Adrenergic Agonists. Flashcards
What are the 3 ways that agonists are classed due to the way they act?
Direct acting agonists.
Indirect acting agonists.
Mixed action agonists.
What are direct acting agonists?
They will directly bind to alpha and beta receptors.
What are 5 examples of direct binding agonists?
Epinephrine.
Norepinephrine.
Dopamine.
Phenylephrine.
Clonidine.
What are indirect acting agonists?
Drugs that release norepinephrine from storgage vesicles in the pre-synaptic neuron.
What are 2 examples of indirect binding agonists?
Amphetamine.
Tyramine.
What is the action of mixed action agonists?
They directly stimulate adrenoceptors and release norepinephrine from storage vesicles.
What is an example of a mixed action agonist?
Ephendrine.
What is the action, route of administration and effects of methoxamine?
Action. Direct.
Route of administration. IV/IM.
Effects. Vasoconstriction + hypertension.
Will the hyypertensive effects of methoxamine last for a long time?
No.
Baroceptors detect the change in blood pressure and this leads to bradycardia.
What is the therapeutic use of methoxamine?
It used to treat hypotension during surgery.
What are the side effects of methoxamine?
Headaches.
Vomiting.
What is the therapeutic use and route of administration of metaramol?
Therapeutic use. Used to treat hypotension during spinal anaesthesia.
Route of administration. IM/IV/SC.
What effects will metaramol have on the body?
Vasoconstriction and increased blood pressure.
What is the action and therapeutic uses of phenylephrine?
Direct acting alpha-1 agonist.
Therapeutic uses. Nasal decongestant, mydriatic or vasopressor.
What are the actions of a mydriatic drug?
They dilate the muscles of the eye.
What are the actions of a vasopressor drug?
Vasoconstriction and increased blood pressure.
Why is phenylephrine used to treat flu?
As it causes vasoconstriction in the blood vessels of the nose.
What is the mode of action and therapeutic use of phenypropanolamine?
Mode of action. Direct alpha-1 adrenergic agonist.
Therapeutic use. It is used to treat urinary incontinence in dogs.
What is the mode of action and therapeutic use of oxymetazoline?
Alpha-1 and partial alpha-2 agonist.
Used as a nasal decongestant or as an eye drop.
What receptors will the drug clonidine act on?
Alpha 2 receptors in the cardiovascular centres of the CNS.
What are the 3 effects of clonidine on the body?
It suppresses outflow of the sympathetic nervous system.
It modulates the CNS perception of pain.
It induces sedation.
What is the best route of administration for clonidine?
Orally.
Why is clonidine a good drug to give animals that have renal problems?
As it does not affect the renal blood flow.
Where are alpha 2 receptors located and what happens when they are stimulated?
They are located in the pre-synaptic neuron and inhibit the release of norepinephrine into the synaptic cleft.
Clonidine is often given to treat what condition?
Hypertension as it acts on the cardiovascular centres associated with the CNS.
How does clonidine relieve hypertension?
By preventing the release of norepinephrine it means that vasoconstrictors are no longer in the system and this allows blood vessels to dilate.
What are the therapeutic uses and side effects of clonidine?
Therapeutic uses. Used to treat hypertension and increase sedation.
Side effects. Sedation, sexual dysfunction, bradycardia.
What is the mode of action and therapeutic use of apraclonidine?
Mode of action. Direct A2 agonist.
Therapeutic use. Used to treat glaucoma.
Drugs that are used to treat glaucoma will do what?
Reduce intraocular pressure.
Xylazine is used as what kind of drug in what animals?
As a sedative/muscle relaxant in large animals.
What is the mode of action, therapeutic use and side effects of xylazine?
Mode of action. Activation of A2 receptors in the locus coeruleus of the CNS.
Therapeutic use. Anaesthetic pre-medication.
Side effects. Bradycardia, myocardial depression.
What is the therapuetic use of detomadine?
It is used as a sedative for large animals.
It also has some analgesic action.
Detomadine will affect what kind of receptors?
Alpha-2 receptors.
How is detomadine adminstered?
Via IV.
Why would you combine detomadine with butophanol?
It improves analgesia and sedation.
Why would you combine detomadine with ketamine?
For general anaesthesia.
What is the mode of action and effects of medetomidine?
Mode of action. Alpha-2 receptor agonist.
Effects. It is a sedative with analgesic action.
What animals is medetmoidine administered to?
Small animals and horses.
What is the main use of medetomidine?
It is used to help horses and small animals come out of anaesthesia.
Romifidine is given to what animals?
Horses.
What are the effects of dexmedetomidine?
It helps small animals come out of anaesthesia and can be given in smaller doses than medetomidine.
What is the mode of action of methyl dopa?
It is metabolised to alpha-methyl norepinephrine in the pre-synaptic vesicles of the brain.
This binds to alpha-2 receptors and inhibits the release of norepinephrine.
It also inhibits DOPA decarboxylase and stops the formation of dopamine.
Methyldopa is used to treat what condition?
Hypertension.
What are the 4 therapeutic actions of alpha-1 agonists?
Treatment of hypotension.
Treatment of urinary incontinence.
Treatment of mydriasis via dilation of eye.
Use as a nasal decongestant.
What are the 4 therapeutic actions of alpha-2 agonists?What are the 4 therapeutic actions of alpha-1 agonists?
As an anaesthetic pre-medication.
Treatment of glaucoma.
Treatment of hypertension.
