Which of the following is a fully synthetic opiate?

• A. Morphine
• B. Heroin
• C. Methadone
• D. Codeine

Answer: (C)

The idea being tested is the origin of opiates: natural alkaloids, semi-synthetic derivatives, and fully synthetic opioids. Morphine and codeine are natural opiates, alkaloids directly derived from the opium poppy. Heroin is made by chemically modifying morphine, so it’s considered semi-synthetic. Methadone, however, was completely designed and synthesized in the laboratory and does not come from opium alkaloids; it’s a synthetic opioid. Its structure and origin are non-opioid-alkaloid, yet it acts on mu receptors like other opioids. Because it is not derived from opium, methadone is the fully synthetic opiate.