USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 40-year-old intravenous drug user presents with severe hypoventilation, miosis, and vomiting presents at the emergency department. Which of the following is the appropriate management in this patient?
Content Reviewers:Yifan Xiao, MD
To understand how opioids work, let’s zoom into a region of the brain tissue that has opioid receptors.
Normally, in the absence of endorphins, inhibitory neurons secrete a neurotransmitter called gamma-aminobutyric acid, or GABA, that prevents nearby neurons from releasing neurotransmitters like dopamine, serotonin, and norepinephrine.
Now, let’s say someone goes to play a rigorous game of badminton. Exercise releases endorphins which activate the three major opioid receptors located on the inhibitory neurons, called the mu, kappa, and delta receptors.
As endorphins bind to these receptors, they block the inhibitory neuron from releasing GABA, allowing the dopamine, serotonin, and norepinephrine secreting neurons to freely unload their neurotransmitters, which then gets picked up by another neuron in the same area.
However, there are also opioid receptors throughout our body, like in the gastrointestinal tract.
So, when a person receives a dose of morphine, it could also result in a series of unwanted side effects, like nausea, vomiting, and constipation.
However, the most dangerous side effect is respiratory depression caused by stimulation of the respiratory centers located in the medulla.
This happens when a person overdoses on an opioid like morphine or heroin.
Respiratory depression can be life-threatening and should be treated right away - because the person can literally stop breathing.
These medications bind strongly to opioid receptors without activating them.
Since opioids are binding and unbinding to receptors constantly, once an opioid releases its hold on a receptor, naloxone can simply sneak in and bind more strongly.
Naloxone has a rapid onset and short duration of action of 1 to 2 hours.
So when it’s given intravenously, it can reverse the effects of opioids within minutes, potentially saving a person’s life.
Naloxone can also reverse this effect and save the baby’s life.
Another use of naloxone is to detect when a person is opioid dependent.
A person who is a chronic user of opioids like morphine or heroin can develop tolerance.
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