Question

While preparing the following:
Rx
 Salicylic acid: 3 g
   Sulfur ppt: 7 g
   Lanolin: 10 g
   White petroleum: 10 g
The pharmacist should:

• A. Use a rubber spatula to weigh and levigate the salicylic acid
• B. Mix the powders using geometric dilution in a mortar
• C. Place on an ointment tile and levigate the ingredients using geometric dilution
• D. All the above

Answer 1

The Correct Option is C

The question pertains to the compounding process in pharmacy, specifically for preparing an ointment containing salicylic acid, sulfur, lanolin, and white petroleum. The correct answer is to place on an ointment tile and levigate the ingredients using geometric dilution. Let's break down the reasoning and process involved in this choice:

1. **Understanding Levigation and Geometric Dilution**:
   • Levigation involves reducing the particle size of a solid ingredient by mixing it with a small amount of liquid or with another ingredient that allows easier blending. This is necessary for obtaining a smooth paste, especially for substances like salicylic acid in ointments.
   • Geometric Dilution is a technique used when mixing two powders of unequal quantities. It involves adding equal amounts of each ingredient step-by-step to ensure an even distribution throughout the mix.
2. **Rationale for the Correct Option**:
   • Using an Ointment Tile: An ointment tile provides a smooth, flat surface ideal for this type of preparation. It allows the pharmacist to adequately blend and levigate the ingredients.
   • Levigating Ingredients Using Geometric Dilution: Applying geometric dilution on the ointment tile ensures that the ingredients are uniformly mixed, avoiding concentration differences and ensuring therapeutic efficacy.
3. **Why Other Options Are Incorrect**:
   • Using a rubber spatula to weigh and levigate the salicylic acid is not as precise or effective as using an ointment tile for the full levigation process.
   • Mixing the powders using geometric dilution in a mortar is less effective because ointment tiles provide better control for levigation.
   • The option 'All the above' is incorrect as it includes processes that do not fully apply or are less effective.

In conclusion, the use of an ointment tile combined with levigation through geometric dilution offers the best method for preparing an effective and homogeneous ointment combination.