Narcan is an antagonist for Fentanyl, a sedation drug used in the lab. Fentanyl is a potent opioid analgesic that is commonly used for pain management and anesthesia. Narcan, also known as naloxone, is a medication used to reverse the effects of opioid overdose, including the respiratory depression caused by opioids like Fentanyl. It works by binding to the same receptors in the brain that opioids bind to, effectively blocking their effects and restoring normal respiration. Therefore, Narcan is specifically used to counteract the sedating effects of Fentanyl in the lab.