Which of the following substances is considered a List 1 chemical?

The correct selection is based on the classification of chemicals as regulated under the Controlled Substances Act and the Chemical Diversion and Trafficking Act, which distinguishes between different categories based on their potential for abuse or illegal diversion.

Pseudoephedrine is defined as a List 1 chemical because it is often a precursor in the illegal manufacturing of methamphetamine. This classification leads to stricter regulations surrounding its sale and distribution, recognizing the substance's potential misuse in the production of controlled substances.

The other substances listed—acetaminophen, ibuprofen, and diphenhydramine—are not recognized as List 1 chemicals. These drugs are over-the-counter medications used for pain relief, fever reduction, and allergy treatment, and they do not play a significant role in the illegal drug manufacturing process in the same way that pseudoephedrine does. Understanding this distinction is critical for pharmacy practice and regulatory compliance, as it impacts inventory management and the ability to dispense these medications responsibly.