Opiods Agonist/Antagonists Flashcards
3 types of Opioids class
Opioid agonist Opioid antagonist Opioid agonist-antagonists
Opioids derived from
Opium, meaning juice
Narcotic is a greek word for
Stupor
Why is opiod unique?
Produces analgesia without loss of proprioception, touch or consciousness
Bind to receptor site to elicit a response definition
Agonist
ONLY this form have an AGONIST ACTIVITY
LEVOROTATORY
Blocks agonist from binding
Antagonist
Opiod agonist-antagonists
partially bind to mu receptors produces a limited response (partial Agonist) or no effect (competitive antagonist)
SEMI SYNTHETIC OPIOIDS are (CHOO)
Codeine Heroin Hydromorphone Oxycodone
Semisynthetic opiods are
modified morphine molecule
Synthetic opiods are FSAR MMT
Fentanyl, Sufentanyl, Alfentanyl, Remifentanyl Methadone, Meperidine, Tramadol
Mechanism of action : opiods in ______State bind stroly at _______opioid receptor site
ionized; anionic
Opioid agonists and neurotransmitters
inhibit neurotransmitters pre and post synaptic
IN CNS opioid action is
Brainstem and spinal cord
IN PNS opioids on
Primary afferent neurons
Opioids on primary afferent neurons are activated by 3 endogenous peptide opioid receptor ligands which are?
Enkephalins Endorphins Dynorphins
Opiods and endogenous ligands?
they mimic the endogenous ligands
Raphe magnus ligand
Enkephalin
Periventricular nuclei and periaqueductal grey
Morphine and dynorphin
What is the principal effect of opiod receptor activation?
Decrease neurotransmission
How do opiods prevent neurotransmitter release?
Due to presynaptic inhibition of Ca2+ channels which reduce the neurotransmitter release.
Opiods block the release of these neurotransmitters (ADNSS)
Ach, Dopamine, Norepinephrine, Substance P, Serotonin
Pre-synaptic opioid receptor is a
GPCR
What is the mechanism of presynaptic activity?
Leads to a decrease in cAMP decrease in Ca2+ ion influx and inhibits the release of excitatory neurotransmitters
Excitatory neurotransmitters blocked, (2)
Glutamate Susbtance P
Post synaptic opioid receptor action
Inhibit DEPOLARIZATION of neuron by inhibiting the production of adenylate cyclase , thereby inhibiting ion channel (Na and Ca) Inactviation of K+ channels lead to hyperpolarization of the cell
All opioid receptors are
G protein coupled receptors that INHIBIT ADENYLATE CYCLASE leading to decrease in cAMP
With opiod the resting MP becomes more ______ leading to _______of neuron to propagate a signal. There is ________ neuronal activity
negative, inability; decrease
The receptors mu, kappa and delta are all
GPCR with same mechanism of action, decrease cAMP
Mu and Morphine types of anesthesia
Supra spinal spinal
Mu 1 produces analgesia with ELMUH
Euphoria, low abuse potential, miosis, URINARY RETENTION, Hypotethermia
Mu 1 and Mu 2 agonist are EMS
Endorphins Morphine Synthetic opioids
Mu 2 responsible for CHAP marked
Constipation marked, hypoventilation, analgesia (spinal) and physical dependence
Kappa receptors responsible for (low SAD MD)
Low abuse potential, SEDATION, Analgesia (s+s) DYSPHORIA, MIOSIS, DIURESIS
Kappa agonist receptors - dynorphins inhibit
N-type Ca2+ channels leading to analgesia
Kappa agonists _____Respiratory depression
Less
Kappa agonists may cause
DIURESIS and DYSPHORIA
May be resistant to analgesic effect of Kappa
High intensity painful stimulation
On which receptor does OPIOD AGONIST- ANTAGONIST act principally?
KAPPA receptors
Delta receptors responsible for (PACUVA) minimal
Physical dependence, analgesia S+S, constipation minimal, urinary retention, ventilatory depression, antidepressant
Receptor to have ONLY SPINAL anesthesia efect
Mu 2
Receptor associated with marked constipation
Mu 2
Receptors associated with urinary retention
Mu 1 and delta
Receptor associated with low abuse potential
Mu 1 and kappa
Receptor associated with SEDATION
Kappa
Receptor associated with DIURESIS and DYSPHORIA
Kappa
Receptor associated with EUPHORIA
Mu 1
Opioids receptors are in the
Brain and spinal cord
Where in the brain are opiods receptors (PACH)
Periaqueductal gray matter of brainstem, amygdala, corpus striatum, and hypothalamus
Where in the spinal cord are opiods receptors
SUBSTANTIA GELATINOSA dorsal horn
Principal receptor in spinal cord
Mu
Endorphins inhibit release of
Neurotransmitters
Opiods given Neuraxial are not associated with
SNS denervation, Skeletal muscle weakness, loss of proprioception
Epidural dose vs subarachnoid which is stronger
Epidural 5-10 times subarachnoid dose
Epidural separated by
Dura and arachnoid
Path of opiods in epidural space
Undergoes uptake in epidural fat –> systemic absorption –> diffusion across the dura into CSF
What penetrates dura faster? (solubility / molecular weight)
HIghly lipid soluble, low molecular weight.
CSF concentration of sufentanyl peaks in
6 min
CSF concentration of Fentanyl peaks in
20 min
CSF concentration of MORPHINE peaks in
1-4 hours
Spinal cord ends at
L1
What is the most common location for epidural
LUMBAR spine, (largest region)
Epidural administration of morphine, sufentanyl and fentanyl mimics
IM injection
When Epinephrine administered with opioid it
Decreases systemic absorption
Subarachnoid (Intrathecal) LIPID soluble opiods? meaning Absorption in CSF is
Fentanyl , rapid absorption in CSF
Subarachnoid (Intrathecal) WATER Soluble opiods meaning Absorption in CSF is _________, meaning may cause _____
MORPHINE , no absorption, float in CSF, may cause delayed apnea
When subarachnoid morphine and EPINEPHRINE
Increase block density Decrease intravascular absorption Prolong duration of action of lipid soluble anesthetics no effect on protein bound LA.
Side effects of Neuraxial (PNUDS CVS NeWa)
Pruritus, N/V, Urinary retention, depression of ventilation, sedation, CNS excitation, viral reactivation, sexual ocular, GI thermoregulation, water retention, neonatal morbidity.
The side effects seen with neuraxial opiods administration is caused by
opiods in CSF and in systemic circulation
Side effect of neuraxial opiods that are dose dependent PNUR
Pruritus, N/V, Urinary retention, Respiratory depression
The most common out of the side effect of neuraxial opiods? characterized by
PRURITUS Localized FUN (localized in face, upper thorax, neck)
What can neuraxial opiod related pruritus treated wtih
BUPRENEX, treat without reversing analgesia
Urinary retention with neuraxial more common with
Young males
What is the mechanism of urinary retention with neuraxial opioid?
Interaction of the opiod with sacral spinal cord PNS sacral inhibition, detrusor muscle relax, increase bladder capacity,—> ↑ retention
Morphine can cause marked detrusor relaxation in ______ can last ____
15 min 16 hours
Most serious side effect of opioid
Respiratory depression
No respiratory depression after
24 hours
What is the respiratory depression caused by ?
Cephalad migration of opioid in CSF and interaction with receptors in ventral medulla
Increase risk of respiratory depression
-Concomittant use of opiod of sedative use -High opiod use, low lipid solubility of opiod - Lack of opiod tolerance, advanced age - Increased intrathoracic pressure
Diagnosis of respiratory depression
↓ MV, ↓RR, ↓SPO2, somnolence →apnea, CP arrest