Heat-labile components should be added last when using the fusion method.

• A. True
• B. False
• C. Not applicable
• D. Sometimes

Answer: (A)

When using the fusion method, you melt the base to create a uniform liquid so all ingredients can mix evenly. Heat-labile components are sensitive to high temperatures, so they should not be exposed to the molten mixture for long. Adding them after you remove the heat (or after the base has cooled to a safe temperature) protects them from degradation, volatilization, or loss of potency and helps ensure they’re distributed properly in the final product. If they were added while the base was still molten, their stability could be compromised and the final formulation might have clumping or uneven dosing. So the statement is true: heat-labile components should be added last when using the fusion method.