Glidants magnesium stearate

Glidants (e.g., colloidal silicon dioxide, talc) may need to be added to achieve desired flow properties, especially when the drug/filler ratio is relatively high. Usually, there is an optimum concentration of glidant for best flow, often less than 1% for the colloidal silicas (14,15). The following order of effectiveness of glidants has been reported for two powder systems fine silica > magnesium stearate > purified talc (16). 

Glidants Fine silica, talc, magnesium stearate... 

Glidants and lubricants boric acid, colloidal silica, hydrogenated vegetable oils, magnesium stearate-polyethylene glycols, stearic acid, talc. 

Glidants To improve the flow of granules from the hopper to the die cavity to ensure uniform fill for each tablet Fine silica, magnesium stearate, purified talc... 

It must be stressed that the functions of a glidant and lubricant in a tablet formulation are totally different. A few materials, e.g. talc, can act as both glidant and lubricant, but usually two different excipients are needed. Thus, although colloidal silicon dioxide is an excellent glidant, it has no lubricant activity. Conversely, magnesium stearate, despite its popularity as a lubricant, can hinder rather than promote flow. 

Dextrates is a directly compressible tablet diluent used in chewable, nonchewable, soluble, dispersible, and effervescent tablets.It is a free-flowing material and glidants are thus unnecessary. Lubrication with magnesium stearate (0.5-1.0% w/w) is recommended. Dextrates may also be used as a binding agent by the addition of water, no further binder being required. ... 

Lubricants or glidants are also added in small amounts to improve flow properties. Glidants such as fumed silica are often added to lower powder strength. Also note that in contrast, lubricants such as magnesium stearate may actually increase powder strength and adversely lower the flow rate. The primary purpose of... 

Other compounds that may be present in a reservoir system are a dispersion medium of solvent, glidants or anti-adhesive agents (titanium oxide, talc, magnesium stearate, etc.), and agents that further influence the release (various water soluble, but also fat-soluble compounds. 

Excipients used for lubrieation in tablet formulations can have an adverse effect on the dissolution eharacteristics of the final tablet. Hydrochlorothiazide tablets lubrieated with talc have been shown to have improved dissolution properties as eompared to similar tablets lubricated with magnesium stearate (Dawoodbhai et al, 1987). This same study also foimd talc to improve hardness, friability and appearance for some systems when compared to other lubrieants. It was additionally noted that different sources of talc showed signifieant variation in their glidant and lubricant efficiencies. 

---