Which of the following is a controlled substance?

Controlled substances are drugs that are regulated by law due to their potential for abuse or addiction. They are categorized into schedules based on their medical use, potential for abuse, and safety or dependence risk.

Phenergan with Codeine contains codeine, which is an opioid used to treat cough and pain. Because codeine has a considerable potential for abuse and can lead to psychological or physical dependence, it is classified as a controlled substance. This classification ensures that the prescribing and dispensing of medications containing codeine are closely monitored to prevent misuse.

On the other hand, Zoloft is an antidepressant that does not fall under controlled substance regulations, as it does not have a high potential for abuse. Lantus, an insulin product, is also not a controlled substance, as it is used to manage diabetes and is essential for metabolic control. Nexium is a proton pump inhibitor for acid-related disorders and isn’t classified as a controlled substance either.

Thus, Phenergan with Codeine stands out as the only choice that meets the criteria as a controlled substance due to its codeine content.