Opioids Flashcards
Examples of opiates
Codeine
Morphine
Heroin
How can you get morphine from codeine?
Codeine can be metabolised to morphine by CYP2D6
Examples of therapeutic opioids
Codeine
Fentanyl
Morphine
What are the uses of therapeutic opioids
- Analgesia
- Antitussive (cough suppression)
- anti-diarrhoea
- anaesthetic
- palliation
Outline the onset + duration of fentanyl compared to morphine
- fentanyl: fast onset + short duration
- morphine: slow onset + long duration
What are the adverse drug reactions of therapeutic opioids
- constipation
- drowsiness
- dysphoria
- flushing + headache
- hyperhidrosis
- miosis
- nausea
- respiratory depression
- itching
- urinary retention
What are contraindications of therapeutic opioids?
- head injury or raised ICP
- depression
- asthmatics
- pregnancy
- paralytic ileus
What are important drug drug reactions of therapeutic opioids?
- CNS depressants e.g. AEDs + benzos
- other opioid containing drugs
- drugs that reduce gut motility
- CYP450 inhibitors
What drug is used to opioid overdose?
How does it work?
Naloxone
Competitive opioid receptor antagonist
What opioids are used in used disorder?
Buprenorphine
Methadone
Signs of opioid overdose
- Pinpoint pupils
- blue lips + fingertips
- bradycardia, weak pulse or hypotension
- slow, irregular breathing
- not waking up or responding to voice/touch
What is the mechanism of action of buprenorphine in use disorder?
- Partial agonist of µ receptors
- activate them but to a lower extent than full agonists
- produces enough opioid effect to alleviate withdrawal symptoms but with less euphoria than full agonsits
- Relatively long action
What is the mechanism of action of methadone in use disorder?
- full agonsits for µ receptors > alleviates withdrawal symptoms of opioid dependence
- but more lipophilic than morphine so longer duration of action
What opiate is a metabolite of codeine?
Morphine
What stimulates people to keep taking opioids beyond analgesic benefits?
- Release of dopamine > euphoric feeling
- addiction + dependence
How do opioids produce their analgesic effect?
(Mechanism of action)
- bind to µ receptors
- inhibits pain signal transmission by blocking neurotransmitter release
- reducing perception of pain > analgesic affect
Order fentanyl, buprenorphine, morphine + codeine in terms of protency from most to least
- fentanyl
- buprenorphine
- morphine
- codeine
Why may additional doses of naloxone need to be administered after a period of time
- Rapid distribution - duration only 30-60
- Antagonistic affects may wear off before opioid has been cleared
What is opioid dependence?
Need to keep taking opioids at higher doses to feel normal (not even to have analgesic or euphoric feeling)
What are classes of drugs assigned based on?
What is the scale
Harmfulness attributed to drug when it is misused
A-C
Describe drug schedules
- dictates how drug is produced, stored, how prescribed + what records need to be kept
- schedule 1: drugs not used mediciniallly
- schedule 2-5: decreasing controls + requirements
- lower the schedule, the lower potential for abuse + dependence
What class + schedule do opioids have?
Class A-C
Schedule 2,3+5
What is drug tolerance?
Higher dose of drug is needed to elicit the same response
Define opiate
Examples
Natural opioids
heroin, codeine, morphine
Where do opioids inhibit pain?
In the dorsal horn of the spinal cord
