Spectroscopic interaction studies of H2 receptor antagonists with levocetirizine.

Patients with allergic rhinitis may also suffer abdominal pain, gastritis or peptic ulcer. In this condition patient may use levocetirizine with famotidine or ranitidine. These drugs have potential to interact with another drug and form complex. The aim of the present study is to evaluate the possible drug drug interaction with each other which may cause increase or decrease of therapeutic effects. For this purpose, validity of Beer Lambert law was checked, lone availability of famotidine (20gm), ranitidine (150gm) and levocetirizine (5mg) were studied in pH simulated to gastric juice (pH 1), pH 4, pH 7.4 and in pH 9 and finally percent availabilities of these drugs were calculated with the help of simultaneous equation. Results showed high percentage of levocetirizine in all pH as 300.32%, 514.41%, 173.38% and 220.68% in presence of famotidine but very low availability of famotidine as 5.36%, 35.38%, 51.87% and 10.89% in presence of levocetirizine. In the case of levocetirizine and ranitidine interaction, zero percent levocetirizine was available at pH 1and 9, 56.28% in pH 4 and 191.1% in pH 7.4. On the other hand, ranitidine was available as 95.36%, 127.93%, 41.47% and 144.3%. These results showed that percentage of all drugs were altered in presence of each other due to drug-drug interaction. This may be due to the charge transfer binding capabilities of the drugs which resulted in significantly changed availability of famotidine, ranitidine as well as levocetirizine.

Moxifloxacin-Ester derivatives: Synthesis, characterization and pharmacological evaluation.

It is known that resistance of bacteria is one of the major issues in drug treatment. To cope this issue, it is required to synthesize new analogues which contest against mutated bacteria. This research study included synthesis of several derivatives of moxifloxacin by adding different phenol and alkyl halide at third position of carboxylic group with esterification reaction and the structures of synthesized derivatives were characterized by spectroscopic techniques i.e. 1H NMR, FT-IR and mass-spectrometry. In continuation, antimicrobial activities of the analogues were also evaluated against number of Gram-positive, Gram-negative bacteria and fungi. The experimental results of novel derivatives exhibit significant antibacterial and antifungal profile in which so many synthesized derivatives influenced a similar and enhanced activity against selected microbes that were S. typhi, P. mirabilis, P. aeruginosa, S. flexneri, B. subtilis as compared to the moxifloxacin. Moreover, few innovative derivatives were also produced better anti-fungal activity against F. solani and T. rubrum. Furthermore, the enzymatic activity of all analogues has been analyzed against urease and carbonic anhydrase and concluded that C2 was selected inhibitor of urease enzyme.

Synthesis, characterization, antimicrobial and enzyme inhibitory studies of moxifloxacin with aromatic carboxylic acids.

A series of carboxamide derivatives of moxifloxacin has been synthesized. The synthesized derivatives has been characterization by using spectroscopic techniques such as UV-Vis, IR, H1NMR and Mass spectra, which suggested that incoming group has occupied azabicylo groups of selected moxifloxacin at 7th position. Antimicrobial screening has been systematically carried out against various gram-positive, Gram-negatives and fungi in comparison with parent drug. Enzymatic assay were also performed. The results obtained were statistically analyzed by one way ANOVA. The antimicrobial results reveals that the synthesized derivative of moxifloxacin possess good activities against B. subtilis, F. solani, T. rubrum and P. aeruginosa concluding that derivatives are more potent antimicrobial agents as compared to parent drug. While compound B1 solely possess mild enzymatic activity against urease whereas, no other compounds is active against both urease and carbonic anhydrase.

Investigation of interaction studies of cefpirome with ACE-inhibitors in various buffers.

This work describes a RP-HPLC method for the determination and interaction studies of cefpirome with ACE-inhibitors (captopril, enalapril and lisinopril) in various buffers. The separation and interaction of cefpirome with ACE-inhibitors was achieved on a Purospher Star, C18 (5 µm, 250×4.6 mm) column. Mobile phase consisted of methanol: water (80:20, v/v, pH 3.3); however, for the separation of lisinopril, it was modified to methanol-water (40:60, v/v, pH 3.3) and pumped at a flow rate of 1 mL min(-1). In all cases, UV detection was performed at 225 nm. Interactions were carried out in physiological pH i.e., pH 1 (simulated gastric juice), 4 (simulated full stomach), 7.4 (blood pH) and 9 (simulated GI), drug contents were analyzed by reverse phase high performance liquid chromatography. Method was found linear in the concentration range of 1.0-50.0 µg mL(-1) with correlation coefficient (r(2)) of 0.999. Precision (RSD%) was less than 2.0%, indicating good precision of the method and accuracy was 98.0-100.0%. Furthermore, cefpirome-ACE-inhibitors' complexes were also synthesized and results were elucidated on the basis of FT-IR, and (1)H NMR. The interaction results show that these interactions are pH dependent and for the co-administration of cefpirome and ACE-inhibitors, a proper interval should be given.

Facile LC-UV methods for simultaneous monitoring of ciprofloxacin and rosuvastatin in API, formulations and human serum.

An efficient, selective and cost-effective liquid chromatographic assay was developed and validated for the simultaneous quantification of ciprofloxacin and rosuvastatin in Active Pharmaceutical Ingredients (API), pharmaceutical formulations and in human serum. The chromatographic system consisted of mobile phase methanol-water, 90:10 v/v at pH 3.0 adjusted with o-phosphoric acid, pumped at 1.0 mL/min through a prepacked Purospher Star C18 (5 µm, 25 × 0.46 cm) column and effluent was monitored at the isosbestic point (255 nm) as well as at the λmax of individual drugs (243 and 271 nm). The method was validated over a linear concentration range of 0.25-15 µg/mL for ciprofloxacin and 0.33-20 µg/mL for rosuvastatin (r(2) ≥ 0.999). The ranges of reliable response (limits of detection and quantitation) for ciprofloxacin were 3-15 and 9-45 ng/mL and 17-29 and 52-88 ng/mL, respectively, for rosuvastatin in all API, pharmaceutical formulations and human serum. Analytical recovery from human serum was >98% and relative standard deviation (RSD) was <2. The accuracies were 97.13-102.55 and 97.41-101.31% and precisions in RSD were 0.04-1.90 and 0.02-1.23% for ciprofloxacin and rosuvastatin, respectively. No matrix interferences, ion suppression/enhancement and carry-over were detected. The total assay run time was less than 5 min. In another study, for optimum performance the detector was programmed for multiwavelength scanning at the absorption maxima of each component. Consequently, the linearity range was improved and limit of detection and quantitation values were down to 1-4 and 4-12 ng/mL for ciprofloxacin and 3-5 and 9-15 ng/mL for rosuvastatin, respectively. The validation parameters fitted ICH guidelines through the isosbestic and individual λmax approach. The small sample volume and simplicity of preparation make this method suitable for use in human serum samples, pharmaceutical formulations, quality control, drug-drug interaction studies, clinical laboratories, drug research centers and forensic medical centers.

Liquid chromatographic method for the simultaneous determination of captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulation, and human serum by programming the detector.

A highly sensitive LC method with UV detection has been developed for the simultaneous determination of coadministered drugs captopril, piroxicam, and amlodipine in bulk drug, pharmaceutical formulations, and human serum at the isosbestic point (235 nm) and at individual λmax (220, 255, and 238 nm, respectively) by programming the detector with time to match the individual analyte's chromophore, which enhanced the sensitivity with linear range. The assay involved an isocratic elution of analytes on a Bondapak C18 (10 µm, 25 × 0.46 cm) column at ambient temperature using a mobile phase of methanol/water 80:20 at pH 2.9 and a flow rate of 1.0 mL/min. Linearity was found to be 0.25-25, 0.10-6.0, and 0.20-13.0 µg/mL with correlation coefficient >0.998 and detection limits of 7.39, 3.90, and 9.38 ng/mL, respectively, whereas calibration curves for wavelength-programmed analysis were 0.10-6.0, 0.04-2.56, and 0.10-10.0 µg/mL with correlation coefficient >0.998 and detection limits of 5.79, 2.68, and 3.87 ng/mL, respectively. All the validated parameters were in the acceptable range. The recovery of drugs was 99.32-100.39 and 98.65-101.96% in pharmaceutical formulation and human serum, respectively, at the isosbestic point and at individual λmax . This method is applicable for the analysis of drugs in bulk drug, tablets, serum, and in clinical samples without interference of excipients or endogenous serum components.

RP-LC simultaneous quantitation of co-administered drugs for (non-insulin dependent) diabetic mellitus induced dyslipidemia in active pharmaceutical ingredient, pharmaceutical formulations and human serum with UV-detector.

BACKGROUND: Rapid, efficient and accurate RP-HPLC-UV method for the simultaneous determination and quality control of active pharmaceutical ingredient (API), pharmaceutical formulations and human serum containing drugs as rosuvastatin together with metformin, glimepiride and gliquidone has been proposed. METHODS: The chromatographic system comprised mobile phase of methanol:water 90:10 v/v; pH adjusted to 3.0 with o-phosphoric acid, at 1 ml/min through Prepacked Purospher Star C18 (5 µm, 25×0.46 cm) column with UV detection at isosbestic point 231 nm. RESULTS: The method showed good linearity in the range 0.25-25 µg/ml for metformin and 0.5-50 µg/ml for rosuvastatin, glimepiride and gliquidone with correlation co-efficient ≥ 0.998; (precision %RSD<2) for all drugs in API, formulations and human serum. The recovery of all drugs was 98.9-101.91% in API and formulations and 99.92-102.08% in human serum. The sensitivity of method increased when drugs were analyzed after programming the detector at their individual λmax where their LODs shifted down to 5, 3, 10 and 9 ng/ml from 10, 17, 15 and 14 ng/ml when calculated at their isosbestic point respectively at least concentration 0.125 µg/ml for metformin and 0.25 µg/ml for rosuvastatin, glimepiride and gliquidone with correlation co-efficient ≥ 0.998 in each case. CONCLUSIONS: The proposed drugs can be analyzed by this method for routine analysis and clinical studies with sensitivity at nanoscale with small sample volume.

RP-LC method for the simultaneous determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in formulations and human serum.

The objective of this research was to develop and validate a rapid, economical, and sensitive HPLC method for quantitative determination of gliquidone, pioglitazone hydrochloride, and atorvastatin in tablets and serum. Due to drug combination of these formulations, there has been a need for a reliable quantitative method to determine these drugs in commercial samples and human serum. The chromatographic separation was carried out at ambient temperature with a mobile phase consisting of methanol-water (90 + 10, v/v), with pH adjusted to 3.50 with phosphoric acid. The pump was operated at a flow rate of 1 mL/min, and all analytes were detected at 235 nm. The method was linear over the concentration range of 5-50 microg/mL for all the drugs. The LOD of gliquidone, pioglitazone hydrochloride, and atorvastatin was 0.30, 1.30, and 0.57 microg/mL and LOQ was 0.98, 4.28, and 1.90 microg/mL, respectively. The proposed method was successfully applied to the determination of these drugs in commercial tablets and human serum. The established method was validated with respect to specificity, linearity, precision, accuracy, and ruggedness.

Identification of anti-inflammatory and other biological activities of 3-carboxamide, 3-carbohydrazide and ester derivatives of gatifloxacin.

BACKGROUND: Seventeen 1,4-dihydroquinoline-3-carboxamide and 1,4-dihydroquinoline-3-carbohydrazide derivatives of gatifloxacin have been prepared with a facile one step synthesis aiming to improve antibacterial, antifungal and immunological activities. The methodology allows the introduction of a variety of substituents such as amines, alcohol, phenol, amides and alkyl halides into the core structure of gatifloxacin. RESULTS: The analog N-(3-aminophenyl)-1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxamide has been identified as a potentially excellent anti-inflammatory agent, which exhibited highly potent effects on the oxidative burst activity of whole blood phagocytes (IC50 <12.5 µg mL-1), neutrophils (IC50 <0.1 µg mL-1) and macrophages phagocytes (IC50 <3.1 µg mL-1) as well as potent T-cell proliferation inhibitory effect (IC50 3.7 µg mL-1) while having comparable antibacterial activity to gatifloxacin. Another analog, 1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-N-phenyl-1,4-dihydroquinoline-3-carbohydrazide has tremendous T-cell proliferation inhibitory effect IC50 <3.1 µg mL-1 as compared to prednisolone, whereas, 3,5-dihydroxyphenyl1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylate and 2-hydroxyphenyl-1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylate envision good inhibitory activity on T-cells proliferation (IC50 6.8 & 8.8 µg mL-1 respectively). CONCLUSIONS: The structural modification at carboxylic group has resulted in improved anti-inflammatory activities with comparable antibacterial activity to gatifloxacin. We believe that C3 structural modifications of gatifloxacin are definitely important in bringing major immunomodulatory changes in these compounds.

Determination of tryptophan in raw materials, rat brain and human plasma by RP-HPLC technique.

This paper describes tryptophan (TRP) estimation in raw human plasma and rat brain by reversed-phase high-performance liquid chromatography (RP-HPLC). Estimation was carried out on a Purospher STAR C18 column using water-acetonitrile (90:10 v/v, at pH 2.7) mixture at a rate of 1.5 mL/min as mobile phase. Eluents were monitored at 273 nm by an ultraviolet detector. The method was linear (R(2) > 0.999), precise (intra-day and inter-day precision <2%) in the range of 0.25-20 µg/mL. The detection and quantification limits were 0.0144 µg/mL and 0.0437 µg/mL, respectively. In human plasma, Day 1 and Day 2 precision were 0.054-2.29% and 1.66-3.7%; whereas precisions in rat brain were 1.23-2.3% and 0.677-4.2%, respectively. The method was applied to study TRP level in human smokers and in arthritic rat brain. An efficient RP-HPLC method was developed for TRP determination that worked for clinical and research purposes.

Development and validation of new assay method for the simultaneous analysis of diltiazem, metformin, pioglitazone and rosiglitazone by RP-HPLC and its applications in pharmaceuticals and human serum.

Simple, sensitive, rapid, and accurate high-performance liquid chromatographic (HPLC) method is developed and validated for the simultaneous determination of diltiazem, metformin, pioglitazone, and rosiglitazone hydrochloride in raw materials, their pharmaceutical formulations, and human serum. In HPLC, all the above drugs were chromatographed using acetonitrile-methanol-water (30:20:50, v/v, pH 2.59 ± 0.02) as the mobile phase at a flow rate of 1.0 mL/min at ambient temperature. The separation is carried out on a Hiber, 250-4.6 RP-18 column, equipped with a UV-vis detector at 230 nm. All the antidiabetic drugs eluted at different retention time and each showed a good resolution from diltiazem. The method is successfully applied to pharmaceutical formulations because no chromatographic interferences from the tablet excipients are found. The method is found to be linear, accurate, and precise with apposite detection and quantification limit. Suitability of the method for the quantitative determination of the drugs is proven by validation in accordance with the requirements laid down by International Conference on Harmonization (ICH) guidelines. The validation results, together with statistical treatment of the data, demonstrated the reliability of this method.

Development and validation of stability-indicating HPLC method for the simultaneous determination of paracetamol, tizanidine, and diclofenac in pharmaceuticals and human serum.

A method is described for the simultaneous determination of paracetamol, tizanidine, and diclofenac in mixtures. The method was based on HPLC separation of the three drugs followed by UV detection at 254 nm. The separation was carried out on a Hypersil ODS, C18 (250 x 4.6 mm id, 10 microm particle size) column using the mobile phase aqueous 0.2% ammonium carbonate-methanol (60 + 40, v/v) at a flow rate of 1 mL/min. The linear regression analysis data were used for the regression curve in the range of 170-10 000 ng/mL for paracetamol, 120-10 000 ng/mL for tizanidine, and 20-10 000 ng/mL for diclofenac. No chromatographic interference from tablet excipients was found. In order to check the selectivity of the proposed method, degradation studies were carried out using hydrolysis (acid, basic, and neutral), thermolysis, and oxidation. The developed method, after being validated in terms of precision, robustness, recovery, LOD, and LOQ, was successively applied to the analysis of pharmaceutical formulations and human serum.

Validated RP-HPLC method for determination of permethrin in bulk and topical preparations using UV-vis detector.

An isocratic reversed-phase high-performance liquid chromatographic method for the estimation of permethrin in raw materials and pharmaceutical topical preparations has been devised and validated. The chromatographic analysis was performed on a 5 µm particle C-18 Nucleosil (Macherey-Nagel, Germany) column (250 × 4.6 mm). Mobile phase consisted of methanol and 0.025 mM Phosphoric acid (85:15 v/v) at a flow rate of 1.5 mL/min. UV detection was performed at 272 nm and peaks were identified with retention times as compared with standards. The limit of detection was 1.782 µg/mL, while limit of quantitation was 48.0 µg/mL. The calibration was linear in a concentration range of 48.0-5000 µg/mL with correlation coefficient of 0.999978. Regression equation was absorbance =2833.23 × concentration(µg/mL) + 19.1045 with variance of the response variable, S(yx)(2), calculated to be 1.75328 (six degrees of freedom). The method was validated as per ICH guidelines and USP requirements and found advantageous for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving permethrin.

Simultaneous determination of gliquidone, pioglitazone hydrochloride, and verapamil in formulation and human serum by RP-HPLC.

In the present study, a reverse-phase high performance liquid chromatography method was developed, validated and applied for the simultaneous determination of gliquidone, pioglitazone hydrochloride and verapamil in tablets and human serum. Chromatographic separation was achieved on a C18 column (5 µm, 25 × 0.46 cm) with a mobile phase consisting of methanol-water-acetonitrile (80:10:10 v/v/v) with a flow rate of 0.7 mL/min and pH adjusted to 3.50 with phosphoric acid at 230 nm. Glibenclamide was used as internal standard. The experimentally derived limit of detection and limit of quantitation were determined to be 0.24, 0.93, 0.40, and 0.80, 3.11, 1.36 µg/mL for gliquidone, pioglitazone, and verapamil, respectively. There were no interfering peaks due to the excipients present in the pharmaceutical tablets. Thus, the proposed method is simple and suitable for the simultaneous analysis of active ingredients in dosage forms and human serum.

Simultaneous determination of clopidogrel and aspirin by RP-HPLC from bulk material and dosage formulations using multivariate calibration technique.

A rapid, simple, and easy method for the simultaneous determination of clopidogrel and aspirin from bulk material and dosage formulations in the presence of meloxicam as internal standard has been developed. Separation was carried out on a Purospher star C(18) (5 µm, 250 × 4.6 mm) column at ambient temperature. The mobile phase consisted of methanol-water (80:20, v/v), the pH of the mobile phase was adjusted to 3.4 with ortho-phosphoric acid and pumped at a flow rate of 1 mL/min using isocratic pump system. Multivariate chromatographic calibration technique was subjected to high-performance liquid chromatography (HPLC) data for simultaneous quantitative analysis of binary mixtures of clopidogrel and aspirin. HPLC data based on the analyte peak areas were obtained at five wavelengths (225, 230, 235, 240, and 245 nm). The mathematical algorithm of multivariate chromatographic calibration technique is based on the use of the linear regression equations. Calibration plots for clopidogrel and aspirin were constructed at each wavelength by using the peak areas corresponding to the concentrations of each active compound. This multivariate chromatographic method was also applied to a commercial pharmaceutical dosage form containing clopidogrel and aspirin.

Synthesis, characterization and biological activity of a series of carboxamide derivatives of ofloxacin.

The present study was designed to help develop new agents with better antimicrobial profiles. Specifically, we focused on modification of the basic structure of ofloxacin by introducing new functionality at its C3 position. For this purpose, the carboxylic group at the C3 position of ofloxacin was replaced by an amide group through an ester aminolysis reaction. The structure of these derivatives was established by various analytical techniques i.e., IR, (1)H-NMR, (13)C-NMR CHNS elemental analysis and mass spectrometry. The antibacterial activity of ofloxacin and its derivatives against ten different Gram-positive and Gram-negative microorganisms was studied using a disk susceptibility method. These compounds were further tested for their activity against various fungi and compared to ofloxacin. The synthesized compounds showed diverse antimicrobial profiles. Among them, a few compounds possessed a comparable or better activity in comparison to the reference drug.

Simultaneous determination of piracetam and its four impurities by RP-HPLC with UV detection.

A simple and rapid high-performance liquid chromatographic method for the separation and determination of piracetam and its four impurities, 2-oxopyrrolidin-1-yl)acetic acid, pyrrolidin-2-one, methyl (2-oxopyrrolidin-1-yl)acetate, and ethyl (2-oxopyrrolidin-1-yl)acetate, was developed. The separation was achieved on a reversed-phase C(18) Nucleosil column (25 cm x 0.46 cm, 10 microm). The mobile phase is composed of an aqueous solution containing 0.2 g/L of triethyl amine-acetonitrile (85:15, v/v). The pH of the mobile phase was adjusted to 6.5 with phosphoric acid at a flow rate of 1 mL/min at ambient temperature and UV detection at 205 nm. The developed method was found to give good separation between the pure drug and its four related substance. The polynomial regression data for the calibration plots showed good linear relationship in the concentration range of 50-10,000 ng/mL, 25-10,000 ng/mL, 45-10,000 ng/mL, 34-10,000 ng/mL, and 55-10,000 ng/mL, respectively, with r(2) = 0.9999. The method was validated for precision, accuracy, ruggedness, and recovery. The minimum quantifiable amounts were found to be 50 ng/mL of piracetam, 25 ng/mL of 2-oxopyrrolidin-1-yl)acetic acid, 45 ng/mL of pyrrolidin-2-one, 34 ng/mL of methyl (2-oxopyrrolidin-1-yl)acetate, and 55 ng/mL of ethyl (2-oxopyrrolidin-1-yl)acetate. Statistical analysis proves that the method is reproducible and selective for the estimation of piracetam as well as its related substance. As the method could effectively separate the drug from the related substances, it can be employed as a stability-indicating one. The proposed method shows high efficiency, allowing the separation of the main component piracetam from other impurities.

Simultaneous determination of metformin, cimetidine, famotidine, and ranitidine in human serum and dosage formulations using HPLC with UV detection.

A new, simple, and reliable reversed-phase high-performance liquid chromatographic method has been developed and validated for the simultaneous determination of metformin (Metf), cimetidine (Cimt), famotidine (Famt), and ranitidine (Rant) in their synthetic mixtures and tablet formulations. These drugs were separated on a Purospher Star RP18 endcapped (250 mm × 4.6 mm i.d.) column packed with 5-µm particles. The mobile phase, optimized through an experimental design, consisted of methanol-water-triethylamine (20:80:0.05), whose pH was adjusted to 3.0 with phosphoric acid (85%) pumped at a flow rate of 1.0 mL/min. UV detection was performed at 229 nm. The method was validated in the sample concentration range of 5-25 µg/mL for all the drugs, where it demonstrated good linearity with r = 0.9998, 0.9979, 0.9997, and 0.9987 (n = 6), respectively. For independent 100% level samples, the intra-day and inter-day precision was in the range i.e. < 2.0 for all the drugs. The method demonstrated robustness, resisting to small deliberate changes in pH, flow rate, and composition (organic:aqueous ratio) of the mobile phase. The limit of detection values were 0.071, 0.116, 0.134, and 0.110 µg/mL, while the limit of quantitation were 0.217, 0.352, 0.405, and 0.368 µg/mL for Metf, Cimt, Famt, and Rant, respectively. The applicability of the method was demonstrated by determining the drug content in pharmaceutical formulations, where it exhibited good performance.

Simultaneous determination of gliquidone, fexofenadine, buclizine, and levocetirizine in dosage formulation and human serum by RP-HPLC.

In the present paper, a simultaneous method has been developed and validated for estimation of gliquidone in the presence of H(1)-receptor antagonists (fexofenadine hydrochloride, buclizine hydrochloride, and levocetirizine dihydrochloride) using reversed-phase high-performance liquid chromatographic technique. A good chromatographic separation between these drugs was achieved using a mobile phase containing methanol-water (80:20 v/v) at pH 3.5 with a flow rate of 1.0 mL/min; and detection was performed at 230 nm with a UV detector. Validation of the method was performed in terms of linearity, accuracy, precision, and limit of detection and quantification. The linearity of the calibration curves for gliquidone, fexofenadine hydrochloride, buclizine hydrochloride, and levocetirizine dihydrochloride were found to be 0.338-50 microg/mL (r = 0.9964), 5-50 microg/mL (r = 0.9956), 0.325-50 microg/mL (r = 0.9967), and 0.553-50 microg/mL (r = 0.9950), respectively. There was no significant difference between the amount of drug spiked in serum and the amount recovered, and serum did not interfere in simultaneous estimation. Thus, the proposed method is suitable for the simultaneous analysis of active ingredients in tablet dosage forms and human serum.

Spectrophotometric determination of gabapentin in pharmaceutical formulations using ninhydrin and pi-acceptors.

Simple, rapid and sensitive spectrophotometric procedures are developed for the analysis of gabapentin in pure form as well as in their pharmaceutical formulations. The methods are based on the reaction of gabapentin as n-electron donor with ninhydrin and pi-acceptors namely, 2,3,5,6-tetrachloro-1,4-benzoquinone, chloranilic acid, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, tetracyanoethylene and 7,7,8,8-tetracyanoquinodimethane. The obtained complexes were measured at 568, 230, 314, 304, 335 and 439 nm for ninhydrin, chloranil, Chloranilic acid, DDQ, TCNE and TCNQ respectively. The proposed procedures could be successfully applied to the determination of gabepentin with good recovery; percent ranged from 99.3 to 100.7 The association constants and free energy changes using Benesi-Hildebrand plots are also studied.