Which entity enforces regulations regarding the distribution of prescription drugs?

The Drug Enforcement Administration (DEA) is the entity responsible for enforcing regulations concerning the distribution of prescription drugs, particularly those substances that are classified as controlled substances. The DEA has the authority to regulate the manufacturing, distribution, and dispensing of these drugs to prevent misuse and illegal trafficking. This includes overseeing prescriptions written by practitioners, ensuring compliance with laws related to controlled substances, and conducting investigations into violations of drug laws.

While the FDA, CDC, and NIH have important roles in public health and regulation, their functions differ significantly from those of the DEA. The FDA deals primarily with the approval and regulation of all drugs released to the market, including ensuring safety and efficacy, but does not itself enforce laws on prescription distribution. The CDC focuses on public health and disease prevention, and the NIH primarily supports medical research. Therefore, the DEA stands out as the key agency focused specifically on controlled substances and their legal distribution, making it the correct choice in the context of this question.