Wax, Microcrystalline

Synonyms: Amorphous wax; E907; petroleum ceresin; petroleum wax (microcrystalline).

Description: Microcrystalline wax occurs as odorless and tasteless waxy lumps or flakes containing small irregularly shaped crystals. It may vary in color from white to yellow, amber, brown, or black depending on the grade of material; pharmaceutical grades are usually white or yellow.

Chemical Name: Microcrystalline wax

Coating agent; controlled-release agent; stiffening agent.

• Microcrystalline wax is used mainly as a stiffening agent in topical creams and ointments.

• The wax is used to modify the crystal structure of other waxes (particularly paraffin wax) present in a mixture so that changes in crystal structure, usually exhibited over a period of time, do not occur.

• Microcrystalline wax also minimizes the sweating or bleeding of oils from blends of oils and waxes.

• Microcrystalline wax generally has a higher melting point than paraffin wax, and higher viscosity when molten, thereby increasing the consistency of creams and ointments when incorporated into such formulations.

• Microcrystalline wax is also used in oral controlled-release matrix pellet formulations for various active compounds and as a tablet- and capsule-coating agent.

• In controlled-release systems, microcrystalline wax coatings can also be used to affect the release of drug from ion-exchange resin beads.

• Microcrystalline wax is also used in confectionery, cosmetics, and food products.

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Microcrystalline wax is mainly used in topical pharmaceutical formulations but is also used in some oral products. It is generally regarded as a nontoxic and nonirritating material.

Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection is recommended.

Paraffin; wax, white; wax, yellow.