ULTRASONIS TESTING OF PRESSED LISINOPRIL TABLETS

Abstract

The article analyses the results of modern ultrasonic research in the fields of biophysics, medicine, pharmacology, and pharmacy from the standpoint of modern fundamental science. The possibilities of using experimental ultrasonic methods to study the mechanical properties of pressed pharmaceuticals are shown. The use of ultrasonic methods is based on the relationship between the structure of the drug and its elastic dynamic characteristics, i.e., elastic modulus and internal friction. The advantage of ultrasonic methods is that they allow to study the force field of a heterogeneous structure, which determines the speed of ultrasound propagation, its absorption, kinetics and dynamics of structural units and to obtain data on the internal structure of the material without its destruction. The objects of the study were dosage forms in the form of pressed tablets of lisinopril-astrafarm (pharmacotherapeutic group of ACE inhibitors) with different content of the active substance. The density of the test samples was determined by hydrostatic weighing with a relative error of 0.3%. The experimental setup for determining the acoustic parameters of pressed pharmaceuticals is based on the pulse mode method. The operation of the experimental setup is based on the passage of longitudinal and transverse ultrasonic waves (ultrasound) through a sample immersed in an immersion liquid. The condition of a good acoustic contact between the liquid and the sample is usually fulfilled automatically. This makes it possible to consider the sample as an equivalent segment of a certain length d, loaded at both its ends with a resistance equal to the wave resistance of the liquid, which is permissible when using high-frequency pulses, since no standing waves occur in the liquid. The medium of propagation of ultrasonic waves in the cuvette is silicone oil of PFMS-4 grade. The results of experimental studies of the real parts of the dynamic modules have shown that their values indicate a different structural organisation of the micro- and macrolevels. The nature of the dependence of the real parts of the dynamic moduli indicates structural changes at the interface of the tablet components. The determined mechanical characteristics of pressed pharmaceuticals allow predicting their behaviour under conditions of storage, transportation, use, and manufacturing processes.