Solid glidants

Excipients are sub-divided into various functional classifications, depending on the role that they are intended to play in the resultant formulation, for example, fillers, disintegrants, binders, lubricants and glidants. An added complexity is the fact that certain excipients can have different functional roles in different formulation types. Thus, lactose is widely used as a filler or diluent in solid oral dosage forms, for example, tablets and capsules [2] and as a carrier for inhalation products [3]. 

Excipients play a key role in oxidation, either as a primary source of oxidants, trace amounts of metals, or other contaminants. Auto-oxidation of diethylstilbes-terol to the peroxide and conjugated quinone degradation products was attributable to the presence of colloidal silicon dioxide, used as a glidant in solid oral dosage forms [48]. This was ascribed to the fact that silicon dioxide can act as a Lewis acid (an election acceptor or oxidising agent), under anhydrous conditions. 

There are three types of lubricants employed in solid dosage form manufacture. The first class of lubricant is the glidant. The flow properties of a powder can be enhanced by the inclusion of a glidant. These are added to overcome powder cohesiveness. The two other classes of lubricant are antiadherent excipients, which reduce the friction between the tablet punch faces and tablet punches, and die wall lubricant excipients, which reduce the friction between the tablet surface and the die wall during and after compaction to enable easy ejection of the tablet. The level of a lubricant required in a tablet is formulation dependent and can be optimized using an instrumented tableting machine. 

Jones TM. The effect of glidant addition on the flowability of bulk particulate solids. / Soc Cosmet Chem 1970 21 483—500. 

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