Morphine, Vicodin, and Oxycodeine: Why are opioids used when they are so addictive?

You may be familiar with several of the popular opioid medications (morphine, vicodin, and oxycodone) prescribed to people with severe pain. Also, you may have heard about the serious addictive effects which may result from taking these drugs. However, two questions that seem to never be asked are: 1) why are these drugs so addictive? and 2)if they are so addictive why to doctors continue prescribing these opioid medications?.  As part of this week’s discussion, we attempted to analyze the addictive nature of opioid drugs and understand why we continue to use such drugs even though they are highly addictive.
The article we looked at focused on a molecule called glutamate, which is found in most part brain, and its involvement in the opioid addiction mystery. It turns out glutamate may play a bigger role in addiction than previously thought. Since glutamate is one of the most abundant neurotransmitters in the brain, it is found in many different areas including the ventral tegmental area and nucleus accumbens which are believed to play a prominent role in addiction. When opioids are used, more glutamate neurotransmitters are released and interact through many complex pathways causing an increase in dopamine, which is the neurotransmitter associated with the reward. This causes the body to think it is being rewarded for taking opioids. Additionally, when glutamate binds with its own receptors it can cause addiction and withdrawal-like feelings by acting through many different biological pathways. However, I would like to note addiction is much more complicated than this and more research is needed to understand addiction better.¹
This leads us to the question why do we use opioid medications if they are so addictive? As discussed in class the key reason seems to be the effectiveness of stopping pain. Besides opioid drugs, the other common type of pain killers are non-steroidal anti-inflammatory drugs (NSAIDS) which includes Advil and Aleve; acetaminophens likes Tylenol; and aspirin. All three pain killers act by stopping an enzyme (called cyclooxygenase or COX) found throughout the body which is responsible for feeling inflammation and pain. NSAIDS and aspirin block this enzyme in the areas outside the brain while acetaminophens block the enzyme in the brain. Although these drugs are successful, they come with side-effects such as liver and kidney damage and blood thinning after extended periods of time. ² However, opioid medications act in a different way therefore making them excellent pain relievers. Opioids change the perception of pain by working on the spinal cord and the brain. Opioids pain killing characteristic works by closing and opening a variety of channels in the brain resulting in a reduction of the brains ability to feel pain. Closing and opening these particular channels are more effective at reducing pain than by stopping the COX enzyme either in the brain or the peripheries. Additionally, as a result of changing channels instead of stopping an enzyme, opioid usage do not have many of the long-term side-effects associated with the other pain killers. However, since they interact with channels in the brain addiction is much more prevalent than with the other drugs.³
Therefore to summarize, opioid medications such as morphine, vicodin, and oxycodone acts in such a way that when taken glutamate is released and through several pathways causes dopamine to be released. This results in a feeling of reward. Additionally, when excess glutamate binds to certain receptors in the brain one feels addictive and withdrawal-like feelings. However, the reason why opioids medications continue to be used is because they are more affective at reducing pain and contain fewer physical side-effects as compared to NSAIDS, acetaminophens, and aspirin.
Finally, this raises questions about what should be done with opioid medications. Would you rather live a life without pain but have the possibility of becoming addicted to your medication or would you rather live with pain but know you will not be overcome by the psychology effects of addiction?  Or should scientists continue expensive research in the hopes of stopping the addictive nature of the opioid. There seems to be not right answer but it does appear opioid medications are going to remain in our society for the foreseeable future.
Sources:
1) http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0000802/
2)http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004928/
3)http://www.webmd.com/pain-management/opioid-analgesics-for-chronic-pain