Opioids. The term opiate is often used as a synonym for opioid, it is more properly limited to the natural opium alkaloids and the semi-synthetics derived from them.

Natural opiates

Alkaloids contained in the resin of the opium poppy including morphine, codeine and thebaine, but not papaverine and noscapine which have a different mechanism of action.

Semi-synthetic opiates

Created from the natural opioids, such as hydromorphone, hydrocodone, oxycodone, oxymorphone, desomorphine, diacetylmorphine (Heroin), nicomorphine, dipropanoylmorphine, benzylmorphine and ethylmorphine.

Fully synthetic opioids

fentanyl, pethidine, methadone, tramadol and propoxyphene.

Endogenous opioid peptides

Produced naturally in the body, such as endorphins, enkephalins, dynorphins, and endomorphins.