Introduction to Opioids

An Introduction to Opioids
Illicitly used opioids are the third most common form of illicit drug use worldwide and in most high income countries less than 1% of population has used illicit opioids in the last year. Opioids can be associated with overdose, deaths and other health harms but contributes to less of the global burden of disease than licit substances like alcohol and tobacco.

In a local context more people die of prescription drug overdose in Victoria than all the illegal drugs combined. Prescribed opioids were the third largest cause for overdose deaths (usually in combination with other medications).

Opioids include naturally occurring opiate compounds such as morphine an alkaloid of opium obtained from the poppy plant Papaver somniferum as well as synthetic chemicals. Other examples of opioids include: morphine, methadone, buprenorphine, oxycodone, pethidine, codeine, diacetylmorphine (heroin), fentanyl, pentazocine, hydromorphone, dextropropoxyphene

Opioids act on opioid receptors in CNS to produce analgesia and varying amounts of euphoria and sedation. There are three main types of opioid receptors and they produce the following effects:

  • mu receptors: euphoria, sedation, analgesia, miosis, reduced GI motility, respiratory depression and physical dependence
  • kappa: (spinal cord, basal ganglia and temporal lobes) drowsiness and dysphoria
  • delta: analgesia and cardiovascular effects (hypotension and bradycardia)
The simulation of mu (and delta) receptors are involved in reward systems.
Author: Dr Thileepan Naren
Thileepan is an Addiction Medicine Advanced Trainee and experienced general practitioner with a demonstrated history of working with disadvantaged and marginalized groups.