For example, when administering the same doses of sulfadimezine, micronized and obtained in factory production without additional grinding, it was found that in the first case in the blood plasma of people the content of the drug substance is 40% higher, the maximum concentration is reached 2 hours earlier, and the total amount of absorbed substance by 20% more than in the second case. When the particle size of acetylsalicylic acid (aspirin) is reduced by 30 times, its analgesic, antipyretic and anti-inflammatory effect is increased by 2 times. Reducing the size of griseofulvin particles from 10 microns to 2.6 microns allows reducing the total dose of the drug by 50% (from 1 to 0.5 g), while maintaining a constant concentration of the drug in the blood. The highest concentration of phenacetin in the blood is observed when using the drug with a particle size of 75 microns, and when using the same substance with a particle size of 250 microns, its content in the blood markedly decreases. Enhancement of therapeutic effect when reducing the particle size of drugs can be observed in any dosage form – suspensions, ointments and others, so when grinding is important to follow the technological rules and techniques to achieve the optimal particle size. However, in some cases, excessive grinding can lead to a decrease in the pharmacotherapeutic activity of drugs. This is largely due to an increase in hydrolytic processes or a decrease in their stability in the presence of digestive juices with an increase in the contact surface of the drug substance with biological fluids. For example, the activity of drugs such as penicillin and erythromycin decreases sharply with increasing dispersibility. In the process of dispersion also occurs a decrease in free surface energy due to adsorption of moisture and gases from the air. In this case, the powder mixture becomes loose, sometimes damp, particles stick together, forming larger aggregates, and substances are adsorbed on the walls of the apparatus.

In addition, increasing the degree of dispersibility increases the likelihood of side effects of drugs. To reduce side effects, substances are prescribed in dosage forms in which they are dispersed in the form of coarse particles or crystals. If the GF does not specify the degree of grinding of specific powders, the finest powders should be prepared. Grinding of the drug is used to achieve homogeneity of mixing, to eliminate large aggregates in clumping and adhesive materials, to increase technological and biological effects. Grinding of powders leads to an increase in the strength and number of contacts between particles and results in the formation of strong conglomerates. Depending on the particle size of the starting material, a distinction is made between crushing (grinding of large pieces of material) and milling (powdering – grinding of small particles). One of the tasks of the crushing process is to achieve an optimal particle size, taking into account: properties of the initial substances and their structure; application of crushing rules and technological methods; crushing time (set experimentally). Crushing produces particles of different sizes and shapes. In the process of splitting more homogeneous in size and shape particles are formed, although the shape, as in crushing, is not constant. The size and shape of particles in breaking are about the same as in splitting. Cutting and sawing result in the division of the body into particles of predetermined size and shape. Grinding produces a fine powdery product. Depending on the physical and mechanical properties of the starting materials, the following grinding methods are used: hard and brittle material – crushing, impact; hard and ductile material – crushing, sawing; brittle, medium hardness – impact, splitting and abrasion; ductile, medium hardness – abrasion or abrasion and impact, sawing.