Spectrophotometric and spectrofluorimetric methods for analysis of acyclovir and acebutolol hydrochloride

Simple and sensitive spectrophotometric and spectrofluorimetric methods are described for analysis of acebutolol hydrochloride. The proposed methods are based on oxidation of the selected drug with cerium(IV) ion in acidic medium with subsequent measurement of either the decrease in absorbance at 320 nm or the fluorescence intensity of the produced cerous(III) ion at 363 nm (excitation at 250 nm). Beer's law obeyed from 1.0-7.0 microg ml(-1) and 0.25-2.5 microg ml(-1) acebutolol hydrochloride, using the spectrophotometric and spectrofluorimetric method, respectively. The proposed methods were successfully applied for determination of the selected drug in its pharmaceutical preparation with good recoveries.     

Spectrophotometric and spectrofluorimetric methods for analysis of tramadol, acebutolol and dothiepin in pharmaceutical preparations

Sensitive spectrophotometric and spectrofluorimetric methods are described for the determination of tramadol, acebutolol and dothiepin (dosulepin) hydrochlorides. The two methods are based on the condensation of the cited drugs with the mixed anhydrides of malonic and acetic acids at 60 degrees C for 25-40 min. The coloured condensation products are suitable for the spectrophotometric and spectrofluorimetric determination at 329-333 and 431-434 nm (excitation at 389 nm), respectively. For the spectrophotometric method, Beer's law was obeyed from 0.5 to 2.5 microg ml(-1) for tramadol, dothiepin and 5-25 microg ml(-1) for acebutolol. Using the spectrofluorimetric method linearity ranged from 0.25 to 1.25 microg ml(-1) for tramadol, dothiepin and 1-5 microg ml(-1) for acebutolol. Mean percentage recoveries for the spectrophotometric method were 99.68+/-1.00, 99.95+/-1.11 and 99.72+/-1.01 for tramadol, acebutolol and dothiepin, respectively and for the spectrofluorimetric method, recoveries were 99.5+/-0.844, 100.32+/-0.969 and 99.82+/-1.15 for the three drugs, respectively. The optimum experimental parameters for the reaction has been studied. The validity of the described procedures was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed methods were successfully applied for the determination of the selected drugs in their pharmaceutical preparations with good recoveries. The procedures were accurate, simple and suitable for quality control application.     

New spectrophotometric and spectrofluorimetric methods for the determination of angiotensin II receptor antagonists in tablets and plasma

Spectrophotometric and spectrofluorimetric methods for the determination of five Angiotensin II type 1 receptor antagonists in tablets and plasma have been developed and optimized. The spectrophotometric method involves the addition of a measured excess of bromate-bromide in HCl medium and subsequent estimation of the residual bromine by reacting with a fixed amount of methyl orange. The spectrofluorimetric method depends on the oxidation of the drugs with cerium(IV) and subsequent monitoring of the fluorescence of the induced cerium(III) at 365 nm with excitation at 255 nm. Both of the proposed methods were successfully applied to the determination of the investigated drugs in their pure forms and pharmaceutical preparations. Besides, the spectrofluorimetric method was applied to the determination of irbesartan and telmisartan in biological fluids with good accuracy and precision.     

Kinetic Spectrophotometric Analysis and Spectrofluorimetric Analysis of Ciprofloxacin Hydrochloride and Norfloxacin in Pharmaceutical Preparations Using 4‐Chloro‐7‐Nitrobenzo‐2‐Oxa‐1,3‐Diazole (NBD‐Cl)

Simple, reliable, sensitive and accurate kinetic spectrophotometric and spectrofluorimetric methods were proposed for the determination of ciprofloxacin hydrochloride (CPX) and norfloxacin (NRX) in pure form and in pharmaceuticals. The methods are based on coupling the studied drugs with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) in the presence of alkaline borate buffer. Spectrophotometric measurement was achieved by recording the absorbance at 477 nm after a fixed time of 20 and 15 min on a water bath adjusted at 70 ± 1 °C for CPX and NRX, respectively. The same product exhibited emission peaks at 540 nm. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The absorbance concentration plots were linear over the ranges 3‐18 and 2.5‐15.0 μg/mL for CPX and NRX, respectively, while the fluorescence concentration plots were linear over the ranges 0.06‐0.36 and 0.05‐0.30 μg/mL for CPX and NRX, respectively. The limit of detection of the kinetic method was about 0.2 μg/mL for both drugs while the fluorescence measurement enabled their detection at a concentration of about 0.012 μg/mL. The proposed methods were successfully applied for the assay of the two drugs in their commercial products. The results obtained were statistically compared with those obtained by reference HPLC and spectrophotometric methods. The stoichiometry of the reaction was determined and the reaction pathway was postulated.     

Highly sensitive and selective spectrophotometric and spectrofluorimetric methods for the determination of ropinirole hydrochloride in tablets

Three sensitive, selective, accurate spectrophotometric and spectrofluorimetric methods have been developed for the determination of ropinirole hydrochloride in tablets. The first method was based on measuring the absorbance of drug solution in methanol at 250 nm. The Beer's law was obeyed in the concentration range 2.5-24 microg ml(-1). The second method was based on the charge transfer reaction of drug, as n-electron donor with 7,7,8,8-tetracyanoquinodimethane (TCNQ), as pi-acceptor in acetonitrile to give radical anions that are measured at 842 nm. The Beer's law was obeyed in the concentration range 0.6-8 microg ml(-1). The third method was based on derivatization reaction with 4-chloro-7-nitrobenzofurazan (NBD-Cl) in borate buffer of pH 8.5 followed by measuring the fluorescence intensity at 525 nm with excitation at 464 nm in chloroform. Beer's law was obeyed in the concentration range 0.01-1.3 microg ml(-1). The derivatization reaction product of drug with NBD-Cl was characterized by IR, 1H NMR and mass spectroscopy. The developed methods were validated. The following analytical parameters were investigated: the molar absorptivity (epsilon), limit of detection (LOD, microg ml(-1)) and limit of quantitation (LOQ, microg ml(-1)), precision, accuracy, recovery, and Sandell's sensitivity. Selectivity was validated by subjecting stock solution of ropinirole to acidic, basic, oxidative, and thermal degradation. No interference was observed from common excipients present in formulations. The proposed methods were successfully applied for determination of drug in tablets. The results of these proposed methods were compared with each other statistically.     

Spectrofluorimetric determination of drugs containing active methylene group using N1-methyl nicotinamide chloride as a fluorigenic agent

A spectrofluorimetric method was described for the determination of drugs containing active methylene groups adjacent to carbonyl groups. The method was applied successfully to the determination of three life saving cardiovascular drugs, with narrow therapeutic indices: pentoxifylline (I), propafenone hydrochloride (II) and acebutolol hydrochloride (III), in laboratory-prepared mixtures, in commercial tablets and in plasma samples. The method involved the reaction of each of the tested drugs with N1-methyl nicotinamide chloride (NMNCl) in the presence of alkali, followed by addition of formic acid, where highly fluorescent reaction products were produced. The produced fluorescence were measured quantitatively at 472 nm (lambdaex 352 nm), 409 nm (lambdaex 310 nm) and 451 nm (lambdaex 266 nm) for (I), (II), and (III) respectively. The method was linear over concentration ranges of 10-1000 microg/ml , 0.2-12 microg/ml and 0.08-10 microg/ml in standard solutions for (I), (II), and (III) respectively. In spiked human plasma samples, calibration graphs were linear over concentration ranges of 20-1000 microg/ml, 0.2-15 microg/ml and 0.08-10 microg/ml for (I), (II), and (III) respectively. The method showed good accuracy, specificity and precision in both laboratory-prepared mixtures and spiked human plasma samples. The proposed method is simple, with low instrumentation requirements, suitable for quality control application, bioavailability and bioequivalency studies.     

Spectrophotometric Determination of Acyclovir and Amantadine Hydrochloride through Metals Complexation1

A simple spectrophotometric method for determination of some antiviral drugs, such as acyclovir and amantadine hydrochloride in pure and dosage forms, have been developed. The proposed method is based on the reactions of the selected drugs and metals. Acyclovir was reacted with copper (II) and cobalt (II) using a borax/sodium pH 9 hydroxide buffer, and in a non-aqueous medium using 1% pyridine in methanol, respectively.The formed complexes were absorbed maximally at A, 290 nm and at X 287 nm. The method determined from 112–1620 g/mL of acyclovir, with a mean percentage of recovery of 99.32 ± 0.63 and of 98.77 ± 0.70 for copper (II) and cobalt (III), respectively.The suggested method was applied to a Novirus capsule, and its validity was ascertained by the standard addition technique. In addition, amantadine hydrochloride was allowed to react with iron (III) at pH 3 adjusted with 0.1 M ammonium hydroxide. The formed complex absorbed maximally at 295 nm. This method determined from 94–940 g/mL of amantadine hydrochloride with a mean percentage of recovery of 99.49 ± 0.57. The suggested method was applied to an Adamine capsule, and its validity was ascertained by the standard addition technique.     

Utility of Derivative Spectrophotometry in the Determination of Carbochromen Hydrochloride and Dipyridamole in the Presence of Their Oxidative Degradation Products

Abstract

Direct spectrophotometric methods for the determination of carbochromen hydrochloride and dipyridamole, each in the presence of its oxidative degradation products, are presented. the methods are based on the first derivative (D₁) and second derivative (D₂) spectrophotometric measurement (absolute trough, U) at 336 nm and (Peak-trough, Y) at 309–342 nm for carbochromen hydrochloride and at 240–260 nm(U) and 246–268 nm(Y) for dipyridamole. Plots of D₁ or D₂ versus concentration were linear over the concentration range of 8.00–16.00 μg/ml for carbochromen hydrochloride and 4.00–12.00 μg/ml for dipyridamole. Oxidative degradation of these drugs has been optimized with respect to hydrogen peroxide concentration. Determining the intact in coexistence with its oxidative degradation product, the proposed derivative spectrophotometric methods proved to be of high potential in correcting the systematic error appearing in the results of the A_max method due to the latter. Assaying the commercial tablets, the proposed method gave results of high accuracy and reproducibility.     

Spectrophotometric determination of nicoumalone, acebutolol hydrochloride and procainamide hydrochloride

A sensitive spectrophotometric method is described for the determination of nicoumalone (NIC), acebutolol hydrochloride (ACBH) or procainamide hydrochloride (PAH) either in pure form or in pharmaceutical formulations. The method is based on the oxidative coupling reaction through the involvement of an aromatic primary amino group (released through reduction in NIC or hydrolysis in ACBH or existing free in PAH) in the drug with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ferric chloride [Fe(III)]. The resulting chromophores are measured at 620 nm for NIC and ACBH and 580 nm for PAH. The concentration measurements are reproducible within a relative standard deviation of 1%.     

Construction and Validation of New Electrochemical Carbon Nanotubes Sensors for Determination of Acebutolol Hydrochloride in Pharmaceuticals and Biological Fluids

A simple, rapid and a highly selective method for direct electrochemical determination of acebutolol hydrochloride (AC) was developed. The developed method was based on the construction of three types of sensors conventional polymer (I), carbon paste (II) and modified carbon nanotubes (MCNTs) carbon paste (III). The fabricated sensors depend mainly on the incorporation of acebutolol hydrochloride with phosphotungstic acid (PTA) forming ion exchange acebutolol‐phosphotungstate (AC‐PT). The performance characteristics of the proposed sensors were studied. The sensors exhibited Nernstian responses (55.6 ± 0.5, 57.14 ± 0.2 and 58.6 ± 0.4 mV mol L^?1) at 25 °C over drug concentration ranges (1.0 × 10^?6‐1.0 × 10^?2, 1.0 × 10^?7‐1.0 × 10^?2 and 5.0 × 10^?8‐1.0 × 10^?2 mol L^?1 with lower detection limits of (5.0 × 10^?7, 5.0 × 10^?8 and 2.5 × 10^?8 mol L^?1 for sensors (I), (II) and (III), respectively. The influence of common and possible interfering species, pharmaceutical additives and some related pharmacological action drugs was investigated using separate solution method and no interference was found. The stability indicating using forced degradation of acebutolol hydrochloride was studied. The standard addition method was used for determination of the investigated drug in its pharmaceutical dosage forms and biological fluids. The results were validated and statistically analysed and compared with those from previously reported methods.     

Spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in bulk and pharmaceutical preparation

Two new, sensitive and selective spectrofluorimetric and spectrophotometric methods have been developed for the determination of the gamma-amino-n-butyric acid derivative pregabalin (PGB) in bulk drug and capsule. Pregabalin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) which is a highly sensitive fluorogenic and chromogenic reagent used in many investigations. According to this fact, spectrophotometric and spectrofluorimetric methods for the determination of pregabalin in capsules were developed for the first time. The relation between the absorbance at 460 nm and the concentration is rectilinear over the range 0.5-7.0 microg mL(-1). The reaction product was also measured spectrofluorimetrically at 558 nm after excitation at 460 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-400 ng mL(-1). The method was applied successfully to the determination of this drug in pharmaceutical dosage form. The mean recovery for the commercial capsules was 99.93% and 99.96% for spectrophotometric and spectrofluorimetric study, respectively. The suggested procedures could be used for the determination of PGB in pure and capsules being sensitive, simple and selective.     

Spectrophotometric Determination of Some Fluoroquinolone Antibacterials by Ion‐pair Complex Formation with Cobalt (II) Tetrathiocyanate

A new simple extractive spectrophotometric method has been developed for the determination of levofloxacin (I), norfloxacin (II), and ciprofloxacin (III) in pure form and tablets. The method is based on the formation of blue‐colored ion‐pair associates between the drugs and the inorganic complex, cobalt (II) thiocyanate, at pH 2.5. Those ion‐pair associates are readily extracted into an n‐butanol‐dichloromethane solvent mixture (3.5:6.5) and determined spectrophotometrically at 623 nm. The concentration range is 20–240 μg mL^?1 for the three studied drugs. The proposed method was successfully applied to determine these drugs in their tablet formulations, and the results are in good agreement with those obtained by the reference methods.     

Spectrophotometric determination of tetracycline and oxytetracycline in pharmaceutical preparations

A simple, rapid and sensitive spectrophotometric procedure for the assay of tetracycline hydrochloride and oxytetracycline hydrochloride has been developed. 2,2-Diphenyl-l-picrylhydrazyl (DPH), an intensely violet-coloured stable free radical, is changed in colour on reaction with the antibiotics investigated. The decrease in the intensity of the violet colour is used to measure the concentration of the drug. All measurements are made at 520 nm on methanolic solutions of the drug and reagent, buffered at pH 6. Beer's law is obeyed in the concentration ranges 2.5-15 and 2.5-20 mug/ml for tetracycline and oxytetracycline respectively. The proposed method has been successfully applied to analysis of the bulk drugs and their pharmaceutical formulations.     

Micro-determination of warfarin sodium, nicoumalone and acebutolol hydrochloride in pharmaceutical preparations

A simple, selective and sensitive spectrophotometric method has been developed for the determination of microgram quantities of warfarin sodium (WS), nicoumalone (NIC) and acebutolol hydrochloride (ACBH), either in pure form or in pharmaceutical preparations. This method is based on the haloform reaction with a known and excess of standard iodine solution under alkaline conditions. The excess of iodine is determined at pH 3.0 with metol-INH. The absorbance of the resulting p-N-methyl-benzoquinonemonoimine-INH charge-transfer complex is measured at 620 nm.     

Spectrofluorimetric and Spectrophotometric Stability‐Indicating Methods for the Analysis of Veralipride in Presence of Its Degradants and in Spiked Human Plasma

Spectrofluorimetric and spectrophotometric stability‐indicating methods were developed and validated for analysis of veralipride (Ver) in presence of its hydrolytic and oxidative degradants. The spectrofluorimetric method was based on direct measurement of the intrinsic fluorescence of Ver at 366 nm after excitation at 299 nm using sodium lauryl sulfate (SLS) as micelle enhancer. The fluorescence intensity plot was linear over the concentration range 1.0–10.0 µg·mL^?1. The high sensitivity of the method allowed its successful application to the analysis of Ver in spiked human plasma. Two other methods were developed. They are based on the oxidative coupling reaction of Ver with 3‐methyl benzothiazolin‐2‐one hydrazone (MBTH) hydrochloride in presence of ceric ammonium sulphate in an acidic medium. The first method depends on spectrophotometric measurement of the stable green colored oxidative coupling product at 660 nm. The different experimental parameters affecting the reaction were optimized. Linearity range is 10.0–100.0 µg·mL^?1. The second method depends on a fluorescence quenching effect of Ver on the fluorescence of Ce³⁺. The difference in fluorescence intensity was measured at 380 nm after excitation at 300 nm. This method is applicable over the concentration ranges 0.25–2.50 µg·mL^?1. The methods were validated according to the ICH guidelines. They were successfully applied for the analysis of Ver in drug substance, drug product and in laboratory prepared mixtures containing different percentages of hydrolytic and oxidative degradants.     

Spectrofluorimetric determination of two β-agonist drugs in bulk and pharmaceutical dosage forms via derivatization with dansyl chloride

A sensitive, simple and rapid spectrofluorimetric method has been developed for the determination of both Fenoterol hydrobromide (FNT) and Ritodrine hydrochloride (RTH) in pure and dosage forms. The method is based on derivatization using dansyl chloride (DNS-Cl) as fluorogenic agent and measuring the fluorescence of the products at emission wavelengths of 517 and 515 nm after excitation at 348 and 343 nm for FNT and RTH, respectively. Different experimental parameters affecting the fluorescence intensities were carefully studied and optimized. The relation between fluorescence intensities and drug concentrations were rectilinear over the concentration range of 0.25–6.0 μg/mL for both drugs with a minimum detectability of 0.065 and 0.045 μg/mL for FNT and RTH, respectively. The percentage recoveries ±SD were 100.1 ± 0.9, 99.9 ± 0.6 for FNT and RTH respectively. The proposed method was successfully applied to the determination of both drugs in their commercial dosage forms. The obtained results were statistically validated and agreed well with those obtained with reference methods. A suggestion for the reaction pathway with DNS-Cl was postulated.     

Application of H-point standard additions method to spectrophotometric and spectrofluorimetric determinations of glafenine and glafenic acid in mixtures

H-point standard additions method (HPSAM), based on spectrophotometric and spectrofluorimetric measurements, was proposed for simultaneous determination of glafenine (G) and glafenic acid (GA). A study of the absorption spectra of G and GA in various pH media has been carried out. Reasonably resolved UV-absorption spectra were obtained with a solution adjusted at pH 4.5 with citric acid–phosphate buffer. Additionally, the fluorescence properties in aqueous micellar systems of anionic, cationic and non-ionic surfactants were investigated. Well resolved fluorescence spectra were established in aqueous Triton X-100 solution at pH 7.8 (citric acid–phosphate buffer). As a comparative method, UV-derivative spectrophotometry (based on zero-crossing technique) was suggested. First-derivative value at 352 nm (¹D₃₅₂) and second-derivative value at 366 nm (²D₃₆₆) were selected for the quantification of G and GA, respectively. The relative standard deviations of the proposed methods approximate 2%. The proposed methods were evaluated through the analysis of commercial tablets. The results were accurate and precise.     

Spectrophotometric determination of some anti-tussive and anti-spasmodic drugs through ion-pair complex formation with thiocyanate and cobalt(II) or molybdenum(V)

Two rapid, simple and sensitive extractive specrophotometric methods has been developed for the determination of anti-tussive drugs, e.g., dextromethorphan hydrobromide (DEX) and pipazethate hydrochloride (PiCl) and anti-spasmodic drugs, e.g., drotaverine hydrochloride (DvCl) and trimebutine maleate (TM) in bulk and in their pharmaceutical formulations. The proposed methods depend upon the reaction of cobalt(II)-thiocyanate (method A) and molybdenum(V)-thiocyanate ions (method B) with the cited drugs to form stable ion-pair complexes which extractable with an n-butnol-dichloromethane solvent mixture (3.5:6.5) and methylene chloride for methods A and B, respectively. The blue and orange red color complexes are determined either colorimetrically at lambdamax 625 nm (using method A) and 467 or 470 nm for (DEX and PiCl) or (DvCl and TM), respectively (using method B). The concentration range is 20-400 and 2.5-50 microg mL-1 for methods A and B, respectively. The proposed method was successfully applied for the determination of the studied drugs in pure and in pharmaceutical formulations applying the standard additions technique and the results obtained in good agreement well with those obtained by the official method.     

Extractive spectrophotometric determination of fluoroquinolones and antiallergic drugs in pure and pharmaceutical formulations.

A simple, rapid and sensitive spectrophotometric procedure has been proposed for the assay of fluoroquinolones viz., ciprofloxacin (CPF) and norfloxacin (NRF), and antiallergic drugs viz., methdilazine hydrochloride (MDH) and isothipendyl hydrochloride (IPH) in bulk and pharmaceutical formulations. The method is based on the reaction of selected drugs with Brilliant Blue G (BBG) in NaOAc-AcOH buffer of pH 4.0 for CPF and NRF or in neutral medium for MDH and IPH to give chloroform soluble ion-association complexes. The effects of various parameters have been studied. The ion-association complexes exhibited absorption maxima at 610 nm for CPF, at 614 nm for NRF and MDH, and at 612 nm for IPH. Beer's law plots were obeyed in the concentration ranges of 0.5-6.0, 0.4-8.0, 0.1-6.0 and 0.2-6.1 (mg ml(-1) for CPF, NRF, MDH and IPH, respectively, with correlation coefficients not less than 0.9969. Molar absorptivity values as calculated from the Beer's law data were found to be 2.86 x 10(4), 2.64 x 10(4), 3.13 x 10(4) and 5.51 x 10(4) mol(-1) cm(-1) for CPF, NRF, MDH and IPH, respectively. The influence of commonly employed excipients in the determination of the studied drugs has been studied. The results obtained by the proposed method were statistically validated.     

New,simple, and validated UV-spectrophotometric method for the estimation of some beta blockers in bulk and formulations

A sensitive, extraction, derivatization, evaporation and complexation-free, direct spectrophotometric method is developed for the determination of some anthypertensive drugs such as acebutolol hydrochloride (ACH), atenolol (ATE), and propranolol hydrochloride (PRH) in bulk and pharmaceutical formulations. The optimum conditions for the analysis of aqua solutions of drugs are established. The method permits the determination of ACH, ATE, and PRH over a concentration range of 37.3–111.9, 53.3–213.1 and 14.8–51.8 μg/mL, respectively. Detection and quantification limits are calculated. The obtained results showed good recoveries of 99.60, 99.20 and 99.80% with relative standard deviations of 0.82, 0.79 and 1.70% for ACH, ATE, and PRH, respectively. The repeatability and reproducibility of the drugs for aqua media are determined. Precision and accuracy of the developed methods are used for the recovery studies. The proposed method is applicable for the assay of the three drugs under investigation in dosage forms and the results are in good agreement with those obtained by the literature method. The text was submitted by the author in English.