Effect of vibration time, frequency and acceleration on drug content uniformity.

The effect of different vibration conditions on the segregation tendency of three ordered powder mixes was studied. Segregation of the powders was measured using a cylinder, composed of interlocking units for sampling purposes, mounted on a vibration rig. Ordered mixes containing either Emdex or recrystallized lactose carrier particles mixed with 0.5% fine-particle potassium chloride were stable, except for slight segregation that occurred under severe vibration conditions at frequencies below 50 Hz and accelerations above 22 m s-2. Powder mixes of Dipac with potassium chloride were unstable at most vibration conditions from 20 to 1000 Hz and 7.4 to 29.4 m s-2. The intensity of segregation in vibrated mixes of Dipac with potassium chloride was most marked at frequencies below 50 Hz and accelerations above 22 m s-2. These vibration conditions were found to occur in several commonly-used types of tableting presses. When vibration was prolonged, for periods of 30 to 60 min, there was increased segregation found in ordered mixes.