Spectrophotometeric Determination of Cefuroxime Axetil from bulk and in its tablet dosage form

A simple rapid spectrophotometric method has been developed for estimation of cefuroxime axetil from bulk drug and tablet dosage form by using 1-nitroso-2-napthol and sodium hydroxide. The method is based on the formation of yellow-orange coloured complex of drug with 1-nitroso-2-napthol having absorbance maxima at 424 nm. The Beer’s law is obeyed in the concentration range of 10-50 μg/ml of the drug but more precisely it obeys in the range of 10- 30 μg/ml. The slope and intercept values are 0.0101 and 0.0838, respectively. Results of analysis of this method were validated statistically and by recovery studies. The method is applied to the marketed tablet formulation. Result of analysis of tablet formulation given as percentage of label claim ±standard deviation is 99.17±1.57. The precision and accuracy was examined by performing recovery studies and was found to be 99.50±1.82. Sandell’s correlation coefficient is calculated as 0.4434. The developed method is simple, sensitive and reproducible and can be used for routine analysis of cefuroxime axetil from bulk and tablet dosage form.     

Extractive spectrophotometric methods for determination of diltiazem HCl in pharmaceutical formulations using bromothymol blue, bromophenol blue and bromocresol green

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of diltiazem hydrochloride either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbance maxima at 415 nm for all three methods. Beer's law is obeyed in the concentration ranges 2.5-20.0, 2.5-10.0 and 2.5-12.5 microg ml(-1) with BTB, BPB and BCG, respectively. The methods have been applied to the determination of drug in commercial tablets and capsules. Results of analysis were validated statistically and through recovery studies.     

Flow-injection spectrophotometric methods for the determination of tenoxicam

Two sensitive and rapid flow-injection spectrophotometric methods are proposed for the determination of tenoxicam (TX). In the first method, a Fe(III)-tenoxicam complex is formed in a methanolic medium and the absorbance is measured at 540 nm, while the second method involves measurement of the absorbance at 355 nm of a solution containing the drug in hydrochloric acid medium. In both methods, the peak heights were proportional to tenoxicam concentration over the ranges 7.0-320 and 0.5-8.5 mg/l(-1), respectively. The methods have been applied to the routine determination of the drug in dosage forms.     

Simple extractive colorimetric determination of levofloxacin by acid-dye complexation methods in pharmaceutical preparations

Two simple and sensitive extractive spectrophotometric methods have been described for the assay of levofloxacin (LVFX) either in pure form or in pharmaceutical formulations. The developed methods involve formation of colored chloroform extractable ion-pair complexes (1:1 and 1:2 drug/dye) of levofloxacin with bromophenol blue (BPB) and bromocresol green (BCG) in aqueous acidic medium. The extracted complexes showed absorbance maxima at 424 and 428 nm for LVFX-BPB and LVFX-BCG, respectively. Beer's law is obeyed in the concentration ranges 1.85-31.5 and 1.85-25 microg ml(-1) with BPB and BCG, respectively. The methods have been applied to the determination of drug in commercial tablets. Results of analysis were validated statistically. The excipients present in the formulations do not interfere with the assay procedure.     

Prooxidant action of rhodizonic acid: transition metal-dependent generation of reactive oxygen species causing the formation of 8-hydroxy-2'-deoxyguanosine formation in DNA.

Rhodizonic acid, a six-membered cyclic hydroxyquinone, produced reactive oxygen species as a complex with transition metals. Addition of rhodizonic acid with ferrous ion caused an inactivation of aconitase the most sensitive enzyme to oxidative stress in permeabilized yeast cells. The iron-dependent inactivation of aconitase implies the rhodizonic acid/iron-mediated generation of reactive oxygen species. Spectrophotometric analysis of the interaction of rhodizonic acid with FeSO4 showed that addition of superoxide dismutase could inhibit the oxidation of rhodizonic acid, suggesting that reactive oxygen species produced from rhodizonic acid is superoxide radical. Rhodizonic acid further acted as a prooxidant causing a copper-dependent DNA damage. Treatment of DNA from plasmid pBR322 and calf thymus with rhodizonic acid plus copper caused strand scission and the formation of 8-hydroxy-2'-deoxyguanosine in DNA. Addition of catalase protected DNA from the rhodizonic acid-mediated strand scission, indicating that hydroxyl radical may participate in the DNA damage. Rhodizonic acid also showed a potent copper-reducing activity. These results indicate that copper ion reduced by rhodizonic acid may participate in the formation of superoxide radical that converts to hydrogen peroxide and hydroxyl radical. Other cyclic hydroxyquinones such as four-membered squaric acid and five-membered croconic acid did not show any prooxidant and reducing effects. Cytotoxic effects of tetrahydroquinone the precursor of rhodizonic acid may be related to the prooxidant properties of rhodizonic acid formed in cells.     

HPLC and chemometric methods for the simultaneous determination of cyproheptadine hydrochloride, multivitamins, and sorbic acid

Three methods are presented for the simultaneous determination of cyproheptadine hydrochloride (CP), thiamine hydrochloride (B1), riboflavin-5-phosphate sodium dihydrate (B2), nicotinamide (B3), pyridoxine hydrochloride (B6), and sorbic acid (SO). The chromatographic method depends on a high performance liquid chromatographic (HPLC) separation on a reversed-phase, RP 18 column. Elution was carried out with 0.1% methanolic hexane sulphonic acid sodium salt (solvent A) and 0.01 M phosphate buffer containing 0.1% hexane sulphonic acid sodium salt, adjusted to an apparent pH of 2.7 (solvent B). Gradient HPLC was used with the solvent ratio changed from 20:80 to 70:30 (over 9 min), then to 80:20 (over 11 min) for solvent A:B, respectively. Quantitation was achieved with UV detection at 220 and 288 nm based on peak area. The other two chemometric methods applied were principal component regression (PCR) and partial least squares (PLS). These approaches were successfully applied to quantify each drug in the mixture using the information included in the UV absorption spectra of appropriate solutions in the range 250-290 nm with the intervals Deltalambda = 0.4 nm at 100 wavelengths. The chemometric methods do not require any separation step. The three methods were successfully applied to a pharmaceutical formulation and the results were compared with each other.     

Optimized and validated spectrophotometric methods for the determination of nicorandil in drug formulations and biological fluids

Two simple, sensitive and economical spectrophotometric methods have been developed for the determination of nicorandil in drug formulations and biological fluids. Method A is based on the reaction of the drug with brucine-sulphanilic acid reagent in sulphuric acid medium producing a yellow-coloured product, which absorbs maximally at 410 nm. Method B depends on the formation of the intensely blue-coloured product which results due to the interaction of an electrophilic intermediate of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) with oxidized product of 4-(methyl amino) phenol sulphate (metol) in the presence of nicorandil as an oxidizing agent in sulphuric acid medium. The coloured product shows absorbance maximum at 560 nm. Under the optimized experimental conditions, Beer's law is obeyed in the concentration range of 2.5-35.0 and 0.40-2.2 microg ml(-1) for Methods A and B, respectively. Both the methods have been successfully applied to the determination of nicorandil in drug formulations and biological fluids. The results are validated statistically and through recovery studies. In order to establish the bias and the performance of the proposed methods, the point and interval hypothesis tests have been performed. The experimental true bias of all samples is smaller than +/-2%.     

Spectrophotometric methods for determining meloxicam in pharmaceuticals using batch and flow-injection procedures.

Two sensitive and fast spectrophotometric methods using batch and flow-injection procedures for the determination of meloxicam (MX) are proposed. The methods are based on the formation of a green complex between this drug and Fe(III) [2MX/Fe(III)] in a methanolic medium. The calibration graphs resulting from measuring the absorbance at 570 nm are linear over the ranges 2.0-200 and 5.00-250 mg l(-1) with detection limits of 0.47 and 0.72 mg l(-1), respectively. Furthermore, a flow-injection spectrophotometric method involving measurement of the absorbance of the drug at 362 nm in 0.1 M NaOH is presented. The calibration graph is linear over the range 0.5-20 mg l(-1) with a detection limit of 0.04 mg l(-1). The methods are applied to the routine analysis of MX in pharmaceuticals.     

Spectrophotometric determination of fluoxetine hydrochloride in bulk and in pharmaceutical formulations

Two new rapid, sensitive and economical spectrophotometric methods are described for the determination of fluoxetine hydrochloride in bulk and in pharmaceutical formulations. Both methods are based on the formation of a yellow ion-pair complex due to the action of methyl orange (MO) and thymol blue (TM) on fluoxetine in acidic (pH 4.0) and basic (pH 8.0) medium, respectively. Under optimised conditions they show an absorption maxima at 433 nm (MO) and 410 nm (TB), with molar absorptivities of 2.12 x 10(-4) and 4.207 x 10(-3) l mol(-1) cm(-1) and Sandell's Sensitivities of 1.64 x 10(-2) and 0.082 microg cm(-2) per 0.001 absorbance unit for MO and TB, respectively. The colour is stable for 5 min after extraction. In both cases Beer's Law is obeyed at 1-20 microg mol(-1) with MO and 4-24 microg mol(-1) with TB. The proposal method was successfully extended to pharmaceutical preparations capsules. The results obtained by both the agreement and E.P. (3rd edition) were in good agreement and statistical comparison by Student's t-test and variance ratio F-test showed no significant difference in the three methods.     

复方薄荷脑苯酚搽剂质量标准研究

目的 建立复方薄荷脑苯酚搽剂中水杨酸和苯酚的定量分析方法.方法 采用紫外-可见分光光度法测定水杨酸的含量,检测波长为300 nm;采用高效液相色谱法测定苯酚含量,色谱柱为Agilent Zorbax SB-C18柱(250 mm×4.6 mm,5μm),流动相为甲醇-水(48:52,V/V),流速为1.0 mL/min...     

Spectrophotometric determination of carvedilol in pharmaceutical formulations through charge-transfer and ion-pair complexation reactions

Simple extraction-free spectrophotometric methods have been developed for the determination of carvedilol (CAR). The methods were based either on charge-transfer reaction of the drug with the sigma-acceptor iodine, in acetonitrile, or on ion-pair formation with the acidic sulphophthalein dyes bromothymol blue (BTB) and bromocresol green (BCG), in chloroform. The obtained complexes showed absorbance maxima at 363, 411 and 414 nm, respectively for iodine, BTB and BCG. Beer's law validation, accuracy, precision, and other aspects of analytical merit are presented in the text. The proposed methods were applied for the determination of CAR in tablets and compounded capsules. The results were in good agreement with those obtained by an established UV spectrophotometric method.     

A simple kinetic spectrophotometric method for the determination of oxamniquine in formulations and spiked biological fluids

A simple and sensitive kinetic method for the determination of oxamniquine in pharmaceutical preparations and biological fluids was developed. The procedure is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permanganate at room temperature for a fixed time of 20 min. The absorbance of the colored manganate ions was measured at 610 nm. Alternatively, the decrease in the absorbance of potassium permanganate after addition of the drug was measured at 525 nm. The absorbance concentration plots in both procedures were rectilinear over the range 0.5-4 microg ml(-1). The concentration of oxamniquine is calculated using the corresponding calibration equation for the fixed-time method. The determination of oxamniquine by fixed-concentration and rate-constant methods was feasible with the calibration equations obtained but the fixed time method had been found to be more applicable. Both procedures were applied to the determination of oxamniquine in formulations. The results obtained were in good agreement with those obtained using the official method. The fixed time method of 20 min was further applied to spiked human urine and plasma, the recoveries (%) were 100.94 +/- 0.57 and 98.07 +/- 0.88 for urine and plasma, respectively, at 610 nm, and 97.51 +/- 1.27 and 95.69 +/- 1.23 for urine and plasma, respectively, at 525 nm.     

RP-HPLC and Spectrophotometric Estimation of Ambroxol Hydrochloride and Cetirizine Hydrochloride in Combined Dosage Form

Rapid, precise, accurate, specific and sensitive reverse phase liquid chromatographic and absorbance ratio spectrophotometric methods have been developed for the simultaneous analysis of ambroxol hydrochloride and cetirizine hydrochloride in their tablet formulation. The chromatographic methods were standardized using a HIQ SIL-C(18) column (250×4.6 mm i.d., 10 μm particle size) with UV detection at 229 nm and mobile phase consisting of methanol-acetonitrile-water (40:40:20, v/v/v). Ambroxol hydrochloride and cetirizine hydrochloride have absorbance maxima at 243 nm and 229 nm, respectively. The isoabsorptive wavelength for both the drugs was 236 nm. For absorbance ratio method developed, wavelengths selected were 243 nm and 236 nm. The proposed methods were successfully applied to the determination of ambroxol hydrochloride and cetirizine hydrochloride in tablets, with high percentage of recovery, good accuracy and acceptable precision. Different analytical performance parameters such as linearity, precision, accuracy, limit of detection, limit of quantitation and robustness were determined according to International Conference on Harmonization ICH Q2B guidelines. Results of analysis of the developed method were compared by performing ANOVA.     

New, simple and validated UV-spectrophotometric methods for the estimation of gatifloxacin in bulk and formulations

New, simple and cost effective UV-spectrophotometric methods were developed for the estimation of gatifloxacin in bulk and pharmaceutical formulations. Gatifloxacin was estimated at 286 nm in 100 mM phosphate buffer (pH 7.4) and 292 nm in 100 mM hydrochloric acid (pH 1.2). Linearity range was found to be 1-18 mug ml(-1) (regression equation: absorbance=0.0684 x Concentration in microg ml(-1) + 0.0050; r2 = 0.9998) in the phosphate buffer (pH 7.4) and 1-14 microg ml(-1) (regression equation: absorbance = 0.0864 x Concentration in microg ml(-1) + 0.0027; r2 = 0.9999) in hydrochloric acid medium (pH 1.2). The apparent molar absorptivity was found to be 2.62 x 10(4) l mol(-1) cm(-1) in the phosphate buffer and 3.25 x 10(4) l mol(-1) cm(-1) in hydrochloric acid media. In both the proposed methods sandell's sensitivity was found to be about 0.01 microg cm(-2)/0.001A. These methods were tested and validated for various parameters according to ICH guidelines and USP. The quantitation limits were found to be 0.312 and 0.3 microg ml(-1) in the phosphate buffer and hydrochloric acid medium, respectively. The proposed methods were successfully applied for the determination of gatifloxacin in pharmaceutical formulations (tablets, injection and ophthalmic solution). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%), while being simple, cheap and less time consuming and can be suitably applied for the estimation of gatifloxacin in different dosage forms and dissolution studies.     

Spectrophotometric determination of labetalol in pharmaceutical preparations and spiked human urine

Two simple and sensitive spectrophotometric methods were developed for the spectrophotometric determination of labetaolol (LBT). Both methods are based on the phenolic nature of the drug. The first method (Method I) is based on coupling LBT with diazotized benzocaine in presence of trimethylamine. A yellow colour peaking at 410 nm was produced and its absorbance is linear with the concentration over the range 1-10 microg ml(-1) with correlation coefficient (n=5) of 0.9993. The molar absorptivity was 2.633 x 10(4) l mol(-1) cm(-1). The second method (Method II) involves coupling LBT with diazotized p-nitroaniline in presence of sodium carbonate. An orange colour peaking at 456 nm was obtained and its absorbance is linear with concentration over the range 1-10 microg ml(-1) with correlation coefficient (n=5) of 0.99935. The stoichiometry of the reaction in both cases was accomplished adopting the limiting logarithmic method and was found to be 1:1. The developed method could be successfully applied to commercial tablets. The results obtained were in good agreement with those obtained using the official methods. No interference was encountered from co-formulated drugs, such as hydrochlorothiazide. The method was further extended to the in-vitro determination of LBT in spiked human urine. The % recovery (n=4) were 97.7+/-5.75 and 103.27+/-5.42 using the Methods I and II, respectively.     

Stability-indicating methods for the determination of mosapride citrate in the presence of its degradation products according to ICH guidelines

In the present work, different spectrophotometric methods and one spectrofluorimetric method have been developed and validated for the determination of mosapride citrate in the presence of its acid-induced degradation products. The drug was subjected to stress stability study including acid, alkali, oxidative, photolytic, and thermal stress degradation. The developed spectrophotometric methods included the use of first order derivative ((1)D), derivative of ratio spectra ((1)DD), mean centring of ratio spectra (MC) and H-point standard additions (HPSAM) spectrophotometric methods. For (1)D method, the peaks amplitudes at 282.8 and 319.6 nm were measured, while for (1)DD method those at 308 nm and 323 nm were measured. Mean centring of ratio spectra method used the values at 317 nm for calibration, while for HPSAM the absorbance at 273 and 288.6 nm were used. These methods were successfully applied for determination of mosapride in the concentration range of 5-70 μg.ml(-1). The spectrofluorimetric method was based on measuring the native fluorescence of mosapride in 0.1 M NaOH using λ(excitation) 276 nm and λ(emission) 344 nm and 684 nm with linearity ranges of 50-3000 ng.ml(-1) and 50-9000 ng.ml(-1), respectively. All the developed methods were validated according to the International Conference on Harmonization (ICH) guidelines and were applied for bulk powder and dosage form. The results obtained were statistically compared to each other using one-way ANOVA testing.     

Spectrophotometric and titrimetric determination of nizatidine in capsules

Four simple and accurate methods are described for the determination of nizatidine (NIZ) in pharmaceutical preparations. The first method is based on the formation of an ion-pair complex between the drug and either of bromocresol purple or picric acid with subsequent measurement of the developed colors at 411 and 400 nm, respectively. The second method depends on the condensation of mixed anhydrides of citric acid/acetic anhydride, with the tertiary amino group of the drug, where the developed color is measured spectrophotometrically at 545 nm. The oxidation of nizatidine by N-bromosuccinimide was utilized as a basis for the titrimetric method for its assay in capsules. The last method depends on the oxidation of nizatidine by ammonium cerium IV sulfate in the presence of perchloric acid with subsequent measurement of the absorbance at 314 nm; this principle is adopted to develop a kinetic method for the determination of NIZ in capsules. All the reaction conditions have been studied. The detection limits were varied from 0.44 to 0.78 microg ml(-1). The proposed methods were successfully applied to the assay of nizatidine in capsules.     

古糖酯的稳定性研究

目的探讨古糖酯的稳定性。方法本文采用凝胶色谱(HPGC),聚丙烯酰胺凝胶电泳(PAGE),紫外扫描,明胶比浊法来考察古糖酯在高温、高湿、强光照射及加速条件下分子量和分子量分布宽度及样品中硫酸根含量的变化情况。结果这几种方法适用于古糖酯的稳定性考察,在高温60 ℃和80 ℃条件下样品有所降解,80 ℃条件下更为明显,其他条件下样品稳定性良好。结论古糖酯具有良好的稳定性。     

Determination of ranitidine hydrochloride in pharmaceutical preparations by titrimetry and visible spectrophotometry using bromate and acid dyes

Four new methods using titrimetry and spectrophotometry are described for the determination of ranitidine hydrochloride (RNH) with potassium bromate as the oxidimetric reagent and acid dyes, methyl orange, indigo carmine and metanil yellow. In direct titrimetry (method A), the drug is titrated directly with bromate in acid medium and in the presence of excess of bromide using methyl orange indicator. In back titrimetry (method B), the drug is treated with a measured excess of bromate in the presence of bromide and acid, and the unreacted bromine is determined iodometrically. Both spectrophotometric methods are based on the oxidation of RNH by a known excess of bromate in acid medium and in the presence of excess of bromide followed by estimation of surplus oxidant by reacting with either indigo carmine (method C) or metanil yellow (method D), and measuring the absorbance at 610 or 530 nm. In methods B, C and D, reacted oxidant corresponds to the drug content. The experimental conditions are optimized. Titrimetric procedures are applicable over the ranges 1-10 mg (A) and 1-17 mg (B), and the reaction stoichiometry is found to be 1:1 (BrO(-)(3): RNH). In spectrophotometric methods, the absorbance is found to increase linearly with increasing concentration of RNH, which is corroborated by the calculated correlation coefficient (r) of 0.9984 (C) and 0.9976 (D). The systems obey Beer's law for 2-12 and 1-7 microg ml(-1), for methods C and D, respectively. Method D with a molar absorptivity of 9.82 x 10(4) l mol(-l) cm(-1) is found to be more sensitive than method C ( epsilon = 2.06 x l0(4) l mol(-1) cm(-1)). The limits of detection and quantification are reported for both the spectrophotometric methods. The proposed methods were applied successfully to the determination of RNH in tablets and injections. The reliability of the assay was established by parallel determination by the official method and by recovery studies.     

Studies of complex formation between the bromophenol blue and some important aminoquinoline antimalarials

A simple and rapid colorimetric method for the assay of amodiaquine hydrochloride, chloroquine phosphate and primaquine phosphate is described. The method is based on the interaction of the drug base with bromophenol blue to give a stable ion-pair complex. The spectra of the complex shows a maxima at 415-420 nm with high apparent molar absorptivities. Beer's law was obeyed in the concentration range 1-8, 2-10 and 2-12 micrograms.ml-1 for amodiaquine hydrochloride, primaquine phosphate and chloroquine phosphate respectively. The proposed method was applied to the determination of these drugs in certain formulations and the results were favourably comparable to the official methods.