Chapter 11: Opioids Flashcards
abstinence syndrome
Condition characterized by unpleasant symptoms when an individual tries to cease drug use; AKA withdrawal
anesthetic
General anesthetics are substances that depress the CNS, decreasing all sensations in the body and causing unconsciousness. Local anesthetics do not cause unconsciousness, but prevent pain signals by blocking Na+ channels.
buprenorphine (buprenex)
An opioid partial agonist–antagonist used in opioid treatment programs that may be substituted for methadone and yields similar treatment results; high affinity but low efficacy at the mu opioid receptor as well as antagonist activity at the k-receptor, it has weaker opioid effects and is less likely to result in overdose; has a long duration; can lead to respiratory depression and death when combined with CNS depressants
clonidine
An α2-adrenergic agonist that stimulates NE autoreceptors and inhibits noradrenergic cell firing. It is used to reduce symptoms of opioid withdrawal; reverses hyperexcitable state to relieve symptoms (chills, tearing, yawning, stomach cramps, sweating, muscle aches).
Cross-dependence
Withdrawal signs occurring in a dependent individual can be terminated by administering drugs in the same class.
cross-tolerance
Tolerance to a specific drug can reduce the effectiveness of a another drug in the same class.
δ-receptor
A type of opioid receptor primarily in the forebrain that may help regulate olfaction, motor integration, reinforcement, and cognitive function.
descending modulatory pathways
Bundles of nerve fibers originating at higher brain regions that influence lower brain or spinal cord function. One arises from the PAG in the the midbrain and influences pain signals carried by the spinal cord neurons.
detoxified
A drug user undergoing detoxification is considered to be detoxified when signs of the abstinence syndrome end.
endomorphins
Group of endogenous opioid peptides in the CNS that selectively bind to the opioid receptor, and eliminate pain.
endorphins
Group of endogneous peptides in the brain that stimulate mu and delta opioid receptors, reducing pain and enhancing one’s general mood.
k-receptor
An opioid receptor located in the striatum, amygdala, hypothalamus, and pituitary gland that may help regulate pain, perception, gut motility, dysphoria, water balance, hunger, temperature, and neuroendocrine function.
methadone
A long-acting opioid drug that may be substituted for other opioids in order to prevent withdrawal symptoms during detox; reduces symptoms to a comfortable level.
methadone maintenance program
Most effective treatment program for opioid addicts that involves the substitution of the opioid with methadone to prevent withdrawal symptoms and avoid a relapse.
μ-receptor
A subtype of opioid receptor located in the brain and spinal cord that has a high affinity for morphine and certain other opiate drugs.
multidimensional approach
Treatment that involves a combination of methods to prevent drug abuse relapse, including detoxification, pharmacological support, and counseling.
narcotic analgesics
Class of drugs originally derived from the opium poppy that reduce pain but do not cause unconsciousness. They create a feeling of relaxation and sleep in an individual, but in high doses can cause coma or death.
NOP-R
One of the four opioid receptors. It is widely distributed in the CNS and the peripheral nervous system and is activated by the neuropeptide nociceptin/orphanin FQ.
partial agonists
Drugs that bind to a receptor but have low efficacy, producing weaker biological effects than a full agonist. Hence they act as agonists at some receptors and antagonists at others, depending on the regional concentration of full agonist. These were previously called mixed agonist-antagonists.
physical dependence
Developed need for a drug, such as alcohol or opioids, by the body as a result of prolonged drug use. Termination of drug use will lead to withdrawal symptoms (abstinence).
primers
Drug-like effects caused by stress or drug-conditioned stimuli that reinstate drug use after abstinence.
pro-opiomelanocortin (POMC)
One of the four large opioid propeptide precursors that are broken down by proteases to form smaller active opioids (endorphins) in the brain.
prodynorphin
One of the four large opioid propeptide precursors that are broken down by proteases to form smaller active opioids (dynorphins) in the brain.
proenkephalin
One of the four large opioid propeptide precursors that are broken down by proteases to form smaller active opioids (enkephalins) in the brain.
pronociceptin/ orphanin FQ
One of the four large opioid propeptide precursors, that is broken down by proteases to form smaller active opioids (nociceptin, orphanin FQ) in the brain.
pure antagonist
Drug that produces no pharmacological activity (i.e., no efficacy) and that can prevent or reverse the effects of a drug agonist by occupying the receptor site.
receptor cloning
Process used to produce large amounts of identical receptor proteins in a cell line.
sensitization
Enhanced response to a particular drug after repeated drug exposure.
spinal interneurons
Nerve cells with short axons within the spinal cord.
suraspinal
Located above the spinal cord or spine
tolerance
Decreased response to a drug as a direct result of repeated drug exposure.
transfection
Process used to introduce genetic material into a cell by injecting it with a DNA sequence coding for the desired protein product.
active ingredients of opium
morphine, codeine, thebaine, narcotine,
how does codeine differ from morphine?
identical except instead of a methoxy (-OCH3) there is a hydroxyl (-OH) group; produces a drug that has less analgesic effects and fewer side effects than morpine
how does heroine differ from morphine?
the addition of two acetyl groups; mades it 2-4x more potent when injected and faster acting because the change makes it more lipid soluble –> reaches the brain more quickly
types of opioid receptors
μ (mu); δ (delta); κ (kappa); NOP-R
how is morphine usually administered?
intramuscularly or orally
how long before opioid metabolites are excreted?
most are excreted in the urine within 24 hours
low to moderate doses
pain is relieved, respiration is somewhat depressed, pupils are constricted; drowsiness, decreased sensitivity to the environment, impaired ability to concentrate, dreamy sleep, suppressed cough reflex, decreased appetite, drop in body temperature, reduced sex drive
high doses
state of euphoria, “rush,” powerful reinforcer, dysphoria, consisting of restlessness and anxiety, nausea, vomiting, effects on chemical trigger zone, unconsciousness, respiratory failure, constipation
binding curve
as opioids increase binding also increases and gradually tapers off until the receptors are fully occupied
ileum
lowest portion of the small intestine
selectivity
a given molecule readily binds to one receptor subtype and has relatively low binding affinity for the others
do opioids bind to NOP-R?
no
what brain area of mu receptors plays a role in positive reinforcement?
nucleus accumbens
what brain area of mu receptors plays a role in cardiovascular and respiratory depression, cough control, nausea and vomiting?
brainstem
what brain area of mu receptors plays a role in sensorimotor integration?
thalamus, striatum
what does k receptor have high affinity binding to?
ketocyclazocine–an opioid analog that produces hallucinations and dysphoria
what are opioid receptors linked to?
the structure of G proteins, which suggest that they mediate metabotrpoic responses
propeptides
larger peptides (precursor peptides) that are broken into smaller active opioids; there are four coded for by separate genes
types of propeptides
prodynorphin, pro-opiomelanocortin (POMC), proenkephalin, pronociceptin/orphanin FQ