Term
| What are the endogenous opiate peptides and their receptors? What is their purpose and action? Which is most important? |
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Definition
1. *Endorphins→μ
2. Enkephalins→δ
3. Dynorphins→κ
-They are released from interneurons in the CNS to inhibit mostly **NE and *Substance P release by acting on the *Gi coupled receptors above, producing *analgesia
-μ is the one that has the most pharmacology
-The NE inhibition is most important and causes a net drop in SANS tone leading to the stereotypical sign of opiate use ***MIOSIS (pin hole pupils) |
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Term
| What kind of analgesia do opiates produce? |
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Definition
| -Dissociative; means hallucination will be common (similar to ketamine)→ leads to abuse |
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Term
| What is the relation between opiates and respiration? Treatment? |
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Definition
-Major CNS respiratory center (senses ↑CO2) has μ receptors and is cut off leaving the job to the minor peripheral centers (sense ↓O2)
-Also, through CNS depression, we get resp. depression
-Together this means if we have a patient comes in with respiratory depression from opiate overdose we **DO NOT GIVE 02→will stop their breathing
-Treat instead with **naloxone |
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Term
| What about opiates and cardio? |
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Definition
-They don't effect the heart, but hypersensitivity causes **histamine release which *vasodilates
-Contraindication in **head injuries (ICP increase) |
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Term
| What effects do opiates have through different receptors other than μ? |
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Definition
-Cough suppression
-Nausea and vomiting (D2 receptors in chemoreceptor trigger zone) |
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Term
| In addition to those stated what effects does morphine have? Treatment? Elimination? |
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Definition
SMOOTH MUCLES;
Long muscle relaxation and circular muscle constriction;
1. Constipation AND cramping
2. Urinary retention AND urgency
3. ↑Biliary pressure→ contraindication with gall stones
-Can treat with *M blockers (atropine-like)
-Morphine undergoes glucuronidation→**Morphine-6-glucuronide (*HIGHLY active, renal excretion)
-Means patients with renal disease will accumulate this potent metabolite |
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Term
| Give the other full μ agonists? |
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Definition
1. Meperidine; analgesic
-Anti-M; so **no miosis or GI/urinary/gall bladder effects
-Anti-M; so **tachycardia
-P450→Normeperidine (an SSRI)→*serotonin syndromes
2. Methadone; for opiate addicts
-Slow metabolism and action (1-3 days)
3. Codeine; *cough suppressant & analgesic
-Very weak agonist, but still able to be abused
-Used in combo with NSAIDs
-Hydrocodone (in vicodan) is a derivative, as well as oxycodone (both of which are frequently **abused) |
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Term
| The other opiates are mostly involved in withdrawal treatment/interactions. Reference chart on 157. |
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Definition
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Term
| What is the classic triad for acute opiate toxicity? Treatment? |
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Definition
1. Pinpoint pupils (except meperidine)
2. Respiratory depression
3. Coma
-Naloxone (a μ antagonist) |
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Term
| What is special about the tolerance to opiates? |
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Definition
-Instead of desensitizing or down-regulating the receptor (Gi coupled), the cells just ↑cAMP production
-Type of pharmacodynamic tolerance (see 157)
-However, the miosis and constipation do not decrease (means we have to increase the M-blockers right along with the morphine in cancer patients, etc.) |
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Term
| Withdrawal from opiates? Treatment? |
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Definition
-See 157
-Clonidine (blocks SANS) and methadone (slow agonist) to treat |
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Term
| What is the opiate-related cough medicine that kids drink to hallucinate? What can a bad result be? |
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Definition
-Dextremethorphan ("Going on dextro" lol)
-Similar action to ketamine
-Status epilepticus |
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Term
| And what's the concrete maker? |
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Definition
| -Loperamide; for diarrhea |
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