Drugs Flashcards
What causes the excitatory behavior from opioids?
- hypothalamus effects
- indirect activation of dopaminergic receptors
How do opioids cause respiratory depression?
- affect medullary and pontine respiratory centers
- reduce sensitivity and change threshold for PaCO2 by chemoreceptors –> leads to CO2 retention
Is opioid-induced bracycardia responsive to atropine?
yes, vagally mediated
Which opioids are contraindicated in mast cell tumors and why?
- morphine, methadone, meperidine
- cause histamine release with marked hypotension
After epidural morphine administration how long does it take until analgesic effects start?
30 min
What is the oral transmucosal bioavailability of buprenorphine?
50%
List injectable opioids from most likely to least likely to cause vomiting
morphine > hydromorphone > methadone > fentanyl > buprenorphine > butorphanol
How may naloxone be beneficial in shock?
reduced splanchnic capacitance –> improved venous return and CO + MAP
Why is IV diazepam use discouraged compared to midazolam?
contains propylene glycol
* irritates blood vessels –> phlebitis, thrombosis
* propylene glycol toxicity from prolonged administraiton –> metabolic acidosis, hyperosmolality, neurologic abnormalities, organ dysfunction
What is the MOA of alpha-2 agonists?
Gi/o G-protein-couple receptor binding –> inhibits adenylyl cycle –> decrased cAMP –>
stimulates K-channels and NaH exchange, inhibits Ca++ channels
inhibits release of norepinephrine
What part of the brain do alpha-2 agoists affect?
locus ceruleus (brainstem)
How do alpha-2 agonists affect blood flow in the following tissues?
- brain
- heart
- kidneys
- skin
- muscles
- intestines
- brain»_space; decreased cerebral blood flow - can cause hypoxia
- heart, kidneys»_space; preserved
- skin, muscles, intestines»_space; decreased
What can be coadministered to reduce cardiovascular side effects of alpha-2 agonists?
Ca+ channel blockers
How do alpha-2 agonists cause hyperglycemia?
bind to alpha-adrenoreceptors on the beta cells of the islets of Langerhans –> inhibits insulin release
increase growth hormone release
How do alpha-2 agonists cause diuresis?
- inhibit ADH release
- inhibit ADH’s effect on collecting ducts
- inhibit release of renin
- increase release of atrial natriuretic factor
What other receptors do alpha-2 agonists bind to?
Imidazoline receptors
What is the function of the COX 1 pathway?
- hemostasis
- renal perfusion
- gastric mucous and bicarbonate secretion
Where are COX-3 located and what are 2 NSAIDs that cause COX-3 inhibition?
cerebral cortex
inhibition decreases prostaglandin E2 synthesis
acetaminophen and metamizole
How are NSAIDs metabolized and excreted?
- cytochrome P450 enzyme
- glucuronidation or oxidation
- excreted via biliary route and urien
How does gastric NSAID injury differ to intestinal NSAID injury?
gastrc: decreased bicarbonate secretion and mucus production
intestines: enterohepatic recylcing and consequent prolonged and repeated exposure
How do COX1 and COX2 differ in their hemostatic effects?
COX 1 –> TXA –> PLT aggregation and vasoconstriction
COX 2 –> prostacyclin –> anticoagulant and vasodilation
What is the mechanism of action of Grapiprant?
EP4 prostaglandin receptor antagonist
What are clinical signs of methemoglobinemia?
- cyanosis
- facial edema
- prolapsed conjunctival membranes
- brown blood and urine
- tachypnea and dyspnea
What is the mechanism of action of Gabapentin?
presynaptic alpha2-delta1 subunit inhibition of the Ca-channel –> leads to decreased neurotransmitter release
What is the mechanism of action of Tramadol?
mu-agonist via its metabolite M1 (cytochrome P450 pathway)
some norepinephrine and serotonin reuptake inhibition
What is the MOA of trazodone
- serotonin reuptake inhibitor
- antagonist of 5HT2A and 5HT2C
- inhibits serotonin transporter and serotonin type 2 receptor
- additionally: H1, alpha-1, and T-type Ca channel blocker
Why is trazodone contraindicated in glaucoma patients?
mydriasis –> can trigger acute crisis
