Sensitive and selective spectrophotometric determination of pantoprazole sodium in pharmaceuticals using permanganate

A simple visible spectrophotometric method is described for the determination of pantoprazole sodium sesquihydrate (PSS). The method is based on the formation of a brown colored product on treating PSS with permanganate in neutral medium, the absorbance being measured at 350 nm. The experimental conditions for the assay were optimized. The absorbance is found to increase linearly with the concentration of PSS and the calibration graph is linear in the range of 2.5-40.0 μg ml-1 with a linear regression coefficient of 0.998. The calculated molar absorptivity value is 1.27x104 l mol-1 cm-1 and the corresponding Sandel sensitivity is 0.0341 µg cm-2. The limits of detection (LOD) and quantification (LOQ) are calculated to be 0.49 and 1.47 µg ml-1, respectively. Intra-day and inter-day accuracy expressed as relative error were better than 2.0% and the corresponding precision (RSD) was less than 2.5 %. The developed and validated method was applied to the determination of the active ingredient in a tablet dosage form and the results obtained agreed well with those of the reference method. The accuracy and reliability of the method were ascertained by performing recovery experiments via standard-addition procedure

SIMPLE AND SENSITIVE SPECTROPHOTO¬METRIC ASSAY OF OFLOXACIN IN PHARMACEUTICALS BASED ON ION-PAIR REACTION

Two simple, sensitive, economical and extraction-free spectrophotometric methods have been developed for the determination of ofloxacin (OFX) in pure form and in tablets. The methods are based on the interaction of OFX with two sulphonphthalein dyes, namely, bromothymol blue (method A) and bromophenol blue (method B) in dichloromethane medium to form stable, yellow-colored ion–pair complexes peaking at 410 nm. Under the optimum conditions, OFX could be assayed in the concentration ranges 1.25-20 and 1.0-16 µg mL-1 OFX by methods A and B, respectively, with correlation coefficient of 0.999 in both methods. The apparent molar absorptivity values are calculated to be 1.74104 and 2.18104, L moL-1 cm-1, for method A and B, respectively, with corres¬pond¬ing Sandell sensitivity values of 0.021 and 0.017 µg cm-2. The limits of detec¬tion (LOD) and quantification (LOQ) are also reported. The stoichiometry of the reaction was found to be 1:1 in both cases and the conditional stability cons¬tants (Kf) of the complexes have also been reported. The intra-day and inter-day variation was assessed. The methods were applied to determine OFX from marked tablet formulations. Statistical analysis proved that the proposed methods were both accurate and precise

Modulation of MUC1 mucin as an escape mechanism of breast cancer cells from autologous cytotoxic T-lymphocytes

MUC1 mucin is known to serve as a target molecule in the killing of breast cancer cells by cytotoxic T-lymphocytes (CTLs). We searched for a possible mechanism allowing tumour cells to escape from autologous CTLs. When the killing of breast cancer cells by autologous lymphocytes was examined in 26 patients with breast cancer, significant tumour cell lysis was observed in 8 patients, whereas virtually no autologous tumour cell lysis was detected in as many as 18 patients. In the patients who showed negligible tumour cell lysis, the autologous tumour cells expressed MUC1-related antigenic epitopes much more weakly than the tumour cells in the patients who exhibited strong cytotoxicity (significant statistically at P< 0.0005–0.0045), suggesting that the unresponsiveness of cancer cells to CTLs observed in these patients was mainly due to loss of MUC1 expression or modulation of its antigenicity. A breast cancer cell line, NZK-1, established from one of the cytotoxicity-negative patients, did not express MUC1 and was resistant to killing by CTLs, while control breast cancer cell lines expressing MUC-1 were readily killed by CTLs. Transfection of NZK-1 cells with MUC1 cDNA induced significant lysis by autologous T-lymphocytes. These results supported the importance of MUC1 mucin in autologous anti-tumour immunity, but suggested that the major escape mechanism of tumour cells from autologous T-lymphocytes is the loss and/or modulation of MUC1 antigenicity on tumour cells, which would limit the effectiveness of possible immunotherapy designed to target the MUC1 mucin. © 2001 Cancer Research Campaign http://www.bjcancer.co

Spectrophotometric determination of famotidine using sulphonphthalein dyes

Four new extraction-free spectrophotometric methods have been established for the quantitation of famotidine (FMT). The methods are based on the formation of yellow ion-pair complexes between FMT and four sulphonphthalein dyes viz., bromothymol blue (method A), bromophenol blue (method B), bromocresol purple (method C) and bromocresol green (method D) in dioxane or acetone medium. The experimental variables such as reagent concentration, solvent medium and reaction time have been carefully optimized to achieve the highest sensitivity. The proposed methods were applied successfully to the determination of famotidine in tablets with good accuracy and precision and without interferences from common excipients. The results obtained by the proposed methods were compared favorably with those of the reference method

Application of Oxidizing Properties of Permanganate to the Determination of Famotidine in Pharmaceutical Formulations

One titrimetric and two spectrophotometric methods are described for the determination of famotidine (FMT) in either pure form or in its pharmaceutical formulations. The methods are based on redox reaction between FMT and KMnO(4) in acid and alkaline media. In titrimetry, an acidified solution of FMT is titrated directly with permanganate. Direct spectrophotometry (method A) involves treating the alkaline solution of the drug with permanganate and measuring the bluish green product at 610 nm. In indirect spectrophotometry (method B), the drug solution is treated with a fixed concentration of permanganate in H(2)SO(4) medium, and after a specified time, the unreacted permanganate is measured at 545 nm. The molar combining ratio in titrimetry and the optimum assay conditions are studied. Titrimetry is applicable over 1-10 mg range and the calculations are based on a 1:3 (FMT: KMnO(4)) molar-ratio. In spectrophotometry, Beer's law is obeyed over 0.75-7.5 and 2.5-20 mu g mL(-1) for method A and method B, respectively. The molar absorptivity values are calculated to be 2.79 x 10(4) and 1.62 x 10(4) L mol(-1) cm(-1) for method A and method B, respectively, and the corresponding Sandell sensitivity values are 0.012 and 0.021 mu g cm(-2). The limits of detection (LOD) and quantification (LOQ) are also reported for the spectrophotometric methods. The applicability of the developed methods was demonstrated by the determination of FMT in pure drug as well as in commercial dosage forms

Application of potassium permanganate to spectrophotometric assay of metoclopramide hydrochloride in pharmaceuticals

Two simple, sensitive, and cost-effective spectrophotometric methods are described for the determination of metoclopramide hydrochloride (MCP) in pharmaceutical dosage forms. The methods are based on a redox reaction between MCP and KMnO4 in alkaline and acid media. Direct spectrophotometry (method A) involves treating MCP with permanganate in an NaOH medium and measuring a bluish green product at 610 nm. In indirect spectrophotometry (method B), MCP is treated with a fixed concentration of KMnO4 in an H2SO4 medium, and after a specified time, the unreacted KMnO4 is measured at 545 nm. Under optimum assay conditions, Beer's law is obeyed over the ranges of 0.75--12.0 and 2.5--30.0 g/ml for methods A and B, respectively. Molar absorptivity values are calculated to be 2.33∙104 and 2.66∙104 l/mol cm for methods A and B, respectively, and corresponding Sandell's sensitivity values are 0.015 and 0.013 g/cm2. Limits of detection (LOD) and quantification (LOQ) are also reported. The applicability of the developed methods was demonstrated by the determination of MCP in tablet and injection forms. The accuracy and reliability of the proposed methods were further ascertained by recovery studies via standard addition technique

Sensitive and selective extraction free ion-pair complexometric determination of domperidone in pharmaceuticals and in spiked human urine

Domperidone (DOM) is a drug used as an antiemetic and to control gastrointestinal effects of dopaminergic drugs in the management of perkinsonism. Two simple, rapid, sensitive and selective extraction free spectrophotometric methods have been developed for the assay of DOM in pure drug, in pharmaceuticals and in spiked human urine sample. The methods are based on the formation of yellow ion-pair complexes between DOM and two sulphonphthalein dyes viz., thymol blue (method A) and bromothymol blue (method 13) in acetone and dichloromethane medium. The complexes showed absorption maxima at 390 nm and 410 nm in method A and method B, respectively. Reaction conditions were optimized to obtain the maximum color intensity. The absorbance was found to increase linearly with increase in concentration of DOM, which was corroborated by the calculated correlation values of 0.9991 in method A and 0.9986 in method B. The systems obeyed Beer's law over the concentration range of 1.25 - 20 mu g mL(-1) in both the methods. The molar absorptivity values are calculated to be 1.53 x 10(4) and 2.06 x 10(4) L mol(-1) cm(-1) for method A and method B, respectively and the corresponding Sandell sensitivity values are 0.028 and 0.021 mu g cm(-2). The composition of the ion-pairs was found to be 1 : 1 by Job's method and the conditional stability constant (K(f)) of the complexes have been calculated. The proposed methods were applied successfully to the determination of DOM in tablets as well as in spiked urine sample with good accuracy and precision