Polymer membrane sensors for sildenafil citrate (Viagra) determination in pharmaceutical preparations

Othman, Abdelhameed M.; Rizk, Nashwa M. H.; El-Shahawi, M.S.

doi:10.1016/j.aca.2004.01.016

Cited by 46 publications

(21 citation statements)

References 16 publications

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“…So far, numerous analytical methods for the determination of sildenafil in pharmaceutical formulations have been proposed including highperformance liquid chromatography (HPLC) with UV [2 -6] or mass spectrometry [4,6,7] (MS) detection, capillary gas chromatography, [8] spectrophotometric methods, [9] infrared spectroscopy [10] (IR), polymer membrane sensors, [11] micellar electrokinetic capillary chromatography, [12] thin-layer chromatography [4] (TLC) and highperformance TLC. [13,14] All these methods focus on the active pharmaceutical ingredient sildenafil and do not provide any other information on the pharmaceutical formulation.…”

Section: Introductionmentioning

confidence: 99%

The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

Trefi

Gilard

Balayssac

et al. 2009

Magnetic Reson in Chemistry

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Two-dimensional diffusion ordered spectroscopy (DOSY) (1)H NMR is proposed to analyze drugs that are complex mixtures in order to discriminate genuine from fake formulations. The method was applied to the analysis of 17 formulations of sildenafil, one being genuine Viagra and the others illegally manufactured formulations of this drug coming from India, Syria and China. It enabled (i) distinguishing imitations or counterfeit from the authentic formulation, (ii) detecting the presence of sildenafil or adulterants, (iii) gaining information on the formulation process by detection of various excipients, thus giving a precise and global 'signature' of the manufacturer. Even though some samples are slightly overdosed, the quality of products manufactured in India and Syria was better than that of Chinese formulations which were adulterated with vardenafil and homosildenafil. This study also presents a three-dimensional DOSY-COSY (1)H NMR experiment that provides both virtual separation and structural information.

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Section: Introductionmentioning

confidence: 99%

The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

Trefi

Gilard

Balayssac

et al. 2009

Magnetic Reson in Chemistry

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“…The results show that the method for the determining of Slid has a higher sensitivity. For example, the sensitivity of the method is over 100-times that of potentiometry, 11 several times higher than that of flow injection analysis, 6 but approximate the same as that of HPLC. 7,8 Therefore, this method is suitable for determining trace levels of Slid.…”

Section: Calibration Graphmentioning

confidence: 99%

Resonance Rayleigh-Scattering Method for the Determination of Sildenafil Citrate in a Pharmaceutical Formulation Using Evans Blue

Liu¹,

Fan²,

Hu³

et al. 2006

ANAL. SCI.

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Sildenafil citrate is a potent and selective inhibitor of cGMP (type V)-specific phosphodiesterase capable of enhancing relaxation of the penile corpus cavernosum, and therefore having the potential to improve penile erectile function. 1 The activity of Sild is as an efficacious, orally active agent for the treatment of male erectile dysfunction, and is thus so currently being applied widely to clinical treatments. 2,3At present, most of the methods for the determination of Sild are based on HPLC, 4-9 and electrochemistry. 10,11 However, the procedures for many methods are not simple due to a preseparation required frequently before determining Sild; also, the sensitivity of some methods is not high enough. Dinesh et al. 12 reported an extractive spectrophotometric method for the determination of Sild with acid triphenylmethane dyes. The sensitivity of this method was insufficient and double extraction was required. Thus, further developing a highly sensitive, simple and rapid method for the determination of Sild is important.In recent years, resonance Rayleigh scattering (RRS) as a new analytical technique has been applied to investigate and determine some inorganic ions [13][14][15] and biological macromolecules, such as nucleic acid, 16-18 protein, 19-21 heparin 22,23 and medicines. [24][25][26][27][28] In this work, we found that in a weak acid aqueous solution, the RRS for Sild alone as an organic cation or Evans Blue (EB), itself, as an organic anion was weak. However, when two agents reacted with each other to form ion-association complexes by virtue of electrostatic and hydrophobic interaction forces, the RRS intensity could be greatly enhanced and a new RRS spectrum was observed. The intensity of RRS was directly proportional to the concentration of Sild in the range 0 -11.5 μg ml -1 . The method had high sensitivity and the detection limit for the sild was 30.3 ng ml -1 . In the present work, the spectral characteristics of RRS, the influence of various factors, optimum conditions of interaction, and the properties of analytical chemistry were investigated. A new method for the determination of Sild in a pharmaceutical formulation based on the RRS of the ion-association complex has been developed. Furthermore, the interaction mechanism was considered. Experimental Apparatus and reagentsA Shimadzu RF-540 Fluorospectrophotometer (Kyoto, Japan) was used for recording the RRS spectrum. A UV-VIS 8500 spectrophotometer (Tianmei Co., Shanghai, China) was used for recording the absorption spectrum. A pHs-3C acidimeter (Shanghai Dazhong Analytical Instrumental Plant, China) was used for adjusting of the pH value.A 1.0 × 10 -3 mol l -1 stock solution of Sild (offered by West China College of Medicine, Sichuan University, purity 99.9%) was prepared using water and the dilution was made to the 66.6 μg ml -1 working solution. EB (Fluka Co., Switzerland) aqueous A highly sensitive resonance Rayleigh-scattering (RRS) method for the determination of sildenafil citrate has been developed, based on the fact that sild...

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“…The approach provides simple, fast, and selective technique for determination of various drugs [10][11][12][13][14][15][16][17]. However, as far as the available literature is concerned, very little is known about the use of this technique for viagra quantification [18].…”

Section: Introductionmentioning

confidence: 99%

Continuous potentiometric monitoring of viagra (sildenafil) in pharmaceutical preparations using novel membrane sensors

et al. 2005

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Two potentiometric sensors responsive to sildenafil citrate (SC) drug (the active component of viagra) are described, characterized, compared and used for drug assessment. The sensors are based on the use of the ion-association complexes of (SC) cation with tungstophosphate (TP) and reineckate (Re) anions as electroactive materials in plasticized poly(vinyl chloride) membranes. The sensors demonstrate fast near-Nernstian response for SC over the concentration ranges 1.0Â10 )2 -7.9Â10 )7 and 1.0Â10 )2 -1.0Â10 )6 M with detection limits of 0.53 and 0.67 lg ml )1 over pH 3-6 for TP and Re based membrane sensors, respectively. The sensors display good selectivity for SC drug over many nitrogeneous compounds, some inorganic cations and excipients and diluents commonly used in drug formulations. Validation of the assay methods with both sensors by measuring the lower detection limit, range, accuracy, precision, repeatability and between-day-variability reveals good performance characteristics confirming applicability for continuous determination of SC in pharmaceutical formulations and in spiked human serum. A membrane incorporating SC-TP complex in a tubular flow detector is used in a two channel flow injection set up for continuous monitoring of the drug at a frequency of 25-30 samples h )1 . The results obtained with drugs containing 50-100 mg SC tablet )1 show a mean standard deviation of ±2% of the nominal which agree fairly well with data obtained by spectrophotometry.

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Polymer membrane sensors for sildenafil citrate (Viagra) determination in pharmaceutical preparations

Cited by 46 publications

References 16 publications

The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

Resonance Rayleigh-Scattering Method for the Determination of Sildenafil Citrate in a Pharmaceutical Formulation Using Evans Blue

Continuous potentiometric monitoring of viagra (sildenafil) in pharmaceutical preparations using novel membrane sensors

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Polymer membrane sensors for sildenafil citrate (Viagra) determination in pharmaceutical preparations

Cited by 46 publications

References 16 publications

The usefulness of 2D DOSY and 3D DOSY‐COSY 1H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

The usefulness of 2D DOSY and 3D DOSY‐COSY 1H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

Resonance Rayleigh-Scattering Method for the Determination of Sildenafil Citrate in a Pharmaceutical Formulation Using Evans Blue

Continuous potentiometric monitoring of viagra (sildenafil) in pharmaceutical preparations using novel membrane sensors

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The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)

The usefulness of 2D DOSY and 3D DOSY‐COSY ¹H NMR for mixture analysis: application to genuine and fake formulations of sildenafil (Viagra)