How Opioids and Alcohol Affect the Brain
Brain regions associated with dependence1
Opioid and alcohol dependence are chronic, relapsing brain diseases that affect both the brain’s cortex and limbic system. Addiction can be devastating both psychologically and physically. While counseling can help patients work through the psychological aspects of dependence, medication may help address the physical changes in the brain.1
The Brain and Pleasure
The limbic system of the brain rewards us for doing life-sustaining activities by releasing endogenous opioids, for example beta endorphins, that attach to opioid receptors in the brain and stimulate the dopamine reward system.2,3 Questions remain about the endogenous opioid system as to the relationship between various opioid peptides and opioid receptors. Endogenous opioids can bind with mu (µ), delta (δ), and kappa (ϰ) opioid receptors.4
The brain and alcohol use
Drinking alcohol can cause an increased release of endogenous endorphins, which can bind to opioid receptors and stimulate the dopamine reward system. For some people, this increased dopamine release can cause them to seek out this feeling again and again.5
The brain and opioid use
Heroin and prescription pain relievers are exogenous opioids. When they bind to mu opioid receptors in the brain, the resulting dopamine release can be 2–10 times greater than the dopamine release associated with natural pleasures. This excess of dopamine has a powerful reinforcing effect on the brain, which is why opioids have a high potential for abuse.1
The brain and chronic opioid use
Tolerance develops with chronic opioid use. With repeated exposure, opioid receptors become less responsive to opioid stimulation. More opioid is needed to stimulate the reward system to release the same amount of dopamine and produce the same amount of pleasure as before. The cortex sends inhibitory signals to the limbic system to stop an individual from self-destructive behaviors.6 Over time, the limbic system communicates to the cortex that opioid use is important,6 making an individual who is dependent on opioids physically less capable of choosing to avoid risky behaviors.3,7 When an individual who is physically dependent on opioids suddenly stops using, they experience withdrawal symptoms.6
Treating Dependence with Medication
Agonist therapy
Agonists bind to the mu receptor and fully activate the dopamine reward system so that the patient does not experience withdrawal symptoms. Agonists work similarly to illicit opioids and prescription pain relievers.8
Partial agonist therapy
Partial agonists bind to mu opioid receptors, blocking them from other opioids and partially activating them.9 Because they don’t fully activate the opioid receptors, they produce a more limited response than full agonists.10
Antagonist therapy
Opioid antagonists bind to mu opioid receptors in the brain, blocking the receptor from opioids. Antagonists do not activate the mu opioid receptor, so there is no excessive stimulation of the dopamine reward system.6
MEDICATION-ASSISTED Treatment (MAT)
OPTIONS FOR OPIOID DEPENDENCE1, 6, 8, 9, 15–18
| AGONIST THERAPY |
PARTIAL AGONIST THERAPY |
ANTAGONIST THERAPY |
|
|---|---|---|---|
| Binds to µ opioid receptor | YES | YES | YES |
| Activates µ opioid receptor to release dopamine | YES | YES but not to the extent of a full agonist |
NO |
| Administration | Daily oral concentration | Daily sublingual film, sublingual tablet, buccal film, or six-month subdermal implant | Daily oral medication or monthly intramuscular injection |
| Setting | Provided at certified opioid treatment program settings | Sublingual film, sublingual tablet, or buccal film can be initially provided in a physician's office then as a take-home medication. The six-month subdermal implant requires HCP administration | Daily oral can be provided as take-home medication. Monthly injection requires HCP administration. |
| DEA schedule | Schedule II controlled substance | Schedule III controlled substance | Not scheduled |
| Requires detox | NO | NO | YES |
| Requires counseling | YES | YES | YES |
This chart is not intended to make any product comparisons. There are no head-to-head clinical studies between products in the different classes and no comparisons of safety or efficacy of any products are to be made.
VIVITROL is not right for everyone. There are significant risks from VIVITROL treatment, including risk of opioid overdose, injection site reactions and sudden opioid withdrawal.
See Important Safety Information below. Discuss all benefits and risks with your patients. See Prescribing Information. Review Medication Guide with your patients.
