______ permit incorporation of aqueous solutions, are insoluble in water, and absorb alcohol and small amounts of water.

• A. Anhydrous bases
• B. White ointment
• C. Yellow Ointment
• D. White Petrolatum

Answer: (A)

The key idea is how ointment bases handle water and water-containing drugs. Anhydrous bases are lipophilic, water-insoluble bases that can take up water to form a water-in-oil emulsion. That means they permit incorporation of aqueous solutions into the base, while still being insoluble in water themselves. They also can absorb small amounts of alcohol, which fits the behavior of these absorption bases.

White ointment and white petrolatum are pure hydrocarbon bases and do not form emulsions with water; they don’t readily incorporate aqueous solutions. Yellow ointment is also petrolatum-based and behaves similarly. So the scenario described best matches anhydrous (absorption) bases, which are designed to absorb water and some alcohol while remaining largely water-insoluble.