Studies on Interionic interactions of anti-tuberculosis drugs Isoniazid with mixed solvents at different temperatures: Ultrasonic Studies: Studies on Interionic interactions of anti-tuberculosis drugs Isoniazid with mixed solvents at different temperatures: Ultrasonic Studies

Abstract

Density, ρ, and ultrasonic velocity, u of an anti-tuberculosis drug, isoniazid in the aqueous solutions of K₃Cit and Na₃Cit were determined at T= (298.15 to 318.15) K and, p =0.1MPa atmospheric pressure. The experimentally obtained values of ultrasonic velocity, u, and density, ρ have been used to calculate the thermoacoustic properties like isentropic compressibility (β_s), Isothermal Compressibility (β_T), Heat capacity ratio (g), hydration number, n_H, Molar compressibility (W), Acoustic independence (Z), molar sound velocity(R), relative association (R_A), intermolecular free length (L_f), relaxation time(τ), Coefficient of thermal expansion(α) and non-linearity parameters. The results obtained by these processes have been used to analyze the presence of intermolecular interactions existing in the solutions. The effect of concentration and temperature of the solutions on intermolecular interactions were studied at the same pressure.

According to pharmacology, a drug is a chemical structure, when administered to a living organism, produces a biological effect [1]. Pharmacodynamics and physicochemical properties of drugs help to understand drug action, mechanism, and their interaction with an aqueous solution of potassium and sodium citrate at the molecular level [2-3]. Whether a drug is effective or not is mainly depends on its bioavailability which directly affects the solubility of drugs [4]. Hence a desired concentration of drugs is very important for pharmacological action and mechanism due to their less solubility in aqueous solutions. Hence to increase the solubility of drugs some carrier molecules are added [5]. The physicochemical properties of drugs help to understand the solution behaviour of drugs and their applications in the medicinal and pharmaceutical industries. [6-8]. Thus it is very interesting to study thermo acoustical properties of an anti-tuberculosis drug, isoniazid in aqueous solutions of potassium and sodium citrate at different temperatures. The experimentally found density and ultrasonic velocity data were used to calculate the thermo acoustical properties and are used to interpret the presence of various types of intermolecular interactions existing in the studied solutions. The density and ultrasonic velocity values of solutions of isoniazid in pure water at T=(298.15 – 318.15)K are given in Fig1.

   

(a)

(b)

Figure 1: (a) The plot of density, ρ, versus molality, m_A of  in pure water at different temperatures: ▬■▬298.15 K, ▬●▬ 303.15K, ▬▲▬308.15 K ▬▼▬313.15Kand  ▬♦▬318.15K respectively (b) The plot of ultrasonic velocity versus molality, m_A of  in pure water at different temperatures, ▬■▬298.15 K, ▬●▬ 303.15K, ▬▲▬308.15 K ▬▼▬313.15K and  ▬♦▬318.15K respectively

The increase in ultrasonic velocity with an increase of temperature and concentration of isoniazid in water indicated the existence of intermolecular interactions which is increases with temperatures [9-11].