Which of the following substances is NOT classified as a controlled substance?

Ibuprofen is categorized as an over-the-counter (OTC) medication that is commonly used to relieve pain, reduce inflammation, and lower fever. It is classified as a nonsteroidal anti-inflammatory drug (NSAID) and does not have the potential for abuse or dependence, which is why it is not classified as a controlled substance under the Controlled Substances Act.

Controlled substances, on the other hand, fall into specific schedules based on their medical use, potential for abuse, and safety or dependence issues. Hydrocodone, alprazolam, and phenobarbital are all recognized as controlled substances. Hydrocodone is an opioid analgesic used for pain relief, alprazolam is a benzodiazepine used to manage anxiety and panic disorders, and phenobarbital is a barbiturate used as a sedative and anticonvulsant. Due to their potential for addiction and abuse, these substances are regulated under federal law and require special prescriptions or monitoring.

Understanding the classifications of different substances helps in recognizing the legal requirements associated with dispensing and prescribing medications, which is crucial for pharmacy practice.