Yellow Ointment, USP is prepared by combining yellow wax and petrolatum in which ratio?

• A. Yellow Ointment, 50 g wax and 950 g petrolatum
• B. Yellow Ointment, 100 g wax and 900 g petrolatum
• C. Yellow Ointment, 75 g wax and 925 g petrolatum
• D. Yellow Ointment, 25 g wax and 975 g petrolatum

Answer: (A)

Yellow Ointment, USP is a petrolatum base thickened with a small amount of yellow wax to achieve a semi-solid, spreadable texture. The standard preparation uses a ratio of one part wax to nineteen parts petrolatum, which is about five percent wax by weight. This balance provides sufficient firmness to hold form yet still spreads smoothly when applied. Increasing the wax makes the ointment stiffer and harder to spread, while decreasing the wax makes it too greasy and soft. So the ratio that aligns with the USP specification is the one that yields roughly five percent wax, giving the typical yellow ointment consistency.