The use of specific gravity and density from a pharmaceutical point of view is described in this chapter. You will learn how to measure, calculate, and apply the specific gravity to conveniently determine relative quantities of ingredients that are part of a liquid or a semisolid pharmaceutical dosage form. The importance of units as part of measurement was discussed in Chap. 1. In this chapter, I demonstrate the importance of units from a different perspective by showing how relative numbers of a pharmaceutical parameter change when the corresponding units are changed. I also describe density as a material property that defines the mass of a material in its own volume. Through this definition, you are better equipped to understand the concept of drug concentration discussed in Chap. 4.
Specific gravity Density Gravimetric units Apothecary units
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Density and specific gravity. Description: (a) Differences between density and specific gravity. (b) Converting density from gravimetric to apothecary units. (c) Determining the specific gravity of liquid dosage products from the density of pure ingredients (MP4 724012 kb)