When blending two or more powders the method of geometric dilution is preferred, especially
for unequal quantities of powders. This method ensures that small quantities of ingredients, usually
potent drugs, are uniformly distributed throughout a powder mixture. The steps involved in geometric dilution are the following:
- Weigh ingredients.
- Place the ingredient with the smallest quantity in a mortar.
- Combine this powder with an amount of the material present in the second-largest quantity approximately equal to the amount already in the mortar.
- Triturate the powders until a uniform mixture is formed.
- Add another amount of the second ingredient equal in size to the powder volume already in the mortar and triturate well.
- Continue adding powder to the mortar in this fashion until all the powder ingredients
have been added.
Read more on Mixing of Pharmaceutical Powders in Small-Scale Operations