International Numbering System (INS) for Food Additives: 553b
Food additives Europe numbers: E553b
Functional Category
Anticaking agent; glidant; tablet and capsule diluent; tablet and capsule lubricant
Applications in Pharmaceutical Formulation
Talc was once widely used in oral solid dosage formulations as a lubricant and diluent, see Table I,(1–3) although today it is less commonly used. However, it is widely used as a dissolution retardant in the development of controlled-release products.(4–6) Talc is also used as a lubricant in tablet formulations;(7) in a novel powder coating for extended-release pellets;(8) and as an adsorbant.(9) In topical preparations, talc is used as a dusting powder, although it should not be used to dust surgical gloves; see Section 14. Talc is a natural material; it may therefore frequently contain microorganisms and should be sterilized when used as a dusting powder; see Section 11. Talc is additionally used to clarify liquids and is also used in cosmetics and food products, mainly for its lubricant properties.
Description
Talc is a very fine, white to grayish-white, odorless, impalpable, unctuous, crystalline powder. It adheres readily to the skin and is soft to the touch and free from grittiness.
Stability and Storage Conditions
Talc is a stable material and may be sterilized by heating at 1608C for not less than 1 hour. It may also be sterilized by exposure to ethylene oxide or gamma irradiation.(10) Talc should be stored in a well-closed container in a cool, dry place.
Incompatibilities
Incompatible with quaternary ammonium compounds.
Safety
Talc is used mainly in tablet and capsule formulations. Talc is not absorbed systemically following oral ingestion and is therefore regarded as an essentially nontoxic material. However, intranasal or intravenous abuse of products containing talc can cause granulomas in body tissues, particularly the lungs.(16–18) Contamination of wounds or body cavities with talc may also cause granulomas; therefore, it should not be used to dust surgical gloves. Inhalation of talc causes irritation and may cause severe respiratory distress in infants;(19) see also Section 15. Although talc has been extensively investigated for its carcinogenic potential, and it has been suggested that there is an increased risk of ovarian cancer in women using talc, the evidence is inconclusive.(20,21) However, talc contaminated with asbestos has been proved to be carcinogenic in humans, and asbestos-free grades should therefore be used in pharmaceutical products.(22) Also, long-term toxic effects of talc contaminated with large quantities of hexachlorophene caused serious irreversible neurotoxicity in infants accidentally exposed to the substance.(23)