Drug Action 4 Flashcards
What is BRL37344 used to treat?
Obesity
What is phenylephrine used to treat?
Nasal decongestant
What is clonidine used to treat?
Hypertension
What is BRL37344 an agonist of?
ADR beta 3
Name one selective agonist for ADR beta 3.
BRL37344
What is prazocin used to treat?
Hypertension
What is yohimbine used to treat?
Erectile dysfunction
What is propanolol used to treat?
Angina, cardiac dysrhythmia, hypertension
What receptors regulate NA release?
Presynaptic receptors on postganglionic SS varcosities regulate the release of NA
What pre-synaptic neural connection negatively modulates NA synapses?
ACh
What pre-synaptic neural connection negatively modulates ACh synapses?
NA
What is released from smooth muscle that negatively modulates the NA neuron innervating it?
PG
What is released from endothelial cells that negatively modulates the ACh neuron that innervates them?
NO
What does NANC stand for?
Non-adrenergic, non-cholinergic NT
What NANC NTs are in the ANS?
5-HT, ATP, peptides, NO
Name three NANC peptides.
VIP, somatostatin, substance-P
What does VIP stand for?
Vasoactive intestinal polypeptide
Why can NANC NTs be referred to as co-transmitters?
They are released alongside ACh and ADR NTs to modulate the response chemically
What principle does NO break, and why?
Dale’s principle - synthesised outside the nerve terminal
What is NO synthesized from?
O2 and L-arginine
What synthesises NO?
NOS
What does NOS stand for?
Nitrogen oxide synthase
What does eNOS stand for?
Endothelia
What does nNOS stand for?
NANC
Where is eNOS found?
Endothelia
Where is nNOS found?
NANC nerves
What does activation of NOS result in?
Increased cGMP - decreased IC Ca - increased K channel - hyperpolarization - relaxation
What terminates the action of NO?
Phosphodiesterase V
How is the action of NO terminated?
Break down of cGMP by phosphodiesterase V
How does phosphodiesterase V terminate NO action?
Breaks down cGMP
What is the MOA of sildenafil?
Selective inhibitor of phosphodiesterase V
What is sildenafil also known as?
Viagra
What are the unwanted side effects of sildenafil?
Hypotension, flushing, headache, visual disturbance
When was the first compound for migraine treatment discovered?
1868
What did the first migraine treatment contain?
Ergotamine
What was the first compound for migraine treatment?
Ergot
When were the triptans developed?
20th Century
What is the incidence of migraines?
1-2%
What are the two clinical sub-types of migraine?
With or without aura
What is the general treatment strategy for migraines?
All patients require acute treatment, frequent attacks require prophylactic pharmacology
What is the socioeconomic cost of migraines?
Approx EU27 billion in Europe
What was the ORIGINAL theory of pathophysiology of migraines?
Vasodilation of cranial blood vessels generates pain
What is the neurogenic hypothesis of migraines?
Neural events increase noxious sensory transmission through trigeminal system, causing pain directly and through neurogenic inflammation
What is the brain theory of migraines?
Linked to CSD, more likely to occur in migraine with aura, but not without
What is CSD?
Cortical spreading depression
What is CGRP?
Calcitonin gene related peptide
What is neurogenic inflammation?
Activation of trigeminal sensory axons causes release of vasodilatory substances such as CGRP; mast cells activate and release more; blood vessels thus leak fluid; afferents are sensitised thus become hypersensitive to physiological stimuli
Where to ergot alkaloids occur naturally?
In fungi that infect rye
What is the ergot alkaloid MOA?
Act mainly on ADR, 5-HT or dopamine receptors
What two ergot alkaloids are related to migraine therapy?
Ergotamine and methysergide
What type of drug is ergotamine?
Ergot alkaloid
What type of drug is methysergide?
Ergot alkaloid
What is ergotamine used to treat?
Migraine
What is methysergide used to treat?
Migraine
What limits the use of methysergide?
Adverse effects
What is the MOA of ergotamine?
Acts as antagonist and partial agonist at 5-HT-1 receptors, and partial agonist at alpha-ADR
What does ergotamine cause?
Vasoconstriction and uterine contraction
What are the side effects of ergotamine?
Emesis, vasospasm and adverse affects during pregnancy
What physiological effects implicate 5-HT in the pathogenesis of migraines?
Elevated with vasoconstriction, decreased with vasodilation, increased excretion of 5-HT metabolites during migraine, decreased blood levels
What pharmacological effects implicate 5-HT in the pathogenesis of migraines?
Many drugs that are effective against migraines target 5-HT receptor signalling pathways
What are the three 5-HT1 receptors associated with migraines?
5-HT1-B/D/F
Where are 5-HT1-B receptors found?
CNS, vascular smooth muscle and many others
Where are 5-HT1-D receptors found?
Presynaptic location on peripheral and central trigeminal neurons
Where are 5-HT1-F receptors found?
Same as 5-HT1-D - presynaptic location on peripheral and central trigeminal neurons
What is the signalling function for all 5-HT1 receptors?
G-i/o protein - decreased cAMP - possible modulation of Ca channels
Name three triptans.
Sumatriptan, rizatriptan, zolmitriptan
What are the triptans used to treat?
Acute migraine attacks
What is the MOA for triptans?
5-HT1-B/D/F agonists
What do triptans cause?
Constrict large arteries - decreasing vasodilation and reducing sensory signalling; inhibit trigeminal nerve transmission - decreasing pain signalling and neurogenic inflammation
What type of drug is sumatriptan?
Triptan
What type of drug is rizatriptan?
Triptan
What type of drug is zolmitriptan?
Triptan
What receptor does sumatriptan bind?
5-HT1-B/D/F
What receptor does rizatriptan bind?
5-HT1-B/D/F
What receptor does zolmitriptan bind?
5-HT1-B/D/F
What are the side effects of triptans?
Coronary vasoconstriction, dysrhythmias, chest pain, neck and jaw pain, muscle pain, CNS effects - functional impairment and reduced productivity
What are triptans contra-indicated for?
Patients with symptoms of coronary heart disease
What may be an alternative approach to treating migraines, other than with triptans?
Target neuronal release of pain sensitising neuropeptides such as CGRP - target 5-HT1-F receptors expressed on the trigeminal nerve
What type of drug is lasmiditan?
Ditan
What receptor does lasmiditan bind?
5-HT1-F specifically
What are the advantages to the ditans?
No coronary side effects noted
What is the new class of drugs being tested for migraine treatments?
Ditans
How does lasmiditan act differently to sumatriptan?
Sumatriptan = vasoconstriction; lasmiditan = inhibition of neuronal activity
What is the preferred drug for migraine related prophylaxis?
Propranolol
Name four emerging migraine treatments.
CGRP receptor antagonists, onabotulinumtoxin, prostanoid receptor antagonism, 5-HT7 receptor antagonism
Name two CGRP receptor antagonists.
Olcegepant and telcagepant
What is the MOA of olcegepant?
CGRP receptor antagonist
What is the MOA of telcagepant?
CGRP receptor antagonist
What is olcegepant used to treat?
Migraine
What is telcagepant used to treat?
Migraine
What does 5-HT7 receptor antagonism do?
Prevents vasodilation in blood vessels in the trigeminal sensory areas