GMP: Causes for Weight Variations during Tableting
Weight variations of the tablets produced is a relatively common problem of the tableting process. But each tableting process aims at producing tablets with a constant weight. The actual cause for this problem is the lack of weighing systems that are sufficiently fast to weigh or dose the required weight for each single tablet. Since this is not possible, each tablet press doses a certain amount of powder into the die and this powder is then pressed into tablets by the upper and lower punch. This means that a volume is dosed, but the quality requirement is the weight. Hence, weight variations in a limited extent are quite normal due to variations in the density of the powder material and to a partially incomplete filling of the dies.
The source of the news: http://www.gmp-compliance.org/enews_04693_Causes-for-Weight-Variations-during-Tableting.html