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Definition
Natural alkaloid from Papaver somniferum.
Acts primarily at m receptors (some k).
Rapid tolerance development.
Agent by which all other opioid agonists are judged (activity set at “1”).
Used mainly for it’s analgesic properties.
Recent resurgence in the use of morphine over other agents for pain control. |
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Definition
Diacetylmorphine.
Semisynthetic, and easily prepared from morphine.
Approximately twice as potent as morphine, but much more lipid-soluble.
Enters CNS rapidly, causing quick euphoria.
Not approved for clinical use due to high addiction liability. |
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Definition
Only one tenth the analgesic potency of morphine.
Little risk of addiction or respiratory depression.
Partially converted to morphine in the body, which is thought to account for the analgesic component.
Potent antitussive in the parent form. |
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Definition
Approximately twice as potent as morphine as an analgesic.
High euphoric liability.
Available in a 160 mg. extended release tablet, which is widely abused (“Hillbilly Heroin”).
Many deaths linked to chewing the extended release form. |
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Term
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Definition
Very potent synthetic morphine analgesic congener (5X).
Less constipating and longer lasting. |
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Definition
| A dextro-rotary isomer, which means it has no analgesic activity, but is an effective antitussive. |
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Definition
Most widely used synthetic congener.
Only one-tenth the mg. potency of morphine as an analgesic, and has a shorter duration of action.
Frequently abused since it does not cause miosis, and is hard to detect.
Metabolized to Normeperidine, a CNS stimulant. Decreased renal function can allow metabolite build-up, and potential seizures.
Contraindicated with MAOI therapy. |
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Term
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Definition
Same analgesic potency as morphine.
Causes much less sedation than morphine.
Longer duration of action, due to slower elimination. This explains its use to counter withdrawal symptoms. |
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Term
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Definition
Structurally related to Methadone, but less than one-tenth as potent per mg.
Properties similar to other Opioid analgesics.
Questions have been raised concerning it’s benefit in dose strengths found in most products. |
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Term
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Definition
Chemically related to Meperidine.
Approximately 80X as potent an analgesic as Morphine (similar potency among it’s other effects also).
Main advantage is it’s short half-life of redistribution (12.5 min.).
Often combined with other agents for anesthesia such as neuroleptics.
Sufentanil (Sufenta) (800X), Remifentanil (Ultiva) (80X), and Alfentanil (Alfenta) (20X) have similar uses.
Used also for continuous epidural and transdermal analgesia. |
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Term
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Definition
Selective m-receptor agonist.
Differs from other fentanyl derivatives by having an ester-linkage.
Causes short duration of action due to hydrolysis by non-specific esterases.
This allows an agent of short duration that can be more carefully titrated to needs and allows rapid recovery |
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Definition
Veterinary-use only
1000X morphine potency
Used as a large animal immobilizer (elephants)
Toxic to humans, one drop on skin can be fatal |
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Term
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Definition
| Naloxone (Narcan) is a pure antagonist normally given IV |
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Definition
| Naltrexone (Trexan) is similar, but has a longer half-life, and can be given orally (Nalmefene (Revex) too). |
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Definition
Buprenorphine (Buprenex) shares structural components of Codeine and Naltrexone.
Binds to m receptors, and elicits a weaker maximal response than other agonists.
Therefore it has less abuse potential, and has been used to counteract Heroin and Morphine addiction without causing full-blown withdrawal symptoms.
patial opioid agonist |
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Term
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Definition
Nallorphine (Nalline) is a m receptor antagonist and a weak agonist at k receptors.
While it blocks m receptor-mediated analgesia and euphoria, it also stimulates k induced analgesia and sedation.
Large doses may cause dysphoria and hallucinations.
Pentazocine (Talwin) and Nalbuphine (Nubain) have similar actions, but are stronger k mediated analgesics.
mixed opioid antagonist/ agonist |
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Term
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Definition
Newer analgesic with structural similarities to Opioids and NSAIDs.
Both the parent compound and an active metabolite have weak affinity for m receptors, however, their analgesic effect is not entirely reversed by Naloxone.
Also acts to block re-uptake of serotonin and norepinephrine in central synapses, which then decreases pain information transmission in the brain.
Analgesic strength similar to Codeine-Acetaminophen agents.
Can cause dizziness, sedation, seizures and hallucinations |
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