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30 Cards in this Set

  • Front
  • Back
What's an opiate? What's an opioid?
Opiates are the naturally ocurring narcotic alkaloids found in the opium poppy plant (Papaver somniferum). The opiates are morphine, codeine, papaverine, and thebaine.

An opioid is any psychoactive subtance that binds to opiod receptors.

In other words, all opiates are opioids but not all opioids are opiates.
Name four opiates:
Morphine
Codeine
Papaverine
Thebaine

Only a small amount of thebaine is present in opium poppies
What is opium?
Opium is the dried latex attained from the opium poppy (Papaver somniferum)
What is narcosis?
A state of stupor or drowsiness
What is the scientific name for the opium poppy?
Papaver somniferum ("sleep-bringing poppy")
What is latex? What is the biological role of latex?
Latex is a milky fluid found in 10% of all plants.

It serves a defense function, containing high concentrations of toxic substances that discourage herbivores from eating the plant.
What is Oxycontin?
Oxycontin is the trade name for a time-released formula of oxycodone, a semi-synthetic analgesic opioid.
Which opiate is oxycodone derived from?

What is the trade name for oxycodone?
Oxycodone is a semi-synthetic derivatie of thebaine, a naturally ocurring opiate. It has strong opioid analgesic properties.

The trade name for a popular time-released formula of oxycodone is Oxycontin.

The trade name of a combination formula of oxycodone and paracetamol is Percocet.
What is Dilaudid?
Dilaudid is the trade name for hydromorphone, a semi-synthetic opioid analgesic dervied from morphine.
What is Percocet?
Percocet is the trade name of a drug that contains a combination of oxycodone and paracetamol.
What is Demerol?
Demerol is the trade name for pethidine, also called meperidine, a synthetic opioid analgesic.
What is pethidine?

What's another name for pethidine?

What is the trade name for pethidine?
Pethidine is a totally synthetic opioid analgesic. It is also called meperidine.

The trade name for pethidine is Demerol.
What is heroin?
Heroin is diacetylmorphine, a semi-synthetic derivative of morphine. It is a morphine pro-drug quickly converted to morphine by hepatic metabolism.
What is hydrocodone?

What is the trade name for hydrocodone?
Hydrocodone is a synthetic opioid analgesic derived from the opiates codeine and thebaine

Hydrocodone is sold in a combination formula with paracetamol known as Vicodin.
What is naloxone?
Opiod receptor antagonist
What are the three principal classes of opioid receptors?
μ, κ, δ (mu, kappa, and delta)
What is laudanum?
Laudanum, also known as Tincture of Opium, is a preparation containing 10% powdered opium.

As powdered opium it contains all the opiates, including morphine, codeine, papaverine, and thebaine.
What is nepenthe?
Nepenthe is a medicine for sorrow mentioned in ancient Greek literature and mythology, inluding Homer's Odyssey.

In ancient Greek, nepenthe means "that which chases away sorrow."

Nepenthe is thought by some scholars to have been an opium preparation similar to laudanum.
What is fentanyl?
Fentanyl is a potent synthetic opioid analgesic and anesthetic.
What structures does the mesolimbic dopaminergic pathway run through?
The mesolimbic pathway begins in the ventral tegmental area (VTA) of the midbrain and connects to limbic system through the nucleus accumbens (NA) located in the ventral striatum.

*Note, the NA is located in the ventral striatum
In a broad sense, what kind of receptors are opioid receptors?
Opioid receptors are metabotropic receptors. Specifically, they are G-protein coupled receptors that are indirectly linked (through the cyclic AMP second messenger system) to potassium (K+) ion channels.

Activation of opioid receptors blocks these K+ channels from opening, thus inhibiting depolarization.
If opioids discourage action potentials through blocking K+ channels from opening, how do they lead to INCREASED dopamine release in the mesolimbic pathway?
It's simpler than you think.

Opioids have an inhibitory effect on the neuron that they bind to. If the neuron that they bind to is a GABAergic neuron, then the opioid will have the effect of "inhibiting the inhibitor."

Thus opiods increase dopamine transmission by inhibiting those neurons that would inhibit dopamine transmission.
Where is the nucleus accumbens (NA) located?
Located in the ventral striatum. Okay, but where is this?

*Note that the ventral striatum is no the same as the ventral tegmental area
Where is the ventral tegmental area (VTA) located?
The ventral tegmental area (VTA) is located on the floor, near the midline, of the midbrain.
Describe the organic mechanism that accounts for the euphoric effects of opiods:
The euphoric effects of opioids result from increased synaptic levels of dopamine in the mesolimbic pathway.

Opiods increase dopamine levels by inhibiting GABAergic neurons that would otherwise inhibit the dopaminergic neurons of this pathway (The GABAergic neurons inhibited by opiods have a lot of mu receptors and are thus susceptible to this inhibition).

Euphoria only occurs when the rate of change in dopamine levels occurs quickly with a corresponding burst in NA activity. Slow build-up does not result in euphoria or "high."
What is the classic triad of symptoms that constitutes the opioid overdose toxidrome?

What other features are seen?
1) Decreased level of consciousness (stupor or coma)

2) Respiratory depression

3) Miosis

Also seen: bradycardia, hypothermia

The miosis can change to the opposite when brain conditions become anoxic, right?
Which drug is used as an antidote for opiod overdose? How does it work?
Naloxone (trade name Narcan)

*How does it work?

*Note: Don't confuse naloxone with naltrexone.
Describe the opioid withdrawal syndrome:
Think of it this way:
Reversal of euphoria and sedation/hypnosis

Rebound activity of nucleus ceruleus (increased NA)

Reversal of gastrointestinal symptoms

To meet DSM criteria you must have 3 of the following:

Vital signs:
Fever

Psychiatric symptoms:
-Insomina
-Dysphoric mood

Nervous system:
-Lacrimation or rhinorrhea
-Pupillary dilation, piloerection, sweating

GI system
-Nausea/vomiting
-Diarrhea

MSK system:
Muscle aches
What accounts for the sympathetic syndrome seen in opioid withdrawal?
Opioids inhibit the nucleus ceruleus, a nucleus in the pons important in the synthesis of noradrenaline for the CNS.

When opiates are withdrawn, rebound hyperactivity of noradrenergic neurons in the locus ceruleus increases levels of NA and result in the sympathetic syndrome seen in opioid withdrawal.
Where is the locus ceruleus?

What effect do opioids have on the locus ceruleus?
The locus ceruleus in a nucleus located in the pons. Neurons in the locus ceruleus are the principle synthesizers of noradrenaline in the brain.

Opioids inhibit the locus ceruleus.