In drug manufacture, fine chemicals are pure, single chemical substances that are produced by chemical reactions. Examples of fine chemicals are intermediates for drug production and bulk active pharmaceutical ingredients ready to be compounded with inert pigments, solvents and excipients and made into dosage forms. An Active Pharmaceutical Ingredient, or API, is the substance in drug that is pharmaceutically active. ... In biology, pigment is any material resulting in color in plant or animal cells which is the result of selective absorption. ... A substance is soluble in a fluid if it dissolves in the fluid. ... An excipient is an inactive substance used as a vehicle for medication, or an active ingredient. ...