Pain
Opioids
The term opioid refers to different groups of drugs:
- Drugs (alkaloids) derived from the opium poppy (called opiates).
- Examples are morphine and codeine.
- Semi-synthetic opiate drugs, created from the natural opioids.
- Examples are hydromorphone, oxycodone, hydrocodone
- Synthetic "opiate like" drugs.
- Examples are fentanyl and methadone.
There are also endogenous opioid peptides produced naturally in the body such as endorphins.
Putative sites of action are nocicetive nerve endings, spinal cord, thalamus, midbrain and medulla.
Opioids attach to receptors (found mainly in the CNS and GI tract) at the supraspinal and spinal level and outside the central nervous system; they modify the transmission of painful signals and decrease the pain perception.
There are five opioid receptors:
- mu
- kappa
- sigma
- delta
- epsilon
Opium poppy (Papaver somniferum)
