Descriptive terms Parts of solvent needed for 1 part solute Very soluble <1 Freely soluble 1-10 Soluble 10-30 Sparingly soluble 30-100 Slightly soluble 100-1000 Very slightly soluble 1000-10,000 Practically insoluble or insoluble >10,000

Table 2: Classifying solubilities of drugs as per US Pharmacopeia (USP, 2011).