Classification of Solutions by Solvent Type

Aqueous solutions are the most prevalent of the oral solutions. Drugs are dissolved in water along with any necessary flavorings, preservatives, or buffering salts. Distilled or purified water should always be used when preparing pharmaceutical solutions.

The following are examples of aqueous pharmaceutical solutions.

• Syrups are concentrated, viscous, sweetened, aqueous solutions that contain less than 10% alcohol , e.g. Syrup USP, Wild Cherry Syrup USP.
• Aromatic waters are saturated solutions of volatile oils in water and are used to provide a pleasant flavor or aroma, e.g. Peppermint Water, USP.
• Mucilages are thick, viscous macromolecular solutions produced by dispersing vegetable gums in water. They are commonly used as suspending or thickening agents, e.g. Acacia Mucilage; Tragacanth Mucilage.
• Aqueous acids are dilute aqueous solutions of acids (usually < 10%), e.g. Diluted HCl, USP.