A glidant is a substance that is added to a powder to improve its flowability. A glidant will only work at a certain range of

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', '' molar concentration'', '' number concentration'', ...

s. Above a certain concentration, the glidant will in fact function to inhibit flowability. In tablet manufacture, glidants are usually added just prior to compression.

Examples

Examples of glidants include ascorbyl palmitate, calcium palmitate,

magnesium stearate Magnesium stearate is the chemical compound with the formula . It is a soap, consisting of salt containing two equivalents of stearate (the anion of stearic acid) and one magnesium cation (Mg2+). Magnesium stearate is a white, water-insoluble pow ...

fumed silica Fumed silica (CAS_Registry_Number, CAS number 7631-86-9, also 112945-52-5), also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three-dimensional ...

(colloidal silicon dioxide),

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diet ...

and

talc Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula . Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant ...

Mechanism of action

A glidant's effect is due to the counter-action of factors that cause poor flowability of powders. For instance, correcting surface irregularity, reducing interparticular friction and decreasing

surface charge A surface charge is an electric charge present on a two-dimensional surface. These electric charges are constrained on this 2-D surface, and surface charge density, measured in coulombs per square meter (C•m−2), is used to describe the charge ...

. The result is a decrease in the

angle of repose The angle of repose, or critical angle of repose, of a granular material is the steepest angle of descent or Strike and dip, dip relative to the horizontal plane on which the material can be piled without slumping. At this angle, the material ...

which is an indication of an enhanced powder's flowability.

References

Chemical engineering Drug manufacturing Granularity of materials Powders {{material-stub