Spray drying technique in solid dispersion preparation (P4)

Based on the principle of solvent evaporation, the techniques commonly used to prepare solid dispersion systems are spray-drying, fluid-bed granulation, lyophilization and copper. co-precipitation. Spray drying method is the process of converting raw materials from liquid into dry particles by spraying and drying in hot air for a short time. The input materials of the process can be in the form of a solution, suspension or emulsion.

Solvent evaporation method

The solvent evaporation method is one of the most popular methods in the pharmaceutical industry to improve the solubility of poorly water-soluble drugs. This method was developed mainly for heat-labile ingredients because the drug and excipients are mixed using a solvent instead of heat as in the hot melt method. The main advantage of this method is to avoid decomposition of the drug and excipients because the temperature required for evaporation is low.

General principle of solvent evaporation method

– Dissolution: drug substance and excipients are dissolved in a volatile solvent for homogeneous mixing. It is necessary to choose a suitable solvent to dissolve both the drug substance and excipients, and at the same time be safe for use in pharmaceuticals.

– Evaporation: The solvent is removed using different techniques to obtain a solid dispersion.

– Finishing: The solid dispersion is further processed (crushing, sieving, mixing…) to obtain the desired dosage form.

This method has been used to improve the solubility of various pharmaceutical substances, including azithromycin, tectorigenin, flurbiprofen, cilostazol, ticagrelor, piroxicam, indomethacin, loratadine, diclofenac, abietic acid, efavirenz and repaglinide. Solvent evaporation method is also often used to improve the solubility of poorly water-soluble anti-cancer drugs such as paclitaxel and docetaxel.

manufacturing method for amorphous solid dispersion

Based on the principle of solvent evaporation, the techniques commonly used to prepare solid dispersion systems are spray-drying, fluid-bed granulation, lyophilization and co-precipitation.

Spray-drying technique

Principle

Spray drying method is the process of converting raw materials from liquid into dry particles by spraying and drying in hot air for a short time. The input materials of the process can be in the form of a solution, suspension or emulsion. The spray drying process includes 3 main stages:

Stage 1: convert the liquid material to be dried into mist (liquid droplets dispersed in the air) thanks to the mist sprayer in the spray dryer.

Stage 2: disperse the liquid droplets into the drying air stream in the drying chamber. The material is sprayed into mist so the contact area between the liquid drops and the drying air stream is very large. Therefore, the moisture in the material evaporates quickly.

Stage 3: separation of the dried product from the gas stream using a cyclone, filter bag or electrostatic field

Nguyên lý và thông số quan trọng của kỹ thuật sấy phun — Principles and important parameters of spray drying technique

Advantages and disadvantages

Advantages:

- Widely used in the production of products from sterile to non-sterile.
- Large capacity (can range from several kg/hour to several tons/hour).
- Works automatically and continuously.
- Adjust machine parameters to change product properties.
- Spray-dried powder particles are spherical in shape and similar in size.
- Can dry products that are easily damaged by heat [3].

Disadvantages:

Bulky equipment.
Low thermal efficiency (a large amount of hot air passes through the drying chamber butdoes not participate in the drying process of the product)