Packing-Property of Pharmaceutical Powders. VI. Relationship between Compacting Progress and Measurements Variation of Apparent Density in course of Packing of Pharmaceutical Powders

Abstract

Relationship between compacting progress of pharmaceutical powder and measurement variation of apparent density in the case of compacting phenomenon by means of tapping and compacting phenomenon in course of mixing with 1% calcium stearate was examined. At the beginning of compacting of a powder, measurement variation of apparent density decreased with progress of compacting, and their relationship was shown by experimental equation (1). σ_N/ρ_N×100=κ₁ log △ε_N+κ₂(1) where N is progress of compacting, i.e., number of tapping or cumulative revolution of the mixer, ρ_N is the mean value of measured apparent density, σ_N is standard deviation, △ε_N is differential change of porosity between compacting progress N and N+1, and κ₁ and κ₂ are experimental constants. After a certain degree of compacting progress, σ_N/ρ_N×100 did not decrease with decrease of log △ε_N, but became constant. This was considered to be an unavoidal experimental error. σ_N/ρ_N×100=κ₃ (2) Experimental constant κ₃ was thought to change according to the apparatus for measurement, powder, and other conditions. Equation (2) did not apply when abnormal phenomenon, such as segregation of particles in tapping, was likely to occur.