Final answer:
Suppository bases made of fats and glycols, such as glycerophospholipids and propylene glycol, dissolve at body temperature to deliver medication.
Step-by-step explanation:
Suppository bases are typically made of substances like fats and glycols that can be dissolved or melted at body temperature. These bases act as carriers for medication. Glycerophospholipids, for instance, are made up of glycerol, two fatty acids, phosphoric acid and a base such as choline, as seen in Phophatidyl choline or lecithin. Glycerol is also used in pharmaceutical formulations as a solvent, such as in the production of suppositories. Other fats, such as lard, tallow, and butter, also contain glycerine, which can form natural esters with carboxylic acids and are also instrumental in the structure of suppositories. Another common base is propylene glycol, used as an ingredient in various edible items and pharmaceuticals, and serves as a solvent in suppositories.