Theses(P)

Permanent URI for this collectionhttps://dspace.tbzmed.ac.ir/handle/123456789/6

Browse

Filter results by typing the first few letters
Now showing 1 - 4 of 4
  • Thumbnail Image
    Item type: Item ,
    Determination of dissociation constant of naproxen in different solvent mixtures
    (Tabriz University of Medical Sciences, Faculty of Pharmacy, 2020) Asadi Ghorbani, Mahya; Mirzaei, Zeinab; Jouyban, Abolghasem; Khandar, Aliakbar
    Introduction: The dissociation constant is an important parameter in determining the behavior of compounds in various applications. Simplicity, accuracy and reproducibility of potentiometry made this method as an accepted technique for determination of dissociation constants among different methods. Aim: The aim of this project was to determine the dissociation constant of naproxen in mixtures of 1-propanol + water, 2-propanol + water and tetrahydrofuran + water in various concentrations of (10-90), (20-80), (30-70), (40-60), (50-50), (60-40), (70-30) and (80-20)% v/v at four temperatures of 298, 303, 308 and 313 K by potentiometry method using the BEST computer program. Methods: The ionic strength of solution was adjusted using potassium chloride at 0.1 mol.L-1. Naproxen titrations in different mixtures: 1-propaneol + water, 2-propaneol + water and tetrahydrofuran + water at four different temperatures of 298, 303, 308 and 313 K were done as described by Martell and Motekaitis. In order to the evaluation of the dissociation constant of naproxen, eight sample solutions in different binary solvent mixtures from 10 to 80% (v/v) were used in and the pH range of 2–12 adjusted with HCl of 0.001 mol.L-1. Results: The results showed that in different mixtures of solvents, the dissociation constant of naproxen increased with increasing the amount of organic solvent due to the dominance of the electrostatic forces in the equilibrium process and decreased by temperature increasing, because the acidity of naproxen decreases. Conclusion: The effect of temperature on the dissociation constant in three different temperatures was investigated and the related thermodynamic parameters of naproxen (ΔG°, ΔH° and ΔS°) were calculated from temperature dependence data.
  • Thumbnail Image
    Item type: Item ,
    Study of solubility and thermodynamic properties of amlodipine besylate in binary mixtures of n-methylpyrrolidone, 1-propanol, 2-propanol at different temperatures
    (Tabriz University of Medical Sciences, School of Pharmacy, 2025) Naghavi Kalajahi, Seyed Mahdi; Jouyban, Abolghasem; Rahimpour, Elaheh
    Introduction: Solubility data has extensive applications in various industries for purpose of dissolution, formulation, and crystallization processes. Various methods exist for altering drug solubility. Cosolvency is recognized as one of the simpler and more effective methods in this field. Objective: The aim of this research is to investigate the solubility and thermodynamic properties of amlodipine besylate in binary mixtures of (N-methylpyrrolidone + 1-propanol), and (N-methylpyrrolidone + 2-propanol) at different temperatures, and to predict solubility data using cosolvency models. Methods: In this study, the shake-flask method was employed for measurement of amlodipine besylate solubility in binary mixtures of solvents. In this process, an excess amount of the drug is added to vessels containing different compositions of solvents. After the solution reaches equilibrium at the specific temperature, the supernatant is separated from the remaining solid material using centrifugation or filtration. Then, after appropriate dilution, UV absorbance of the solution is measured at the drug's maximum wavelength, and the concentration of the samples are determined based on the calibration curve and dilution factors. Then, all acquired data are fitted to mathematical cosolvency models. The thermodynamic properties for dissolution and mixing are calculated using Gibbs and van’t Hoff equations. Results: The obtained data indicates that the solubility of amlodipine besylate increases with an increase in the mass fraction of the cosolvent (N-methylpyrrolidone) and with temperature increase. In both solvent-cosolvent systems, the highest solubility is observed in pure N-methylpyrrolidone at 313.2 K and, the lowest solubility in both systems is observed in pure 1-propanol and 2-propanol, respectively, at 298.2 K. Discussion and Conclusion: The present study demonstrated that with increasing temperature and increasing mass fraction of N-methylpyrrolidone, the dissolution of amlodipine besylate increases significantly. Additionally, the experimental data were compared with calculated data from various cosolvency models, and satisfactory results were obtained modeling accuracy.
  • Thumbnail Image
    Item type: Item ,
    Study on solubility of ketoconazole in binary mixtures of water and cosolvents
    (Tabriz University of Medical Sciences, Faculty of Pharmacy, 2020) Zad Ali Asghar, Samira; Rahimpour, Elaheh; Jouyban, Abolghasem; Shayanfar, Ali
    Drug solubility in water and organic solvents plays an important role in many pharmaceutical processes. Co-solvents such as organic solvents and ionic liquids have been widely used as effective and practical methods in the pharmaceutical industry for solubilization. In recent years, a new type of solvents named deep eutectic solvents (DESs) has been developed to be a useful solvent for drugs. Aim Investigation of the solubility of ketoconazole and some drugs (poorly soluble in water) in 2-propanol/PG + water and ChCl: Glycerol/Urea + water. Method The shake flask method was applied in this study. First, the solvent systems were prepared; then an excess amount of drugs was added into glassy vials containing binary solvent mixtures of cosolvent and water. Samples were placed in an incubator at specified temperatures to reach equilibrium. Then they were filtered/centrifuged and diluted with proper solvent mixture and were analyzed by spectrophotometer at specified lambda related to each drug. The concentrations of saturated mixtures were obtained using the calibration curve. The experimental data were fitted to some cosolvency models. Results The solubility data show the solubility of ketoconazole depends on temperatures and solvent composition. The solubility values rise by increasing temperatures and mass fraction of 2-propanol and PG. Furthermore, the results indicate all studied drugs have a significant enhancement in solubility in the presence of ChCl: Urea system as well as the highest solubility values are obtained in 50% mass fraction of ChCl: Urea. As well as, a good and meaningful correlation was obtained between the solubilization ratio and some structural descriptors of drugs. Conclusion 2-propanol and PG are good solubilization agents for enhancing the solubility of ketoconazole. Obtained MRD% values show that the Jouyban-Acree model has a good capability to predict the solubility of ketoconazole in two types of solvent mixtures at temperature ranges. In the other hand, the solubility of investigated drugs in aqueous solution of DES depends on various structural parameters and DES have an appropriate capacity to improve solubility of studied drugs.
  • Thumbnail Image
    Item type: Item ,
    Thermodynamic study of deferiprone dissolution in the binary system of 2-propanol and polyethylene glycol 400
    (Tabriz University of Medical Sciences , School of Pharmacy, 2023) Ahmadi, Mahsa; Jouyban, Abolghasem; Rahimpour, Elaheh
    Solubility data have many industrial applications and the change in solubility is used in dissolution, formulation and crystallization processes. There are various techniques to change the solubility of drugs, including cosolvency, particle size reduction, crystal engineering, salt formation, solid dispersion, surfactant use, and complex formation. Cosolvency is one of the simplest and best methods.Aim: Our aim is to investigate the thermodynamic solubility of deferiprone in PEG400 and 2-propanol solvent system and to predict the solubility data with cosolvency models.Method In this research, the shake-flask method was used to measure the solubility of deferiprone in PEG400 and 2-propanol solvent system. In this method, the excess amount of medicine is dispensed into containers with different mass ratios of cosolvent + solvent (11 fractions). After reaching the equilibrium of the solution at the set temperature, the supernatant solution is separated from the remaining solid material by centrifuge or filter, and after proper dilution, the absorbance is read by the UV-Vis spectrophotometer at λmax of the drug and the concentration is reported referring to drug calibration curve.This process has been repeated at 5 different temperatures and then using the cosolvency models the amount of drug solubility has been predicted and finally experimental data and predicted data have been compared and correlated.Results:Based on experimental data, we find the solubility of deferiprone increases with the increase in the mass fraction of PEG400 and temperature. So that the highest solubility of deferiprone is observed for naet PEG400 at 313.2K. Also the lowest solubility of deferiprone was reported for neat 2-propanol at 293.2K. Conclusion:The solubility of deferiprone increased with the increase in temperature and the mass fraction of PEG400. Also, the experimental data were correlated with the data of different cosolvency models and good results were obtained from data modeling.