Which of the following substances is no longer legally produced?

Quaaludes, also known by their generic name methaqualone, are no longer legally produced due to their designation as a Schedule I controlled substance in the United States. This classification is given to drugs that are considered to have a high potential for abuse and no accepted medical use, contributing to their eventual ban.

Methaqualone was widely prescribed in the 1970s for its sedative and hypnotic effects. However, as awareness of its addictive potential and the issues related to misuse became evident, regulations tightened until its production was halted altogether. This contrasts with the other substances listed: cocaine is an illegal drug with no legitimate medical use but is produced illegally; oxycodone, although regulated, is still legally manufactured for medical use; and Adderall, which contains amphetamine and is prescribed for ADHD, is also legally produced. Thus, the classification and regulatory status of Quaaludes distinctly set it apart from the other listed substances.