Biomedical subjects

S Agatonovic-Kustrin

Publications and source records attributed to S Agatonovic-Kustrin.

23 records · Page 2Linked to original sources

PubMed1999

Solid state assay of ranitidine HCl as a bulk drug and as active ingredient in tablets using DRIFT spectroscopy with artificial neural networks.

PURPOSE: A new, simple, sensitive and rapid method was developed to analyse the polymorphic purity of crystalline ranitidine-HCI as a bulk drug and from a tablet formulation. METHODS: Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was combined with Artificial Neural Networks (ANNs) as a data modelling tool. A standard feed-forward network, with backpropagation rule and with single hidden layer architecture was chosen. Reduction and transformation of the spectral data enhanced the ANN performance and reduced the complexity of the ANNs model. Spectral intensities from 1738 wavenumbers were reduced into 173 averaged spectral values. These 173 values were used as inputs for the ANN. Following a sensitivity analysis the number of inputs was reduced to 30, or 35, these being the input windows which had most effect on the output of the ANN. RESULTS: For the bulk drug assay, the ANN model had 30 inputs selected from a sensitivity analysis, one hidden layer, and two output neurons, one for the percentage of each ranitidine hydrochloride crystal form. The model could simultaneously distinguish between crystal forms and quantify them enabling the physical purity of the bulk drug to be checked. For the tablet assay, the ANN model had 173 averaged spectral values as the inputs, one hidden layer and five output neurons, two for the percentage of the two ranitidine hydrochloride crystal forms and three more outputs for tablet excipients and additives. The ANN was able to solve the problem of overlapping peaks and it successfully identified and quantified all components in tablet formulation with reasonable accuracy. CONCLUSIONS: Some of the advantages over conventional analytical methods include simplicity, speed and good selectivity. The results from DRIFT spectral quantification study show the benefits of the neural network approach in analysing spectral data.

Anti-Ulcer Agents↗

PubMed1998

Application of artificial neural networks in HPLC method development.

The use of artificial neural networks (ANNs) for response surface modelling in HPLC method development for amiloride and methychlothiazide separation is reported. The independent input variables were pH and methanol percentage in mobile phase. The outputs were capacity factors. The results were compared with a statistical method (multiple nonlinear regression analysis). Networks were able to predict the experimental responses more accurately than the regression analysis.

Amiloride↗

PubMed1996

Comparison of high-performance and thin-layer chromatographic methods for the assay of lidocaine.

Reversed-phase high-performance liquid chromatographic (HPLC) and thin-layer chromatographic (TLC)-UV densitometric methods were developed for the quality control of lidocaine hydrochloride bulk drug and its injection solutions. The HPLC method used an RP-18 reversed-phase column with methanol-water-1% phosphoric acid-hexylamine (30:70:100:1.4, v/v/v/v) as the mobile phase and detection at 254 nm, with a capacity factor k' = 0.8. The TLC-UV densitometric method was performed on silica gel plates using diisopropyl ether-acetone-diethylamine (85:10:5, v/v/v) as the developing solvent and UV detection at 254 nm. The response was linear up to 10 micrograms ml-1 (HPLC) and 8 mg ml-1 (TLC). The RSD of the peak areas was 1.71% for HPLC and 0.55% for TLC, with recoveries in the range 99.6-100.2% for HPLC and 99.2-100.7% for TLC.

Chromatography, High Pressure Liquid↗

PubMed1992

Investigation of Fe(III) chloride as a colour reagent for the spectrophotometric determination of bumetanide in the pure form and in preparations.

The formation and stability of the complex between bumetanide (3-butylamino-4-phenoxy-5-sulphamoylbenzoic acid) and Fe(III) ion was studied. It has been found that bumetanide reacts with Fe(III) chloride in the presence of ammonium thiocyanate at the pH 1.83-1.92 to form a violet complex soluble in chlorophorm, with the maximum absorbance at 514.5 nm. At the optimum experimental conditions the conditional stability constant of the complex was found to be log K' = 7.34. The Beer's law was obeyed up to the 160 microg x cm(-3) and the relative standard deviation varied from 0.406% to 0.475% (n = 10). The proposed method was found to be suitable for the accurate and sensitive analysis of bumetanide as a pure compound and from tables and ampoules.

Bumetanide↗

PubMed1989

Spectrophotometric study of polythiazide-palladium (II) complex.

A quantitative spectrophotometric method using Pd(II) chloride as analytical reagent for the determination of polythiazide in pharmaceutical preparations is described in this study. It has been found that polythiazide reacts with Pd(II) chloride in the pH range 3.6-5.8, forming a red, water-soluble (1:1) complex with maximum absorbance at 527 nm. At the optimum pH of 4.8 and an ionic strength mu = 0.1 M, the conditional stability constant of the complex is found to be log K' = 4.77. The molar absorptivity at 527 nm is 3.2 x 10(3) l mol-1 cm-1. Good agreement with Beer's law was found for polythiazide concentrations up to 2.2 mmol l-1. The nominal percent recovery of polythiazide was 99.5% (n = 20). The simplicity, selectivity and sensitivity of the method described is suitable for rapid and accurate determinations of polythiazide in tablets.

Drug Stability↗