What does the term "Impalpable" describe in relation to pharmaceuticals?

The term "impalpable" in relation to pharmaceuticals describes a substance that is not perceptible to touch. This means that the substance is too fine or small in particle size to be felt through physical contact. In pharmaceutical contexts, this characteristic can be significant when discussing powder formulations or active ingredients, where the fine particles may not be easily tactile or observable. For example, impalpable powders are often used in formulations to ensure uniform distribution in drug products.

The other options do not accurately represent the meaning of "impalpable." A substance that is easily dissolved relates to solubility, not touch sensitivity. Describing a substance that is perceivable to touch contradicts the definition of impalpable. Lastly, a highly reactive chemical does not pertain to the tactile properties of a substance but rather to its reactivity and behavior in chemical processes.