Which of the following is NOT a Schedule 2 substance?

Phenobarbital is classified as a Schedule IV controlled substance under the Controlled Substances Act, whereas the other substances listed—methadone, hydrocodone, and meperidine (Demerol)—are classified as Schedule II substances.

Schedule II substances have a high potential for abuse, which may lead to severe psychological or physical dependence. They are recognized for medical use and have accepted medical indications, but their prescribing and dispensing are subject to strict regulations due to the potential risks associated with their use.

In contrast, phenobarbital, while it can be used as a medication for conditions such as seizures, does not have the same level of abuse potential as the Schedule II drugs listed and hence is not classified under that schedule. Understanding the scheduling system is crucial for pharmacists and healthcare providers to ensure compliance with laws governing the prescription and handling of controlled substances.