Solvent effect on the vibrational spectra of Carvedilol (original) (raw)
Related papers
Study of carvedilol by combined Raman spectroscopy and ab initio MO calculations
2002
The novel cardioprotective drug carvedilol was studied by both Raman spectroscopy and ab initio molecular orbital methods (using the density functional theory approach). The spectra, acquired both for the solid samples and DMSO solutions as a function of pH, were assigned in view of the calculated wavenumbers and intensities, and also based on the experimental data obtained for individual compounds which comprise the molecule, namely carbazole and 1,2-dimethoxybenzene. The pH dependence of the Raman pattern of carvedilol was studied, and the pK a value of its secondary amine group was determined (pK a = 8.25) through pH titration experiments. This kind of information is of great significance for the understanding of the biochemical role of carvedilol, which is strongly determined by the acid-base behaviour of the molecule.
Simple Methods for the Spectrophotometric Determination of Carvedilol
ISRN Spectroscopy, 2012
Two simple spectrophotometric methods are described for the determination of carvedilol (CAR). Method A is the condensation reaction of CAR with p-dimethylaminobenzaldehyde (PDAB), and the reaction mixture exhibits maximum absorbance at 601 nm. Method B is based on the charge transfer complex formation of CAR with p-chloranil; the color developed is measured at 662 nm. The calibration graphs are found to be linear over 50.00–250.00 and 20.00–100.0 μg mL−1 with molar absorptivity values of 0.92×103 and 0.257×104 L mol−1cm−1 for CAR-PDAB and CAR-p-chloranil, respectively. Statistical comparisons of the results are performed with regard to accuracy and precision using Student’s t-test and F-test at 95% confidence level. The methods are successfully employed for the determination of CAR in pharmaceutical preparations, and the results agree favorably with the reference and proposed methods.
Pharmaceutical Salts of Carvedilol: Polymorphism and Physicochemical Properties
We report novel pharmaceutical salts of an anti-hypertensive drug carvedilol (CVD) with pharmaceutically acceptable salt formers, including oxalic acid (OXA), fumaric acid (FUMA), benzoic acid (BZA), and mandelic acid (MDA) via conventional solvent evaporation technique. The pKa difference between CVD and selected acids was greater than 3, thus suggesting salt formation. Two polymorphic forms of CVD/MDA salts and one p-Dioxane solvate of CVD/FUMA salt were also reported in this paper. The salts were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Stability of the salts was assessed by storage at 40°C/ 75% RH for 1 month. All CVD salts exhibited higher solubility in phosphate buffer solution pH 6.8 compared to the parent drug CVD and showed good stability in accelerated ICH conditions at 40°C/75% RH for 1 month. CVD/FUMA salt showed the highest solubility (1.78 times). Based on thermal analysis and slurry experiment, it was found that CVD/MDA polymorphs were related monotropically with Form 1 as the stable form. The results suggested that salt formation could be an alternative method to improve CVD solubility.
Spectrophotometric Estimation of Carvedilol via Schiff̕ s base Reaction with 4-Hydroxybenzaldehyde
Egyptian Journal of Chemistry, 2021
Simple, sensitive, precise, and accurate spectrophotometric method was suggested for the estimation of carvedilol (CARVL) as pure, and in it is formulation. The method is based on Schiff base reaction included condensation of CARVL with 4-hydroxybenzaldehyde(4-HBED) and 0.5 ml of concentrated sulphuric acid was added . All parameters that affected the formation of the product have been studied and the optimal was selected. The colored Schiff base product gave maximum absorption at 533 nm. The linearity of the method was obeyed Beer’s law in the concentration range of 0.5 to 5 µg/ ml, with a molar absorptivity of 8.463 ×104 L mol-1 cm-1. The suggested method was applied to the determination of CARVL in Tablet formulations with accepted results of recovery of CARVL from it is drugs without any interfering of the common excipients.
doiserbia.nb.rs
A sensitive, simple and selective spectrofluorimetric method was developed for the determination of carvedilol (CA) in pharmaceutical formulation and a biological fluid. The method is based on the reaction between the drug and 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) in the presence of mixture (acetone:0.5 M sodium carbonate, 3:2) at pH 10 to yield a highly fluorescent derivative that is measured at 445 nm after excitation at 350 nm. Different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence concentration plot was rectilinear over the range of 5.0-80.0 ng ml-1 with a lower detection limit (LOD) of 1.90 ng ml-1 and the limit of quantitation (LOQ) of 5.15 ng ml-1. Quantum yield, formation constant (K) and free energy change (ΔG) values were calculated. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official titrimetric method [1,2]. Furthermore, the method was applied for the determination of CA in spiked human plasma, the mean % recovery (n = 5) is 97.82±0.373. A proposal of the reaction pathway was presented.
Journal of The Serbian Chemical Society, 2007
A sensitive, selective, precise and stability-indicating, new high-performance liquid chromatographic method for the analysis of carvedilol both as a bulk drug and in formulations was developed and validated. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. The method was validated for linearity, selectivity, precision, robustness, LOD, LOQ and accuracy. The chromatographic separation was achieved on a Chromolit RP 8e, 100´4.6 mm, analytical column. The mobile phase consisted of a mixture of acetonitrile and water (45:55, V/V) (pH 2.5), pH adjusted with formic acid. The absorbance was monitored with a UV detector at 280 nm and the temperature of the analyses was 40°C. The flow rate was 0.5 mL/min. The linearity (r ³ 0.999), reproducibility (0.68-1.27 %) and recovery (99.71-101.58) were found to be satisfactory. This method enables the simultaneous determination of carvedilol and its degradation products, as well as stability.
Journal of Luminescence, 2016
Carvedilol (CAR) binding to human and bovine serum albumins (HSA and BSA) was studied using fluorescence, UV-vis absorption and Fourier transform infrared spectroscopy (FTIR) and molecular docking techniques at different temperatures (288,298 and 308 K) under physiologic pH. Results obtained from fluorescence data indicated that values of binding sites (n), effective quenching constants (Ka) and binding constants (K b) decreased under higher temperature and that the quenching mechanism was static. The thermodynamic parameters including enthalpy (ΔH), entropy (ΔS) and Gibbʼs free energy (ΔG) changes were calculated by the van , t Hoff equation and these data showed that hydrogen bonds and Van der Waals contacts were the main binding force in HSA-CAR and BSA-CAR systems. Binding distance (r) between HSA-CAR and BSA-CAR were calculated by the Fӧrster (fluorescence resonance energy transfer (FRET)) method. FTIR absorption studies showed that the secondary structure was changed according to the interaction of HSA/BSA and CAR. Results determined by molecular docking were in agreement with thermodynamic and FRET data and confirmed that the binding mechanism of Carvedilol to HSA and BSA is different.
SPECTROPHOTOMETRIC QUANTIFICATION OF CARVEDILOL IN BULK DRUG AND TABLETS
Hydrotropic solubilization technique is used to increase aqueous solubilities of poorly water soluble drugs using hydrotropic agents. In the present investigation hydrotropic solution of sodium benzoate (2M) has been used as a solubilizing agent to solubilize poorly water soluble drug. Etoricoxib shows maximum absorbance at 282 nm. Beer's law was obeyed in the concentration range of 5-20 μg /ml. Results of analysis were validated statistically and by recovery studies. The proposed method is now simple, new, environmentally friendly, and accurate, cost-effictive and successfully employed in routine analysis of etoricoxib bulk drug and tablet dosage forms. Hydrotropic agent sodium benzoate did not interfere in spectrophotometric determination.
Journal of Pharmaceutical Sciences, 2016
The experiments of carvedilol form II, form III, and hydrate by 13 C and 15 N cross-polarization magic-angle spinning (CP MAS) are reported. The GIPAW (gauge-including projector-augmented wave) method from DFT (density functional theory) calculations was used to simulate 13 C and 15 N chemical shifts. A very good agreement was found for the comparison between the global results of experimental and calculated nuclear magnetic resonance (NMR) chemical shifts for carvedilol polymorphs. This work aims a comprehensive understanding of carvedilol crystalline forms employing solution and solid-state NMR as well as DFT calculations.