neuromuscular pharmacology Flashcards
what is pharmacology
how drugs interact with living organisms to produce a change in function
what is pharmacodynamics
what the drug does to the body
- what does it target
- what is the response
what is parmacokinetics
what the body does to the drug
- movement of the drug within the body
- where does the drug go
- therapeutic plasma concentration (concentration in blood effective but not toxic)
what is pharmacy
storing, prescribing and dispensing drugs
what are the different considerations when selecting, prescribing, and dispensing different drugs
- correct indication with no contraindications
- efficacy
- route of administration
- legalisation
- pathophysiological status of the animal (young, old, pregnant, other disorders)
- short (acute) vs. long term (chronic) therapy
- cost
- owner education
- farm animal (meat/milk withdrawal, individual vs. group therapy)
what is efficacy
the effectiveness of the drug to treat the condition
- evidence based
- underlying science is important
- NOT the same as potency (how strong the drug is)
what is the regulatory body for veterinary medicines
Veterinary Medicines Directorate
what is absorption and reuptale of drugs influenced by
- route of administration
- physiochemical properties of the drug
- status of gastro-intestinal tract (acidity of stomach, motility)
- taken with food
- formulation (fast acting vs. slow release
how are drugs distributed
- transported in the plasma
- most drugs temporarily bind to a plasma protein
- will unbind (become active) and leave the blood to target different body fluids
- different drugs will distribute to a lesser or greater extent
what are the 4 main targets that the drug interacts with to exert its effects within the body
- receptors
- ion channels
- enzymes
- carrier
what is an agonist
drugs that bind receptor and activate them (sgtimulate a particular function)
what is an antagonist
drugs that bond receptors but do not activate them (block the effects of agonsists)
what is an example of a drug that acts on an ion channel
lidocaine
- blocks sodium channels to prevent depolarisation and firing of the nerve synapse
how do drugs interact with enzymes
typically, a drug is an enzyme inhibitor and thus decrease their activity
- penicillin blocks cell wall synthesis in E. Coli
most drugs target enzymes
how are drugs eliminated by metabolism
- can be metabolised by liver and inactivated
- drug metabolite (metabolised product) often excreted by the kidney
- the goal of metabolism is to make the drug more easily soluble by water (make it more polar and hydrophilic) so that it can be excreted by the kidney
- some drugs are directly excreted by through the urine by the kidney (often polar)
- renal diseases can impact the ability to excrete drugs properly, leading to a build up in the body
what are the events, in chronological order, that a drug will take through the body
- absorption
- distribution
- metabolism
- excretion
what are the unwanted side effects of a drug
- adverse events (predicted vs idiopathic (not predicted))
- drug has no effect (not even intended effect)
true or false: a free, unbound drug is active
True
do most drugs bind temporarily to albumin?
yes
rank the following mechanisms from fastest to slowest
- secondary messengers
- nuclear receptors
- ligand gated ion channels
- ligand gated ion channels
- secondary messengers
- nuclear receptors
The Veterinary Medicine Directorate (VMD) runs a scheme to monitor unwanted effects of drugs - what ois it called
SARSS
The VMD scheme to report adverse medicines includes what groups
- animals
- humans
name the main components of the autonomic nervous system
- the sympathetic system
- the parasympathetic system
- the enteric system
what is a precursor for acetylcholine
choline
what are the 2 receptors that acetylcholine binds to
- muscarinic
- nicotinic
what effects would IV atropine have on a cat?
- tachycardia (increased HR)
- Dries secretions
- pupil dilation
what is an example of a nicotinic agonist that is used therapeutically
suxamethonium
how does botulinum toxin work
binds pre-synaptically to prevent acetylcholine release
what is the precursor of noradrenaline
tyrosine
which enzymes degrade noradrenaline
- monoamine oxidase
- catechol-O-methyltranferase
dexmedetomdine is commonly used sedative and alagesic drugs used in dogs and cats. which receptors does it target
presynaptic alpha 2 receptors
anitpamezole is an alpha 2 receptor antagonist. what will happen if you give it after an alpha 2 agonist
antagonism of the agonist
which types of drugs improve cognitive function in elderly dogs
mono amine oxidase inhibitors
what is the effect of activation of an alpha 1 receptor
vasoconstriction
what are neurotransmitters and what are the major ones of interest
a chemical substance which is release at the end of a nerve fibre by the arrival of a nerve impulse and by diffusing across the synapse or junction which effects the transfer of the impulse to another fibre
- acetylcholine
- dopamine
- GABA
- glutamate
- noradrenaline
- histamine
- etc…
what is the stepwise process involved in synthesis, storage and release of amine and amino acid transmitters
- uptake of precursors
- synthesis of transmitter
- uptake/transport of transmitter into vesicles
- degradation of surplus transmitter
- depolarisation by propagated action potential
- influx of calcium ions in response to depolarisation
- release of transmitter by exocytosis
- diffusion to postsynaptic membrane
- interaction with postsynpatic receptors
- inactivation of transmitter
- reuptake of transmitter or degradation products by nerve terminals
- uptake and release of transmitter by non-neuronal cells
- interaction with presynaptic receptors
what type of transmitters fo cholinergic nerves have
acetylcholine transmitters
what are the 2 receptors that noradrenaline bind to
- alpha
- beta
give an example of a muscarinic agonist and what is it used for
pilocarpine: used in neurogenic “dry eye” to stimulate tear production
give an example of a muscarinic antagonist and what is it used for
atropine: used to speed up heart rate and dry secretions (when there is too much)
or
scopolamine: used for abdominal pain
give an example of a nicotinic agonist and what is it used for
suxamethonium: overstimulates neuromuscular junction to stop muscles from spasm
give an example of a nicotinic antagonist and what is it used for
alpha bungarotoxin/vecronium: neuromuscular blocking agent
what drugs inhibit acetylcholineesterase
carbamate insecticides, organophosphates, neostigmine
what is the pathway of noradrenaline
- produced from tyrosine (tryosine enters cell, tyrosine hydroxylase turns it into dihydroxyphenylalanine, which turns into dopamine via decaboxylation, dopamine beta hydroxylase turns dopamine into noradrenaline)
- action potential causes vesicle to bind to membrane and release noradrenaline into synaptic cleft
- noradrenaline binds to either pre or post synaptic adrenoreceptors OR action is terminated by monoamine oxidase (MAO) and reuptake
give an example of an alpha 1 agonist and what is it used for
adrenaline: for cardiac arrest
give an example of an alpha 2 agonist and what is it used for
medetomidine/romifidine/xylazine for sedation/analgesia
give an example of a beta 1 agonist and what is it used for
Dobutamine: increasing blood pressure
give an exmaple of a beta 2 agonist and what is it used for
salbutamol: for asthma (causes bronchodilation)
give an example of an alpha 2 antagonist and what is it used for
antipamezole: reversal of sedation/analgesia
give an example of a beta antagonsit (beta blocker) and what is it used for
propranolol: slows down HR
in terms of noradrenaline receptors, what do each of them act on generakly
alpha 1 receptor: blood vessels (vasoconstriction)
alpha 2 receptor: blood vessels, nerve terminals (autoreceptors) - inhibition of transmitter release
beta 1 receptor: heart (tachycardia), increased force
beta 2 receptors: blood vessels (vasodilation), bronchi (bronchodilator), liver (glycogenolysis)
what drugs influence MOA inhibitors and increase noradrenaline availibility
MOA-A inhibitors not used in animals
MOA-B inhiibitors: treat canine cognitive dysfunction by increasing dopamine
what drugs affect the synthesis or stimulating synthesis of noradrenaline and what are they used for
carbidopa/levodopa used for Parkinsons disease
what drugs affect re-uptake and what do they get used for
- tricyclic antidepressants used as analgesics for chronic pain
- fluoxetine, clomipramine for behavioural issues
