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5098598 
Journal Article 
Film formation by magnesium stearate during mixing and its effect on tableting 
Bolhuis, GK; Lerk, CF; Zijlstra, HT; De Boer, AH 
1975 
1 
Pharmaceutisch Weekblad
ISSN: 0031-6911 
110 
Apr 18 1975 
IPA COPYRIGHT: ASHP It was shown that the degree of mixing of particulate solids with magnesium stearate (I) can greatly reduce the strength of the tablets made. The effect varies with the physical nature of the excipients. The phenomenon is caused by the formation of a lubricant film upon the substrate as a result of the adhesion to the substrate surface of the I molecules which are sheared off from the I crystals during the mixing process. The hydrophobic film markedly affects the dissolution rate of soluble components. Excipients studied included Avicel PH-101 (microcrystalline cellulose) and Avicel PH-102, Elcema G-250 (microfine cellulose), STA-Rx-1500 (starch) Emcompress special (dicalcium phosphate dihydrate), dextrose monohydrate, lactose, amylose V, and coarse crystalline and powdered sodium chloride. The results show for both amylose V and powdered sodium chloride tablets, a dramatic decrease in crushing strength with an increase in mixing time. Amylose V loses its binding properties when compressed from intensively mixed blends containing about 0.04% I.