

It is methadone, but that is just a synthetic opioid. They say it is slower acting, and not as euphoric, but that all changes when you bang it. Some places will watch you take it though. However most don’t bother, they just want the money from the government and give you the pills.
It is very popular in Mexico, central, and south America. It is also very popular in a lot of the US due to its ubiquity in Mexico.