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Emulsification and Volatilization Technology for Microspheres Preparation

CD Formulation offers three types of emulsification and volatilization technologies for the preparation of drug microspheres, which can be customized according to the needs of your project. The emulsification and volatilization technology mainly includes O/W emulsification technology, O1/O2 emulsification technology, and complex emulsion-liquid drying technology, while the O/W emulsification method is suitable for the preparation of fat-soluble drug microspheres and the latter two methods are commonly used for the preparation of water-soluble drug microspheres.

Emulsification Solvent Volatilization Technology

O/W emulsification technology

Organic solvent dissolved with drug and polylactic acid is added to the aqueous phase containing emulsifier to form O/W emulsion by mechanical stirring or ultrasonic waves, the organic solvent in the inner phase is removed, and polylactic acid and drug are deposited to form microspheres. This method has a low encapsulation rate for water-soluble drugs. This is due to the gradual diffusion of the drug into the aqueous phase during solvent evaporation. Pre-preparation of microspheres with saturated aqueous solution of drug as aqueous phase can effectively prevent the diffusion of drug from organic phase to aqueous phase and significantly improve the drug loading and encapsulation rate of microspheres.

O1/O2 emulsification technology

Microspheres can be prepared by emulsifying the organic phase with dissolved drug and polymer in an immiscible organic phase containing emulsifier.

Complex emulsion-drying-in-liquid technology

This method is improved on the basis of the traditional emulsification solvent volatilization method by adding the aqueous solution or suspension of the drug to the organic solvent with polymer dissolved in it and stirring or ultrasonic shaking to make a primary emulsion (W/O type), then transfer the primary emulsion to the aqueous solution containing stabilizer, homogenize into a compound emulsion (W/O/W type), remove the organic solvent, solid-liquid separation, washing and drying.

According to different applications, different emulsification and volatilization technologies can be selected for product customization of microspheres.

Factors Affecting the Production of Microspheres

  • Polymers

Polymer concentration, relative molecular mass size and composition all affect the properties of microspheres. Polymer concentration affects the deposition rate during sphere-forming. The higher the concentration, the slower the deposition rate, the larger the particle size of the microspheres, the looser the structure, and the faster the drug release.

  • Drug

The drug properties significantly affect the stability of the microsphere polymer crosslinking, and the drug content affects the microsphere size, specific surface area and gap ratio. For the microspheres prepared by O/W process, the drug with large water solubility can easily diffuse into the aqueous phase, and the encapsulation rate and drug loading capacity are lower than those of fat-soluble drugs.

  • Organic solvents

The solubility of organic solvents in the continuous phase is the key to the particle size, encapsulation rate and drug loading capacity of microspheres.

  • Emulsifier

The solvent volatilization method often uses polyethylene (PVA), gelatin, hydroxypropyl methylcellulose (HPMC), and tween as emulsifiers. The type, concentration and emulsification time of the emulsifier are closely related to the size of the emulsion droplets formed, which directly affects the quality of the microspheres.

  • Aqueous phase composition

The addition of buffers, salts or other additives to the aqueous phase can change the solubility of drug and organic solvents in the aqueous phase, thus increasing the drug loading and encapsulation rate, and the sudden release effect is reduced.

  • Solvent evaporation rate

The yield and encapsulation rate of microspheres made by reduced pressure evaporation are higher than those made by atmospheric pressure evaporation.

  • Droplet dispersion methods

The methods of droplet dispersion include mechanical stirring, ultrasound, electric potential dispersion, etc. The stirring speed can affect the particle size and encapsulation rate of microspheres.

If you are interested in our technology, please feel free to contact us and we will develop the best solution for you.

Please note: Our products and services are not intended to be used directly in diagnostic or therapeutic procedures.
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