Pharmaceutical grade dioctahedral smectite is a type of clay mineral commonly used as an inactive pharmaceutical ingredient and medication excipient. This article discusses what dioctahedral smectite is, its properties and uses in the pharmaceutical and cosmetic industries.
What Is Dioctahedral Smectite?
Smectite refers to a group of minerals that have a layered or sheet-like structure. They are part of the clay mineral family and exhibit swelling properties when exposed to water.
Dioctahedral smectite specifically refers to smectite minerals that have a dioctahedral crystal structure. This means there are only two-thirds of the metal ions needed to fill octahedral sites within their crystal lattice. The missing ions allow them to absorb lots of water between layers.
Two common types of dioctahedral smectite are:
• Montmorillonite – A very soft, highly absorbent clay mineral used in many applications. It can absorb up to twice its weight in water.
• Bentonite – A rock formed from weathered volcanic ash composed mainly of montmorillonite minerals. It easily absorbs water and swell up.
Pharmaceutical grade dioctahedral smectite is specially purified and processed to meet purity specifications for medicinal and cosmetic applications. It goes through filtration, washing and heating steps to remove contaminants and concentrated ions.
Properties And Functions In Pharma And Cosmetics
The main properties that make dioctahedral smectite useful in pharma and cosmetics are:
• High Absorbency – It can absorb many times its own weight in water and organic molecules, acting as a thickening agent. This property helps increase the viscosity of liquids.
• Swelling Properties – The clay’s layered structure can expand significantly when exposed to water, improving water retention of formulations.
• Barrier Effect – The swollen clay particles can form a physical barrier that controls diffusion of ingredients and moisture. This improves the stability of products.
• Binding and Structure – The clay’s plate-like particles can bind with other ingredients, providing structure and body to gels and pastes.
• Opacity – Pharmaceutical grade smectite gives opaque properties to products, which is desirable for some cosmetics.
In the pharmaceutical industry, dioctahedral smectite finds use as an inactive ingredient in tablet and capsule formulations. It acts as a disintegrating agent, glidant, diluent and anti-caking agent.
In cosmetics, smectite clay is mainly used as a thickening agent in products like mud masks, scrubs, and shampoos. It improves the consistency, stability and application properties of formulations. The clay can also act as an absorbent for excess oils and a protective barrier on skin.