Additional formulation components

Other materials may be needed or desired in a Direct Compression formulation. These include:

• Glidants (to improve flow of the compression mix): use Aerosil 200 at approximately 0.1% to 0.3% w/w if necessary. For low dose drugs a glidant should not be necessary. Aerosil 200 has also been reported to help overcome the potentially deleterious effects of magnesium stearate. Talc (typically used at about 2% to 5%) also has glidant properties.*

• Pigments: typically use aluminium lakes or metal oxides and incorporate them in the first blending stages.

• Stabilisers: For example pH modifiers and antioxidants. To achieve good contact between stabilisers and the API, they should be incorporated at the first blending stage.

• Wetting agents: Typically sodium lauryl sulphate (SLS) (or sometimes di-octyl sodium sulphosuccinate (DOSS)) is used to improve the wettability of hydrophobic drugs. Again the wetting agent should be added, typically at about 1% w/w, in the first blending stage.

* Interaction of lubricants and colloidal silica during mixing with excipients. I. Its effect on tableting. Lerk CF, Bolhuis GK, Smedema SS. Pharm Acta Helv. 1977; 52 (3): 33-39. Interaction of lubricants and colloidal silica during mixing with excipients. II. Its effect on wettability and dissolution velocity. Lerk CF, Bolhuis GK. Pharm Acta Helv. 1977; 52 (3): 39-44.