Final answer:
Methadone 40mg sales are restricted to combat prescription drug abuse and its diversion to the illicit market, especially in the context of the opioid crisis where individuals may turn to substances like heroin and fentanyl.
Step-by-step explanation:
Sales of methadone 40mg from manufacturers are restricted to certain medical entities due to its potential for abuse and its status as a controlled substance. Methadone is a synthetic opioid used for pain relief and as part of drug addiction detoxification and maintenance programs. Given the opioid epidemic and the FDA's 2013 recommendation for tighter controls on prescriptions, medications like methadone are closely regulated to prevent their diversion into the illicit market. The opioid crisis has been exacerbated by individuals turning to illegal substances like heroin and synthetic opioids such as fentanyl when they are unable to obtain prescription opioids like oxycodone. The inclusion of powerful synthetic opioids in the drug supply has led to a dramatic increase in overdose deaths.