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Anticonvulsants and anxiolytics: Barbiturates
Anticonvulsants and anxiolytics: Benzodiazepines
Medications for neurodegenerative diseases
Opioid agonists, mixed agonist-antagonists and partial agonists
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Opioids: Last Week Tonight with John Oliver (HBO)
Laxatives & antidiarrheal agents
Opiates, naloxone, naltrexone
opioid analgesics p. 569
opiod analgesics p. 569
opioid effect on p. 569
opioids for p. 569
opioid withdrawal p. 590
opioid effects p. 569
opioids for withdrawal p. 569
opioids p. 570
for opioid toxicity p. 247, 569, 590
opioid toxicity p. 569, 590
Beers criteria p. 246
intoxication and withdrawal p. 590
pentazocine and p. 570
sleep apnea p. 699
toxicity treatment p. 247
opioid effect p. 569
opiate use during p. 635
with opioid analgesics p. 569
Opioid agonists are medications used mainly to control acute or chronic pain in particular situations.
Some of them are also used to treat diarrhea and cough. When treating pain, the goal should be to use short-acting opioids at the lowest effective dose for just a few days, and slowly increase their dose only as needed.
As a class, opioids share one thing in common, they bind to opioid receptors in the brain, spinal cord, and gastrointestinal tract.
Some are endogenous, meaning they are produced naturally by the body, like endorphins, short for endogenous morphine.
But others are exogenous, meaning they come from outside the body, like heroin and morphine, which come from the opium poppy; a flowering plant that oozes a milky white liquid.
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 get picked up by another neuron in the same area.
Norepinephrine and serotonin release takes place in pain processing regions of the brain like the thalamus, brainstem, and spinal cord, resulting in a decreased sensitivity to pain.
Opioid full agonists are drugs that bind to and activate opioid receptors in the body. They are used to treat pain and can also produce feelings of euphoria, which has led to their abuse and addiction potential. Examples of opioid agonists include morphine, codeine, and oxycodone.
Mixed agonist-antagonists bind to and activate opioid receptors to a certain extent, but also have the ability to block or inhibit the effects of other opioids. They can also be used to treat pain and may have a lower risk of abuse and addiction compared to full agonists.
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