Biomedical subjects

E Dinç

Publications and source records attributed to E Dinç.

10 recordsLinked to original sources

PubMed2005

Comparative application of wavelet approaches to absorption and ratio spectra for the simultaneous determination of diminazene aceturate and phenazone in veterinary granules for injection.

A comparison of two wavelet approaches, Daubechies and reverse Biorthogonal, is described for the quantitative resolution of a binary mixture of diminazene aceturate (DIMA) and phenazone (PHE) in veterinary granules for injection without any chemical separation. These two approaches were specified as db4 (a = 180) and rbior3.7 (a = 125) respectively, after testing the signal analysis parameters for the overlapping absorption spectra and ratio spectra. In the first step db4 (a = 180) was applied to the original absorbance data vector of DIMA and PHE. In the second step rbio3.7 (a = 125) was applied to the ratio spectra data vectors of DIMA using the divisor PHE. The same approach was also subjected to the ratio spectra of PHE using the divisor DIMA. The db4 (a = 180) and rbior3.7 (a = 125) calibration graphs were constructed using the transformation values obtained in the wavelet domain. In the method validation, the wavelet calibration functions were tested using synthetic mixtures and the standard addition technique. The simultaneous quantitative analysis of DIMA and PHE in the commercial veterinary preparation was achieved by the elaborated methods. The assay results were compared with each other and good agreement was observed.

Algorithms↗

PubMed2004

Continuous wavelet transformation applied to the simultaneous quantitative analysis of two-component mixtures.

In this paper we developed a graphical method based on Haar (HA) and Mexican (MEX) one-dimensional continuous wavelet transforms and we applied it to a mixture of hydrochlorothiazide (HCT) and spironolactone (SP) in the presence of strongly overlapping signals. Keeping in mind to obtain an appropriately transformed spectrum, we tested several values of the scaling parameter a and the point number of the analysed spectrum in the concentration range of 2-22 microg/ml for both active compounds. The optimal values of the scale parameters and the corresponding frequencies were found to be a = 32 and 0.031 for HA and a = 30 and 0.008 for MEX corresponding to 400 points. HA and MEX methods based on a zero crossing technique were applied to the analysed signal and their regression lines at the selected points were obtained. The validation of the above methods was carried out by analysing different synthetic mixtures containing HCT and SP. MATLAB 6.5 software was used for one-dimensional wavelet analysis and the basic concepts about wavelet method were briefly explained. The method developed in this paper is rapid, easy to apply, inexpensive and is suitable for analysing the overlapping signals of compounds in their mixtures without any chemical pre-treatment.

Algorithms↗

PubMed2004

Multivariate spectral calibration technique based on regression analysis for the quantitative multiresolution of a ternary mixture containing paracetamol, ascorbic acid and acetylsalicylic acid in effervescent tablets.

Multivariate spectral calibration techniques based on regression analysis were established for the quantitative multiresolution of a ternary mixture containing parecetamol (PAR) ascorbic acid (AA) and acetylsalicylic acid (ASP) having closely overlapping spectra. The mathematical algorithms of multivariate spectral calibrations as namely tri-linear regression calibration (TLRC) and multi-linear regression calibration (MLRC) are based on the use of the linear regression equations at a three-wavelength set and a ten-wavelength set in the range of 215-305 nm. These calibration techniques do not require any chemical pre-treatment and a graphical procedure of the overlapping spectra. The mathematical content of TLRC and MLRC approaches were briefly formulated for the quantitative analysis of three- or multi-component mixtures. The applicability of the formulated calibration models were tested by analysing the various synthetic ternary mixtures consisting of these active compounds and then these models were applied to real pharmaceutical formulations. It was observed that TLRC and MLRC models give a successful quantitative multiresolution. The experimental results of these techniques were compared with each other as well as with those obtained by literature methods.

Acetaminophen↗

PubMed2003

Dissolution and assaying of multicomponent tablets by chemometric methods using computer-aided spectrophotometer.

Dissolution of three component tablets containing paracetamol (APAP), propyphenazone (PP), and caffeine (CAF) was carried out by USP paddle method. Three chemometric methods; inverse least square (ILS), principal component regression (PCR) and partial least squares (PLS) were applied to simultaneous assay of APAP, PP and CAF in tablets. The PCR, PLS and ILS methods were applied to simultaneous dissolution APAP, PP and CAF in tablets using a double beam UV-Vis spectrophotometer without any chemical separation and any graphical treatment of the overlapping spectra of three drugs. Twenty two mixture solutions in different concentrations were prepared in simulated gastric juice (SGJ, USP) for the chemometric calibrations as training set. The absorbance data matrix was obtained by measuring the absorbance at 14 wavelength points (from 222.5 to 292.5 nm) with the intervals of 5 nm (Deltalambda=5 nm) in the spectral region between 200 and 310 nm. Training set and absorbance data were used for the calibrations of chemometric methods. The developed calibrations were tested for the previously prepared solutions of mixture of three drugs for the validation of the assay method. The chemometric calculations were performed by using the 'MAPLE VRSQUO; software. The results of three chemometric methods were statistically compared with each other. These chemometric calibrations were successfully applied to the content uniformity and dissolution of the multicomponent tablets without any separation procedure. The synthetic mixtures of three drugs were used for the validity of the calibrations. Means recoveries (percent) and relative standard deviation of PLS, PCR and ILS methods were found to be 100.1+/-0.6, 101.4+/-1.6 and 100.1+/-0.6 for APAP; 100.9+/-3.2, 102.0+/-3.3 and 100.9+/-3.2 for PP; 99.9+/-3.5, 101.6+/-3.3 and 99.9+/-3.2 for CAF, respectively. Dissolution profiles of three component tablets were performed. More than 95% of drugs were dissolved within 15 min. All of the three-chemometric methods in this study can be satisfactorily used for the quantitative analysis and for dissolutions test of multicomponent dosage form.

Numerical Analysis, Computer-Assisted↗

PubMed2003

Simultaneous resolution of a binary mixture of captopril and hydrochlorothiazide in tablets by bivariate and multivariate spectral calibrations.

The multivariate spectral calibration methods, two-linear regression-calibration (bivariate calibration (BC)) and multi-linear regression-calibration (MLRC) are proposed for the simultaneous resolution of a binary mixture of hydrochlorothiazide (HCT) and captopril (CTP), which have closely overlapping spectra. The BC and MLRC calibration algorithms are described for the two-component system, HCT-CTP. Some alternative methods, classical least squares (CLS), inverse least squares (ILS), principal component regression (PCR) and principal least squares (PLS) methods, were also used to determine HCT and CTP in the mixture. Using a synthetic mixture of the two drugs, all the methods were validated and applied to tablets. The BC and MLRC methods which are very rapid, and easy to apply, yet not expensive, are powerful tools with very simple mathematical contents for the quantitative analysis. Data treatment was performed using MAPLE V, EXCEL and SPSS 10.0 Software.

Algorithms↗

PubMed2002

Two new spectrophotometric approaches to the multicomponent analysis of the acetaminophen and caffeine in tablets by classical least-squares and principal component regression techniques.

Classical least-squares (CLS) and principal component regression (PCR) techniques were proposed for the simultaneous analysis of tablets containing acetaminophen and caffeine without using a chemical separation procedure. The chemometric calibrations were prepared by measuring the absorbances values at the 15 wavelengths in the spectral region 215-285 nm and by using a training set of the mixtures of both drugs in 0.1 M HCI. The obtained chemometric calibrations were used for the estimation of acetaminophen and caffeine in samples. The numerical calculations were performed with the 'MAPLE V' software. By applying two techniques to synthetic mixtures, the mean recoveries and the relative standard deviations in the CLS and PCR techniques were found as 99.5 and 1.29, 99.7 and 1.00% for acetaminophen and 99.9 and 1.92, 100.0 and 1.178% for caffeine, respectively. Our results were compared with those obtained previously by one of us considering HPLC method as a reference method. These two methods were successfully applied to a pharmaceutical tablet formulation of two drugs.

Acetaminophen↗

PubMed2001

Derivative ratio spectra-zero crossing spectrophotometry and LC method applied to the quantitative determination of paracetamol, propyphenazone and caffeine in ternary mixtures.

Two methods were used to determine paracetamol, caffeine and propyphenazon in ternary mixtures and tablets. Derivative ratio spectra-zero crossing procedure was based on the simultaneous use of the first derivative of ratio spectra and measurements of derivative ratio analytical signals corresponding to the zero crossing points of wavelengths. By using propyphenazon as a divisor, the amounts of paracetamol and caffeine in the ternary mixture were determined by measuring the first derivative ratio amplitudes at 242.8 nm (zero-crossing point for caffeine) and 251.2 and 273.8 nm (zero-crossing point for paracetamol) respectively. Also by using paracetamol as a divisor, the contents of propyhenazon and caffeine in the same ternary mixture were determined by measuring the first derivative ratio amplitudes at 244.8 and 276.9 nm (zero-crossing point for caffeine) and 250.6 and 274.0 nm (zero-crossing point for propyphenazon), respectively. For the HPLC procedure, a Nucleosil C18 column and a mobile phase consisted of water and methanol (20:80) were used to separate three compounds with cetrimide as an internal standard. The flow rate was 1.0-ml/min with an ultraviolet (UV) detection at 254 nm. Both methods were also applied to the determination of these three compounds in ternary mixtures and tablet formulation. The analytical results were quite good in all cases.

Acetaminophen↗

PubMed2001

Spectrophotometric multicomponent analysis of a mixture of metamizol, acetaminophen and caffeine in pharmaceutical formulations by two chemometric techniques.

Inverse least squares (ILS) and factor-based (principal component analysis (PCA)) techniques were proposed for the spectrophotometric multicomponent analysis of a ternary mixture consisting of metamizol, acetaminophen and caffeine, without prior separation. In these chemometric techniques, the measurements of the absorbance values were realized in the spectral range from 225 to 285 nm in the intervals of Deltalambda=5 nm at the 13 wavelengths in the zero-order spectra of the different ternary mixtures of these active ingredients in 0.1 M HCl. The prepared calibrations of both techniques using the absorbance data and concentration matrix data sets were used to predict the concentration of the unknown concentrations of metamizol acetaminophen and caffeine in their ternary mixture. The 'MAPLE V' software was used for the numerical calculations. Mean recoveries and relative standard deviations for ILS and PCA techniques were found to be 99.8 and 1.68%, 99.9 and 1.66% for caffeine, 99.8 and 1.84%, 100.4 and 2.85% for metamizol, and 99.7 and 1.04%, 99.6 and 1.34% for acetaminophen, respectively, for the first and second techniques. The techniques were successfully applied to two pharmaceutical formulations marketed in Turkey and results were compared with a new high-performance liquid chromatography method.

Acetaminophen↗

PubMed1999

A comparative study of the ratio spectra derivative spectrophotometry, Vierordt's method and high-performance liquid chromatography applied to the simultaneous analysis of caffeine and paracetamol in tablets.

Two spectrophotometric methods and high-performance liquid chromatography were proposed for the simultaneous analysis of caffeine and paracetamol in a tablet formulation. The ratio spectra derivative method is based on the use of the analytical signals obtained by measuring at 267.9 and 291.0 nm for caffeine and 237.0 and 251.8 nm for paracetamol in the first derivative of the ratio spectra. Calibration graphs were prepared in the range 4-40 microg/ml for caffeine and 8-48 microg/ml for paracetamol. In Vierordt's method, A1(1) (1%, 1cm) values of paracetamol and caffeine were determined at 242.9 and 273.0 nm in zero-order spectra. The matrix for A1(1) (1%, 1cm) values was written and the amounts of both drugs were calculated by means of the program 'Matlab' software. The results obtained by these spectrophotometric methods were compared with the results of HPLC method.

Acetaminophen↗

PubMed1998

Influence of swelling degree on release of nicardipine hydrochloride from acrylic microspheres prepared by solvent evaporation method.

The purpose of this study was to prepare and evaluate an enteric coated dosage form of nicardipine hydrochloride (NCH)-loaded microspheres for delivery over a 12-hr period. Microspheres containing Eudragit RS and L with different ratios were prepared by solvent evaporation method and the effect of swelling on the release rate and characteristics was investigated. The change in the diameters of microspheres with time in simulated intestinal fluid (pH 7.5) at 37 degrees C has been studied. Drug release was determined using the flow-through cell method, and related to the degree of swelling (Q) of the microspheres. Q values in turn depended on the ratio of Eudragit RS-L used. Release of NCH from microspheres increased with Eudragit L amount, but no controlled-release pattern was observed. Q values > or = 18.88 caused a slow initial release followed by an accelerated release. Microspheres with an Eudragit RS-L ratio of 1:5.7, Q value of 38.71, and drug release rate of 0.155% min-1 exhibited a remarkable delayed time for erosion to begin (120 min). Thus, microspheres prepared from this formulation may provide an effective enteric dosage form, releasing NCH at a predetermined rate.

Acrylic Resins↗