Synthesis and antibacterial activity of 2-phenyl-3,5-diphenyl (substituted) -6-aryl-3,3a,5,6-tetrahydro-2h-pyrazolo[3,4-d]thiazoles

Simultaneous evaluation of losartan and amlodipine besylate using second-derivative synchronous spectrofluorimetric technique and liquid chromatography with time-programmed fluorimetric detection

This study is concerned with two sensitive, fast and reproducible approaches; namely, second-derivative synchronous fluorimetry (method I) and reversed phase high-performance liquid chromatography with fluorimetric detection (method II) for synchronized evaluation of losartan (LOS) and amlodipine besylate (AML). Method I is based on measuring second-derivative synchronous fluorescence spectra of LOS and AML at Δλ = 80 nm in water. The experimental factors influencing the synchronous fluorescence of the considered compounds were sensibly adjusted. The chromatographic analysis was executed on a Nucleodur MN-C18 column of dimensions; 250 × 4.6 mm i.d. and 5 µm particle size). The fluorimetric detection was time-programmed at λem = 440 nm for AML (0.0-7.5 min) and at λem = 400 nm for LOS (7.5-10 min) after excitation at λex = 245 nm. The mobile phase is a blend of acetonitrile with 0.02 M phosphate buffer in a proportion of 45 : 55, pH 4.0, pumped using a flow rate of 1 ml min^-1. The calibration plots were established to be 0.1-4.0 µg ml^-1 for both drugs in method I and 0.05-4.0 µg ml^-1 for both drugs in method II. The study was extended to the evaluation of the two drugs in their co-formulated tablets.

Novel pure component contribution, mean centering of ratio spectra and factor based algorithms for simultaneous resolution and quantification of overlapped spectral signals: An application to recently co-formulated tablets of chlorzoxazone, aceclofenac and paracetamol

In this work, resolution and quantitation of spectral signals are achieved by several univariate and multivariate techniques. The novel pure component contribution algorithm (PCCA) along with mean centering of ratio spectra (MCR) and the factor based partial least squares (PLS) algorithms were developed for simultaneous determination of chlorzoxazone (CXZ), aceclofenac (ACF) and paracetamol (PAR) in their pure form and recently co-formulated tablets. The PCCA method allows the determination of each drug at its λmax. While, the mean centered values at 230, 302 and 253nm, were used for quantification of CXZ, ACF and PAR, respectively, by MCR method. Partial least-squares (PLS) algorithm was applied as a multivariate calibration method. The three methods were successfully applied for determination of CXZ, ACF and PAR in pure form and tablets. Good linear relationships were obtained in the ranges of 2-50, 2-40 and 2-30μgmL(-1) for CXZ, ACF and PAR, in order, by both PCCA and MCR, while the PLS model was built for the three compounds each in the range of 2-10μgmL(-1). The results obtained from the proposed methods were statistically compared with a reported one. PCCA and MCR methods were validated according to ICH guidelines, while PLS method was validated by both cross validation and an independent data set. They are found suitable for the determination of the studied drugs in bulk powder and tablets.

Density functional theory study on characterization of 3-chloro-1,2-benzisothiazole

The FT-IR and FT-Raman spectra of 3-chloro-1,2-benzisothiazole (CBT) have been recorded and analyzed. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations, using 6-311++G(d,p) basis set. Mulliken population analysis shows charge distribution on the molecule. Thermodynamic properties like entropy, heat capacity, zero point energy have been calculated for the molecule. The calculated HOMO and LUMO energies show the charge transfer occurs within the molecule. Stability of the molecule has been analyzed using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. The results of the calculations were applied to simulated spectra of the title compound, which show the excellent agreement with the observed spectra.

Three different spectrophotometric methods manipulating ratio spectra for determination of binary mixture of Amlodipine and Atorvastatin

Three simple, specific, accurate and precise spectrophotometric methods manipulating ratio spectra are developed for the simultaneous determination of Amlodipine besylate (AM) and Atorvastatin calcium (AT) in tablet dosage forms. The first method is first derivative of the ratio spectra ((1)DD), the second is ratio subtraction and the third is the method of mean centering of ratio spectra. The calibration curve is linear over the concentration range of 3-40 and 8-32 μg/ml for AM and AT, respectively. These methods are tested by analyzing synthetic mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is <1.5 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit.