M6 L1 Narcotics Flashcards
2 classifications of analgesics
- narcotic (opioids)
- non-narcotic (antipyretics)
4 types of opioids
- endogenous
- plant alkaloids
- semisynthetic
- synthetic
3 ex of endogenous opioids (less important to remember)
endorphins, enkephalins, dynorphins
2 ex of plant alkaloids opioids
morphine, codeine
3 ex of semisynthetic opioids
heroin, hydromorphone (common pain killer), buprenorphine
what are classified as natural opioids
- endogenous
- plant alkaloids
2 ex of synthetic opioids
methadone, pentazocine
how do opioids work?
- bind to specific receptors in the CNS and other tissues
what are opioid receptors
- G-protein coupled receptors
Types:
1. delta (δ) (1 and 2)
2. kappa (κ) (1, 2, 3)
3. mu (μ) (1, 2, 3)
mu receptors (μ)
- analgesia
- respiratory depression **(can kill pt w overdose)
- sedation
- euphoria
- meiosis
- reduced GI motility
- physical dependence
delta receptors (δ)
- analgesia
- respiratory depression **(can kill pt w overdose)
- affective behaviour
- reinforcing actions
- reduced GI motility
kappa receptors (κ)
- analgesia
- respiratory depression **(can kill pt w overdose)
- sedation
- dysphoria (pt won’t enjoy this) and hallucinations
- meiosis
- physical dependence
desirable effects of opioids
- analgesia (can help w severe pain)
- sedation
- antitussive (especially of codeine, suppresses dry cough)
sometimes desirable effects of opioids
- constipation (w diarrhea it would b good)
- hypotension
undesirable effects of opioids
- nausea/vomiting
- respiratory depression
- mental clouding, confusion -> coma
- tolerance
- addiction
- physical dependence
when would you use opioids?
- treatment of pain (analgesic effect)
- anxiety
- dry cough (codeine)
- diarrhea (opium only)
- opioid dependence (methadone and buprenorphine)
why are opioids good as analgesics
- strongest known
- act on mu and kappa receptors mainly
- variable dose w no upper limit
only use in: SEVERE pain
- acute (post-operative)
- chronic (palliative care, when dependence is not the main concern)
most annoying adverse effect: constipation*
gradual stoppage of drug to avoid withdrawal manifestations
how do opioids work as pain killers?
2 main ways of attacks:
- Local Attacks
- sensory nerves, they attack presynaptic neurons of the neurotransmitters involved in the pain process
- block effect of any released transmitter in the postsynaptic neurons - Central Attacks on CNS
- inhibit pathways to block pain input, bc they are activated by opioids
- if still pain happening if works on how it will receive pain by acting on the limbic system of the brain (emotions, memory, behaviour, etc)
opioid tolerance
body will adapt to opioids -> decreased drug potency -> higher dose is needed to obtain same analgesic effect
cross tolerance
tolerance to an opioid (ex: morphine) -> you’d also develop tolerance to other opioids (meperidine)
addiction to opioids
physiological attachment to certain effects of opioids -> compulsive repeated use
opioid physical dependence
develop opioid withdrawal syndrome after:
- stopping of drug
- administration of opioid antagonist
what are some opioid withdrawal syndrome
- CNS stim
- tachypnea
- tachycardia & hypertension
- severe flulike illness
- yawning, lacrimation, diarrhea
- abdominal cramping, leg cramping
- tremors and muscle twitching
- piloerection
- dilated pupils
opioid antagonist
antagonist: naloxone
mixed agonists/antagonists: pentazocine
what is naloxone
- competitive opioid inhibitor
- has no analgesic effect
- causes withdrawal symptoms (so use in combo w other drugs)
- antidote for opioid drug overdose
diagnosis and treatment of opioid dependence - should always be available when opioids are being used thru IV
what is pentazocine
- has agonist action (analgesia)
- has weak antagonist action
- if used w opioid agonists (morphine) -> can induce withdrawal sympt
- activates kappa but blocks mu receptors
drug therapy of dependence for:
methadone or buprenorphine
- same opioid effect -> prevent withdrawal manifestations
- much less dependence
(now pt is dependent, but better to b dependent on this than a stronger opioid (ex: heroin) then you let the amount of this decrease to cause pt to not be dependent)
drug therapy of dependence: naloxone
- opioid antagonistic effect
- blocks drug-seeking behaviour
how does buprenorphine work to stop opioid dependence?
- act on mu not kappa receptors
- buprenorphine will take the place the morphine, like musical chairs (competitive inhibition)
- buprenorphine blocks opioids as it dissipates
what is heroin (agonist or antagonist)
full agonist
what is buprenorphine (agonist or antagonist)
partial agonist
what is naloxone? (agonist or antagonist)
antagonist
how does acute opioid toxicity appear (mild/early)
- pinpoint pupils
- hypothermia
- hypoflexia (flaccid muscles)
- hypotension and bradycardia
- respiratory depression
how does acute opioid toxicity appear (severe/late)
- severe respiratory depression -> respiratory arrest
- severe cardiovascular depression
- seizures
- coma
Acute Opioid Toxicity (CPR-3H)
Coma
Pin point pupil
Respiratory depression
Hypotension
Hypothermia
Hyporeflexia
treatment for acute opioid toxicity
naloxone (antidote)
- reverses toxic manifestations
- shorter half-life, repeat dose
- general supportive measures
