32 - Drugs Affecting Nervous System Flashcards
(41 cards)
Exception to the rule that sympathetic nervous system releases noradrenaline to target
Sweat glands, where sympathetic nervous system releases ACh onto muscarinic AChR
Botulinumtoxin function
Stops membrane fusion between ACh vesicles and synaptic membrane by degrading SNARE proteins on vesicle.
Effect of botulism
Flaccid paralysis
What is targeted by botulinumtoxin?
Has selectivity for uptake into cholinergic neurons. Mechanism not known.
Conditions that are treatable with botulinumtoxin
1)
2)
1) Blepharospasm - Overactive blink response, makes someone functionally blind. Botox relaxes muscles involved in blinking.
2) Excessive underarm sweating - Botox inhibits ACh function of muscarinic receptors in sweat glands
Selectivities of anticholinesterase drugs
Selective between NMJ and postganglionic parasympathetic juncitons
Examples of anticholinesterase drugs
1)
2)
3)
1) Edrophonium
2) Neostigmine/pyridostigmine
3) Donepezil
Edrophonium
Anticholinesterase drug
Short duration
Used to diagnose myasthenia gravis
Neostigmine/pyridostigmine
Medium-duration anticholinesterase drug
Used to treat symptoms of myasthenia gravis
Used to reverse effect of non-depolarising neuromuscular blockers
Donepazil
Anticholinesterase
Enters CNS, used to treat symptom of Alzheimer’s (reduction in ACh signalling in CNS)
Myasthenia gravis
Autoimmune disease, where antibodies are made against nicotinic receptors on skeletal muscle motor endplates.
Leads to blockage, C’ disruption of post-synaptic membrane –> Loss, internalisation of nicotinic receptors
What can be used to treat myasthenia gravis symptoms?
Anticholinesterse drugs.
Reduces degradation of ACh on motor endplate.
This isn’t a cure, as the number of functional nicotinic receptors decreases with time, so eventually anticholinesterase drugs won’t have an effect.
Can also use immunosuppressants to slow release of anti-nicotinic Ig
Test for myasthenia gravis
Tensilon test
Tensilon test
Diagnostic test for myasthenia gravis Administer edrophonium (trade name Tensilon), see if motor weakness lessens
Type of ACh receptors in autonomic ganglia
Nicotinic N (Nn) ACh receptors
Use of autonomic nicotinic ACh agonists
Smoking cessation
Use nicotine patches, varenicline
Clinical uses of somatic nicotinic ACh antagonists
Pre-surgical muscle relaxation (EG: non-depolarising: tubocurarine, vecuronium)
Example of a ganglionic nicotinic ACh antagonist
Hexamethonium
Autonomic muscarinic agonism effects 1) 2) 3) 4) 5)
1) SLUD - salivation, lacrimation, urination, defecation
2) Sweating
3) Bronchoconstriction
4) Bradycardia
5) Vasodilatation (non-neural effect)
Example of a therapeutic autonomic muscarinic agonist
Pilocarpine, for treating glaucoma
Autonomic muscarinic antagonism effects 1) 2) 3) 4)
1) Decreased salivation, lacrimation, urination, defecation
2) Reduced sweating
3) Tachycardia
4) Bronchodilation
Examples of anti-muscarinic drugs
1)
2)
3)
1) Atropine
2) Hyoscene
3) Ipratropium
Atropine 1) 2) 3) 4) 5) 6)
1) Anti-muscarinic
2) Reduces secretions (for surgery)
3) Bronchodilation
4) Bradycardia
5) Pupil dilation (for examining eye)
6) Treating AChE-inhibitor poisoning (EG: with organophosphates)
Hyoscene
Anti-muscarinic
For motion sickness
