ltd.     

Micellar-emphasized simultaneous determination of ivabradine hydrochloride and felodipine using synchronous spectrofluorimetry

A sensitive and green micellar spectrofluorimetric approach was applied for the simultaneous estimation of ivabradine hydrochloride (IVB) and felodipine (FLD) in the ng/ml concentration range. The approach depended on measuring the first derivative synchronous peak amplitude (¹D) of both drugs at ∆λ = 60 nm in a Tween-80 micellar system. The method was rectilinear alongside the concentration ranges 0.02–0.4 μg/ml and 0.05–1.0 μg/ml at 269.5 nm and 378.5 nm for IVB and FLD, respectively. The proposed method was validated by following the International Council for Harmonization guidelines. The method was successfully applied without interference for laboratory-prepared synthetic mixtures, single pharmaceutical preparations, and within spiked biological fluids with acceptable percentage recoveries. A comparison of the performance of the suggested method with other methods, showed no discrepancy. The method’s ecofriendly property evaluated using three different tools, confirming an excellent green method.     

Spectrofluorimetric determination of acotiamide hydrochloride trihydrate in the presence of its oxidative degradation product

Acotiamide hydrochloride trihydrate is a novel gastroprokinetic drug which has been recently approved for the treatment of patients with functional dyspepsia. This study presents the first reported to investigate the fluorimetric behavior of acotiamide hydrochloride trihydrate in the presence of its oxidative degradation product. All variables that affect fluorescence intensity were studied and optimized. The described method involved the measurement of native fluorescence of the drug in ethanol at 404 nm after excitation at 326 nm. Calibration plot was found to be linear over the concentration range 0.1–0.9 μg/ml. The specificity of the method has been tested via selective determination of the studied drug in its synthetic mixtures with its degradation product. The proposed method has been successfully applied to the analysis of the drug in its new pharmaceutical dosage form and the results have been statistically compared with the reported HPLC method showing no significant differences by applying t‐test and F‐test.     

Online naphazoline quality control by micellar‐enhanced spectrofluorimetry

The aim of this study was to develop a method for online spectrofluorimetric quality control of naphazoline (NPZ) in pharmaceuticals and raw drugs. A combination of a flow‐injection analysis (FIA) system with micellar‐enhanced fluorescence detection is presented as a powerful alternative for the rapid and sensitive analysis of naphazoline. Since NPZ shows low native fluorescence, the use of an anionic surfactant, such as sodium dodecyl sulphate (SDS), provides a considerable enhancement of fluorescence intensity and the nature of the technique allows a possible and easy adaptation to a FIA system. Using λ_exc = 280 nm and λ_em = 326 nm, a good linear relationship (LOL) was obtained in the range 0.003–10 µg mL^?1 with a detection limit (LOD) of 3 × 10^?4 µg mL^?1 (s/n = 3). Parameters related to the nature of the analytical signal and to the FIA manifold were optimized. Satisfactory recoveries were obtained in the analysis of commercial pharmaceutical formulations. The proposed method is simple, accurate and allows for high‐speed sampling and considerably shorter analysis times. In addition, it requires inexpensive equipment and reagents and has easy operational conditions and no side effects, thus avoiding environmental pollution through toxic waste. Copyright © 2011 John Wiley & Sons, Ltd.     

盐酸司来吉兰中右旋异构体含量的HPLC分析

采用高效液相色谱法分离和检测盐酸司来吉兰的光学异构体。对影响分离和检测的色谱柱、流动相、检测波长和样品的配制方法等进行了筛选,并对建立的方法进行了线性、精密度、回收率、最小检出量和溶液的稳定性研究。结果表明在v(环已烷)∶v(异丙醇)为99.8∶0.2,流速1 mL.min-1,柱温10~30℃条件下,盐酸司来吉兰的光学异构体得到了基线分离,所建立的自身对照方法能有效的测定出盐酸司来吉兰中右旋异构体的含量。     

A novel spectrofluorimetric method for the assay of pseudoephedrine hydrochloride in pharmaceutical formulations via derivatization with 4-chloro-7-nitrobenzofurazan

A new highly sensitive and specific spectrofluorimetric method has been developed to determine a sympathomimetic drug pseudoephedrine hydrochloride. The present method was based on derivatization with 4-chloro-7-nitrobenzofurazan in phosphate buffer at pH 7.8 to produce a highly fluorescent product which was measured at 532 nm (excitation at 475 nm). Under the optimized conditions a linear relationship and good correlation was found between the fluorescence intensity and pseudoephedrine hydrochloride concentration in the range of 0.5-5 μg mL(-1). The proposed method was successfully applied to the assay of pseudoephedrine hydrochloride in commercial pharmaceutical formulations with good accuracy and precision and without interferences from common additives. Statistical comparison of the results with a well-established method showed excellent agreement and proved that there was no significant difference in the accuracy and precision. The stoichiometry of the reaction was determined and the reaction pathway was postulated.     

Studies on the interaction of palmatine hydrochloride with bovine hemoglobin

The interaction between bovine hemoglobin (BHb) and palmatine hydrochloride (PMT) was investigated at different temperatures using multispectroscopy, as well as the effect of common metal ions (Ca²⁺, Mg²⁺, Zn²⁺, Cu²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺) on the BHb–PMT system. Results showed that the quenching mechanism of PMT on BHb was a static process. The electrostatic force played an important role in the conjugation reaction between BHb and PMT. The order of magnitude of the binding constants (K_a) was 10⁴, and the number of binding sites (n) in the binary system was ~ 1. The binding distance (r) was ~ 2.44 nm and the primary binding for PMT was located at β‐37 tryptophan in the hydrophobic cavity of BHb. In addition, the Hill's coefficients were ~ 1. Synchronous and circular dichroism spectra revealed that the microenvironment and the conformation of BHb were changed during the binding reaction. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen bonding-assisted interaction between amitriptyline hydrochloride and hemoglobin: spectroscopic and molecular dynamics studies

Herein, we have explored the interaction between amitriptyline hydrochloride (AMT) and hemoglobin (Hb), using steady-state and time-resolved fluorescence spectroscopy, UV–visible spectroscopy, and circular dichroism spectroscopy, in combination with molecular docking and molecular dynamic (MD) simulation methods. The steady-state fluorescence reveals the static quenching mechanism in the interaction system, which was further confirmed by UV–visible and time-resolved fluorescence spectroscopy. The binding constant, number of binding sites, and thermodynamic parameters viz. ΔG, ΔH, ΔS are also considered; result confirms that the binding of the AMT with Hb is a spontaneous process, involving hydrogen bonding and van der Waals interactions with a single binding site, as also confirmed by molecular docking study. Synchronous fluorescence, CD data, and MD simulation results contribute toward understanding the effect of AMT on Hb to interpret the conformational change in Hb upon binding in aqueous solution.     

Determination of procaine hydrochloride using flow injection inhibitory chemiluminescence

A new flow injection chemiluminescent method has been developed for the determination of procaine hydrochloride, based on the inhibition of the chemiluminescence reaction of luminol–hydrogen peroxide by procaine hydrochloride. The influence of several surfactants and β‐cyclodextrin on the chemiluminescence intensity were studied. It was found that β‐cyclodextrin enhanced the decrease in chemiluminescence intensity. The method is simple, convenient and sensitive, with a detection limit (3 σ) of 0.08 µg/mL. The decreased chemiluminescence intensity is linear, with the concentration of procaine hydrochloride in the range 0.2–100.0 µg/mL and 100.0–400.0 µg/mL. The relative standard deviation for 10 repeated measurements were 4.5% and 3.4% for 1.0 and 20.0 µg/mL procaine hydrochloride, respectively. The method has been successfully applied to the determination of procaine hydrochloride in injection solutions of this drug. Copyright © 2003 John Wiley & Sons, Ltd.     

Biophysical study on the interaction of cartap hydrochloride and hemoglobin: Heme degradation and functional changes of protein

Cartap hydrochloride is a mildly perilous insecticide known as “Padan” which is used largely in agricultural farms to control weevil and caterpillars. The over use of cartap causes harmful effects on human health. Since the blood may acts as a target and carrier for insecticides, the effect of these compounds on blood in mammalian toxicology is very important. Hemoglobin is a tetramer protein that play critical role in oxygen transport. The aim of this study was to analyze and compare the function and structural changes of hemoglobin in the presence of different concentrations of cartap by employing different spectroscopic techniques. The obtained results show that cartap has a high hemolytic effect which is increased with cartap concentration and reduces the thermal midpoint of hemoglobin. Fluorescence measurements reveal heme degradation at different concentrations of cartap. In consequence of theoretical and experimental results, cartap has an undesirable effect on hemoglobin structure and function.     

Enhanced spectrofluorimetric determination of two novel combination therapies for the treatment of benign prostatic hyperplasia containing tamsulosin hydrochloride

Two novel combination therapies for the treatment of benign prostatic hyperplasia were analyzed using simple and enhanced spectrofluorimetric methods based on derivative and derivative ratio techniques. The two combinations contained tamsulosin hydrochloride (TAM) as a minor component with tolterodine tartrate (TOL) or solifenacin succinate (SOL). The fluorescence of the three drugs under study was measured in methanolic water solution. For the TAM and SOL mixture, successful resolution between both drugs was achieved by derivative manipulation of both ratio and zero‐order emission spectra with good linearity in the ranges of 0.75–3.50 and 2.5–15.0 μg ml^?1 for TAM and SOL, respectively. Extensive emission spectral overlap was observed for the TAM and TOL mixture. Therefore, only derivative application of the ratio emission spectra resolved such overlap and quantitated TAM and TOL simultaneously in the ranges 0.75–3.50 and 2.5–20.0 μg ml^–1 for TAM and TOL, respectively. Optimization of various experimental parameters that affected the fluorescence intensity of the three drugs was performed. Successful application of all proposed methods was achieved for analysis of the two drugs in each combination therapy in their laboratory‐prepared mixtures and dosage forms with good accuracy and precision.     

Determination of enantiomeric impurity in besifloxacin hydrochloride by chiral high-performance liquid chromatography with precolumn derivatization

Besifloxacin hydrochloride is a novel chiral broad-spectrum fluoroquinolone developed for the treatment of bacterial conjunctivitis. R-besifloxacin hydrochloride is used in clinics as a consequence of its higher antibacterial activity. To establish an enantiomeric impurity determination method, some chiral stationary phases (CSPs) were screened. Besifloxacin enantiomers can be separated to a certain extent on Chiral CD-Ph (Shiseido Co., Ltd., Japan), Chiral AGP, and Crownpak CR (+) (Daicel Chemical IND., Ltd., Japan). However, the selectivity and sensitivity were both unsatisfactory on these three CSPs. Therefore, Chiral AGP, Chiral CD-Ph, and Crownpak CR (+) were not used in the enantiomeric impurity determination of besifloxacin hydrochloride. The separation of enantiomers of besifloxacin was further performed using a precolumn derivatization chiral high-performance liquid chromatography method. 2,3,4,6-Tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate was used as the derivatization reagent. Besifloxacin enantiomer derivates were well separated on a C(18) column (250 × 4.6 mm, 5 μm) with a mobile phase that consisted of methanol-KH(2)PO(4) buffer solution (20 mM; pH 3.0) (50:50, v/v). Selectivity, sensitivity, linearity, accuracy, precision, stability, and robustness of this method were all satisfied with the method validation requirement. The method was suitable for the quality control of enantiomeric impurity in besifloxacin hydrochloride.     

Enhanced healing of cartilaginous injuries by glucosamine hydrochloride

We investigated the restorative effect of orally administered glucosamine hydrochloride (GlcN) on the experimentally produced cartilaginous injuries in rabbits. A total of three holes in the left stifle joint including one in the medial trochlear ridge and two in the trochlear sulcus (proximal and distal) of articular cartilage were made surgically using a drill. For the control group, only tap water and for the glucosamine group, a water based solution of GlcN (1 g/head) was administered daily, respectively. We observed the clinical symptoms daily and the condition of the injured part was observed visually and histologically at 3 weeks after the operation. There was no difference in body weight or general conditions between the two groups. However, in the control group, the muscle weight of the biceps of the left femur was significantly reduced (p<0.05). With respect to the medial trochlear injury, four out of six cases in the control group and five out of six cases in the glucosamine group were cured, respectively. With respect to the proximal and the distal holes in sulcus, only two out of six cases in the control group and five expansive out of six cases in the glucosamine group were cured. There was significant difference between the glucosamine group and the control with respect to healing of the proximal hole (p<0.05) and the total points (p<0.05), indicating that the artificial cartilage injuries were facilitated by GlcN. On histological examination, the injured parts were covered by fibrous connective tissues in the control, whereas in the glucosamine group, the massive proliferation of matured cartilaginous tissues was observed, and the regenerated cartilaginous tissues were surrounded by the proliferation of chondroblast cells. In the regenerated tissue, matured cartilage substrate was about to be formed. Safranin O and alcian blue stains marked significantly dense in the glucosamine group than in the control (p<0.01) in injured parts as well as in non-injured joint cartilage.     

Derivative emission spectrofluorimetry: Application to the analysis of newly approved FDA combination of ibuprofen and famotidine in tablets

A new combination of ibuprofen (NSAID) and famotidine (H₂ receptor antagonist) was recently approved by the FDA. It was formulated to relief pain while decreasing the risk of ulceration, which is a common problem for patients receiving NSAID. A rapid and simple derivative emission spectrofluorimetric method is proposed for the simultaneous analysis of this combination in their pharmaceutical preparation. The method is based upon measurement of the native fluorescence intensity of the two drugs at λ_ex = 233 nm in acetonitrile. The emission data were differentiated using the first (D1) derivative technique. The plots of derivative fluorescence intensity versus concentration were rectilinear over a range of 2–35 and 0.4–8 µg/mL for both ibuprofen (IBU) and famotidine (FAM), respectively. The method was sensitive as the limits of detection were 0.51 and 0.12 µg/mL and limits of quantitation were 1.70 and 0.39 µg/mL, for IBU and FAM respectively. The proposed derivative emission spectrofluorimetric method was successfully applied for the determination of the two drugs in their synthetic mixtures and tablets with good accuracy and precision. The proposed method was validated as per ICH guidelines. Copyright © 2014 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence method for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride

A sensitive and simple flow‐injection chemiluminescence (FI‐CL) method, which was based on the CL intensity generated from the redoxreaction of potassium permanganate (KMnO₄)–formaldehyde in vitriol (H₂SO₄) medium, has been developed, validated and applied for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride. Besides oxidants and sensitizers, the effect of the concentration of H₂SO₄, KMnO₄ and formaldehyde was investigated. Under the optimum conditions, the linear range was 1.0 × 10^?2–7.0 mg/L for naphazoline hydrochloride and 5.0 × 10^?2–10.0 mg/L for oxymetazoline hydrochloride. During seven repeated inter‐day and intra‐day precision tests of 0.1, 1.0 and 10.0 mg/L samples, the relative standard deviations all corresponded to reference values. The detection limit was 8.69 × 10^?3 mg/L for naphazoline hydrochloride and 3.47 × 10^?2 mg/L for oxymetazoline hydrochloride (signal‐to‐noise ratio ≤3). This method has been successfully implemented for the determination of naphazoline hydrochloride and oxymetazoline hydrochloride in pharmaceuticals. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of propafenone hydrochloride by flow‐injection analysis coupled with resonance light scattering detection

A simple, sensitive and rapid flow injection analysis (FIA) method with resonance light scattering (RLS) was described for the determination of propafenone (PPF). The method was based on the ion‐association reaction of 12‐tungstophosphoric acid (TP) with propafenone. In pH 1.0 acidic medium, TP reacted with PPF to form an ion‐associate complex, which resulted in a significant enhancement of RLS intensity. The maximum scattering peak was located at 340 nm, the RLS intensity was proportional to the concentration of PPF in the range 0.003–9.0 µg/mL, and the detection limit (3σ) of 1.0 ng/mL was obtained at a sampling rate of 60 samples/h. The feasible reaction conditions and FIA parameters for the system were optimized. The method proposed in this paper shows satisfactory reproducibility with a relative standard deviation (RSD) of 2.1% for 10 successive determinations of 2.0 µg/mL PPF. The present method had been successfully applied to the determination of PPF in serum samples and pharmaceutical samples. The results obtained were in agreement with the method used in the Chinese Pharmacopoeia. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of phenformin hydrochloride using molecular imprinting technology coupled with flow-injection chemiluminescence

A novel method was developed using molecular imprinting technology (MIT) coupled with flow‐injection chemiluminescence (FI‐CL) for highly sensitive detection of phenformin hydrochloride (PH). The phenformin imprinted polymer was synthesized with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross‐linker. Newly synthesized molecularly imprinted polymer (MIP) particles were packed into a column as a selective recognition element for determination of PH. A CL method for the determination of PH was developed based on the CL reaction of PH with N‐bromosuccinimide sensitized by eosin Y in basic media. The optimization of detection conditions was investigated. The CL intensity responded linearly to the concentration of PH in the range 0.09–2.0 µg/mL, with a correlation coefficient of 0.9920. The detection limit was 0.031 µg/mL. The relative standard deviation for the determination of 1.0 µg/mL PH solution was 1.0% (n = 11). The method was applied to the determination of PH in urine samples, with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.     

Fourth‐derivative synchronous spectrofluorimetry and HPLC with fluorescence detection as two analytical techniques for the simultaneous determination of itopride and domperidone

Two simple, rapid and sensitive methods, namely, fourth‐derivative synchronous spectrofluorimetry (method I) and HPLC with fluorescence detection (method II) were developed for the simultaneous analysis of a binary mixture of itopride HCl (ITP) and domperidone (DOM) without prior separation. The first method was based on measuring the fourth derivative of the synchronous fluorescence spectra of the two drugs at Δλ = 40 nm in methanol. The different experimental parameters affecting the synchronous fluorescence of the studied drugs were carefully optimized. Chromatographic separation was performed in < 6.0 min using a RP C₁₈ column (250 mm × 4.6 mm i.d., 5 µm particle size) with fluorescence detection at 344 nm after excitation at 285 nm. A mobile phase composed of a mixture of 0.02 M phosphate buffer with acetonitrile in a ratio of 55 : 45, pH 4.5, was used at a flow rate of 1 mL/min. Linearity ranges were found to be 0.1–2 µg/mL for ITP in both methods, whereas those for DOM were found to be 0.08–2 and 0.05–1.5 µg/mL in methods I and II, respectively. The proposed methods were successfully applied for the determination of the studied drugs in synthetic mixtures and laboratory‐prepared tablets. Copyright © 2015 John Wiley & Sons, Ltd.     

Environmentally benign first derivative synchronous spectrofluorimetry for the analysis of two binary mixtures containing duloxetine with avanafil or tadalafil in spiked plasma samples

Antidepressants can cause sexual dysfunction side effects, necessitating the co-administration of phosphodiesterase type 5 inhibitors. The simultaneous determination of these drugs in biological fluids is critical for therapeutic drug monitoring. For the first time, two binary mixtures containing duloxetine with either avanafil or tadalafil were estimated utilizing simple green spectrofluorimetric methods without the need for a previous separation step. The study was based on first derivative synchronous spectrofluorimetry in ethanol using a change in wavelength difference (∆λ) of 20 and 25 nm for the first and second combinations, respectively. Duloxetine and avanafil were estimated at 297.7 and 331 nm in their binary mixture, while duloxetine and tadalafil were determined at 290.3 and 297.7 nm, respectively. The linearity was achieved over the ranges of 0.1–1.5 μg mL⁻¹ for both duloxetine and avanafil and 0.01–0.40 μg mL⁻¹ for tadalafil, with limits of detection of 0.013, 0.022, and 0.004 μg mL⁻¹ for duloxetine, avanafil, and tadalafil, respectively. Successful application of the developed approaches was accomplished for the estimation of the two mixtures in dosage forms as well as human plasma with excellent percentage recoveries (96–103.75% in plasma), which supports their suitability for use in quality control laboratories and pharmacokinetic studies. Moreover, the adopted approaches' greenness was evidenced by applying three tools.     

Determination of metformin hydrochloride using precolumn derivatization with acetaldehyde and capillary electrophoresis coupled with electrochemiluminescence

A novel method was developed using capillary electrophoresis (CE) coupled with tris(2,2′‐bipyridyl)ruthenium(II) electrogenerated chemiluminescence (ECL) for highly sensitive detection of metformin hydrochloride (MH) derivatizatized with acetaldehyde. The precolumn derivatization of MH with acetaldehyde was performed in phosphate buffer solution (0.3 mol/L, pH 7.5) at room temperature for 120 min. The effects of acetaldehyde concentration, buffer pH, electrokinetic voltage and injection time were investigated. Under optimized detection conditions, the MH ECL detection sensitivity was more than 120 times that without derivatization. The linear concentration range for MH was 0.001–15.00 μg/mL (with a correlation coefficient of 0.9992). The detection limit was 0.31 ng/mL with a signal:noise ratio of 3. The recoveries of MH in human urine were in the range 98.50–99.72%. Copyright © 2011 John Wiley & Sons, Ltd.