Opioids Flashcards
What types of forensic cases involve the behavioural effects of opioids?
Death investigations
Homicides
Drug impaired driving
Sexual assaults
How are opioids classified?
According to their effect at opioid receptors
Unrelated to chemical structure
When was morphine first extracted from the opium poppy?
1800s
What was the extraction of morphine from the opium poppy a milestone in pharmacology?
First time the active ingredient of a medicinal plant was isolated
What are the 3 types of opioids?
Naturally occurring
Semi-synthetic
Synthetic
Give examples of naturally occurring opioids
Morphine
Codeine
Give examples of semi-synthetic opioids
Hydromorphone
Oxycodone
Give examples of synthetic opioids
Methadone
Fentanyl
Give a general description of opiods and their abuse potential
Useful analgesic drugs
Issues occur due to high potential for abuse
Chronic use leads to tolerance
Describe opioid antagonists
Pure anatgonists are structurally similar but have no efficacy
They can prevent or reverse the effect of opioids
Give examples of pure opioid antagonists
Naloxone - standard care
Nalorphine
What are the therapeutic effects of opioids?
Pain relief
Cough suppression
Antidiarrheal
What are the short-term sensations of opioids?
Pain relief
Warm sensation through skin and body
Feeling of heaviness in arms and legs
Drowsiness
Relaxation
Sense of well being
What do the recreational effects of opioids depend on?
Specific opioid
Dose
Route of administration
Tolerance
What are the possible administration routes of opioids?
IV
Smoking
Insufflation
Oral ingestion
What are the three classic opioid receptors? What type are they?
Mu
Delta
Kappa
All G-protein coupled receptors
Which receptors do clinically used opioids have highest affinity for?
Most at mu-opioid receptors and less at delta- and kappa-opioid receptors
But may produce some effects at the other receptor types at higher doses
Give examples of opioids which are full-agonists at mu receptors and weak agonisty activity at delta and kappa receptors.
Morphine
Heroine
Fentanyl
Codeine
What happens when opioids bind to opioid receptors?
Increase potassium conductance
Inhibit calcium conductance
What happens when potassium conductance is increased?
Neurons are less likely to fire an action potential
What happens when calcium conductance is inhibited?
Makes a neuron less likely to release neurotransmitters
What do opioid receptor effects depend on? Give an example.
Depends on where the receptors are found.
When opioid receptors in neurons in spinal cord that carry info about pain are activated, it can inhibit transmission of pain info to brain
Which opioid receptor effects are considered the most important for analgesic and euphoric effects?
Effect on mu receptors
Describe the mechanism of reinforcement for opioids.
Opiods act via GABA-inhibitory interneurons of ventral tegmental area
By axctivating mu receptors, exogenous opioids reduce amount of GABA released
Usually, GAVA reduces the amount of DA released in nucleus accumbens
By reducing GABA, the opioids can increase the amount of DA produced and the feeling of euphoria
How strong are opioids? Give an example
Different opioids have different strengths.
Codeine often perscribed after minor dental work, fentanyl only for chronic pain conditions in patients already tolerant to opioids
When was heroin first synthesized from morphine?
1800s
How was heroin marketed?
First nonaddictive opioid to treat coughs and asthma
How is heroin synthesized?
By adding to acetyl groups to morphine.
What do the acetyl groups of heroin do?
Make it more lipid-soluble
Why is heroin much more potent than morphine when injected?
Due to its lipid-solubility, heroin reaches the brain faster
Describe heroin metabolism
Heroin
6-monacetylmorpgine
Morphine
What is fentanyl?
Fast acting, synthetic opioid
Describe clinical uses of fentanyl.
Used to pre-medicate prior to surgery
Treatment of chronic severe pain by slow release patches
What is unique to fentanyl?
Skin absorption
How is fentanyl available
Prescription (pain patches)
Hospital treatment (injectibles)
Powder
Fentanyl analogues
Counterfeit pharamceuticals
Why are transdermal fentanyl patches suitable?
Low molecular weight
High lipid solubiility
High pootency
How can fentanyl patches be used/misused
Therapeutic
Excessive use
Chewing
IV
Smoking
Fentanyl tea
What are the two types of fentanyl patches?
Reservoir patch
Matrix patch
What is a reservoir fentanyl patch?
Drug dissolved in gel with ethanol
Rate-limiting membrane
What is a matrix fentanyl patch?
Drug is suspended in a solid silicone adhesive matrix
What is methadone?
Long acting, synthetic opioid
What is meant by methadone being equipotent to morphine?
Longer acting
What is methadone used for clinically?
Treatment for heroin addiction
How is methadone used to treat heroine addiction?
Orally adminisered
Reduces drug-seeking behaviour
Suppresses withdrawal symptoms
What is doda?
Powder from ground up poppy pods, used to make tea
“Poor man’s heroin”
What are the effects of doda?
Similar, milder effects as other opioids
Ex. relaxation, calmness
Is doda legal?
For years existed in grey area
Now illegal under controlled drugs and substances act
