The term “Disperse system” refers to a system in which one substance (dispersed phase) is distributed, in discrete units, throughout a second substance/phase called (continuous phase). or
Dispersed systems consist of at least two phases, the substance that is dispersed known as the dispersed (or) internal phase, and a continuous (or) external phase.
Dispersion system include following preparation used in pharmaceutical products.
Classification of Dispersion system
Based on the particle size of the dispersed phase, dispersions are generally classified as molecular dispersions, colloidal dispersions, and coarse dispersions.
Molecular dispersions
Colloidal dispersions
Coarse dispersions
Molecular dispersions have dispersed particles lower than 1.0 nm in size. Colloidal dispersions have particle sizes between 1 nm and 1mm. Microemulsions, nanoparticles, microspheres are some of the examples of colloidal dispersions. Coarse dispersions have a particle size greater than 1nm, which includes suspensions and emulsions.
In pharmacy, dispersions are found in a wide variety of dosage forms and in nearly all routes of drug administration. Examples range from solutions of very large molecules (macromolecules) such as albumin and polysaccharides to liquid suspensions of “nano”-sized crystals (nanocrystals) and of “micro”-sized droplets (microemulsions), to coarse (larger particle) emulsions and suspensions.
Coarse Dispersion
Coarse dispersions have a particle size greater than 1nm, which includes suspensions and emulsions.