Sferična kristalizacija zdravilnih učinkovin

Spherical crystallization of drugs is the process of obtaining larger particles by agglomeration during crystallization. The most common techniques used to obtain such particles are spherical agglomeration and quasi-emulsion solvent diffusion. Ammonia diffusion systems and crystallo-co-agglomeration are extensions of these techniques. By controlling process parameters during crystallization, such as temperature, stirring rate, type and amount of solvents, or excipient selection, it is possible to control the formation of agglomerates and obtain spherical particles of the desired size, porosity, or hardness. Researchers have reported that the particles produced have improved micromeritic, physical, and mechanical properties, which make them suitable for direct compression. In some cases, when additional excipients are incorporated during spherical crystallization, biopharmaceutical parameters including the bioavailability of drugs can also be tailored.Sferična kristalizacija je postopek izdelave večjih delcev z aglomeracijo manjših med samo kristalizacijo. Najpogosteje uporabljeni tehniki za izdelavo takšnih delcev sta sferična aglomeracija in kvaziemulzija z difuzijo topila. Sistem z difuzijo amoniaka in kristalo-ko-aglomeracija sta razširitvi teh dveh metod. Z nadzorovanjem procesnih parametrov med kristalizacijo, kot sta temperatura in hitrost mešanja, z izbiro lastnosti in množine topil ter z izbiro pomožnih snovi, lahko vplivamo na nastanek aglomeratov in izdelamo sferične delce želenih velikosti, primerne poroznosti ali trdote. Raziskovalci poročajo, da imajo izdelani delci izboljšane pretočne lastnosti, izboljšane druge fizikalne in mehanske lastnosti zaradi česar so primerni za direktno tabletiranje. V nekaterih primerih lahko ob vgradnji ustreznih pomožnih snovi, ki jih dodamo med procesom sferične kristalizacije, izboljšamo tudi biofarmacevtske lastnosti zdravilnih učinkovin vključno s povečanjem biološke uporabnosti

Simulating micrometre-scale crystal growth from solution

Understanding crystal growth is essential for controlling the crystallization used in industrial separation and purification processes. Because solids interact through their surfaces, crystal shape can influence both chemical and physical properties1. The thermodynamic morphology can readily be predicted2, but most particle shapes are actually controlled by the kinetics of the atomic growth processes through which assembly occurs3. Here we study the urea-solvent interface at the nanometre scale and report kinetic Monte Carlo simulations of the micrometre-scale threedimensional growth of urea crystals. These simulations accurately reproduce experimentally observed crystal growth. Unlike previous models of crystal growth4-6, no assumption is made that the morphology can be constructed from the results for independently growing surfaces or from an a priori specification of surface defect concentration. This approach offers insights into the role of the solvent, the degree of supersaturation, and the contribution that extended defects (such as screw dislocations) make to crystal growth. It also connects observations made at the nanometre scale, through in situ atomic force microscopy, with those made at the macroscopic level. If extended to include additives, the technique could lead to the computer aided design of crystals