Interaction of lubricants and colloidal silica during mixing with excipients. I. its effect on tabletting
Lerk, C.F.; Bolhuis, G.K.; Smedema, S.S.
Pharmaceutica Acta Helvetiae 52(3): 33-39
1977
ISSN/ISBN: 0031-6865 PMID: 918125 Document Number: 4265
This paper reports the effect of degree of mixing of different lubricants and of Aerosil 200 on the binding properties of excipients for direct compression, like STARx 1500. In particular the interaction of Aerosil and magnesium stearate during the mixing process has been studied. The results presented indicate that the addition of Aerosil 200 to magnesium stearate in a ratio of about 4 to 1 can suppress the deteriorating effect of magnesium stearate on the crushing strength of tablets made. In general practice, however, a minimum concentration of 0.5 % magnesium stearate is needed to reduce die wall friction whereas a maximum concentration of 0.2 % Aerosil is used as a glidant. In this ratio the deleterious effect of magnesium stearate on the binding properties of different excipients can be reduced, while still retaining the lubricating properties of magnesium stearate, by previous intimate mixing with Aerosil 200 and subsequent blending for a short period with the magnesium stearate.
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