2nd lecture - sympatholytics

Question 1

The peripheral nervous system is divided into three sub-systems:

Answer 1

The sensory system
The somatic motor system
The autonomic system

Question 2

The autonomic system controls

Answer 2

the glands, heart and smooth muscles

Question 3

The autonomic system is divided into

Answer 3

Sympathetic system – activated during critical situations

Parasympathetic system – active at rest

Question 4

adrenoblockers can also be called (2)

Answer 4

sympatholytics
or
Adrenergic receptor antagonists

Question 5

what do Adrenergic receptor antagonists do

Answer 5

Interact with adrenergic receptors and by occupying these sites do not allow an adrenergic agonist access to the receptor.

they block stimulus or action from occuring via the receptors they block

Question 6

alfa 1 blockade removes the pressor response to what substance?

Answer 6

norepinephrine

alfa blockade not only prevents the pressor response to epinephrine, it converts it to a depressor response (epinephrine reversal).

Question 7

What type of agonist is epinephrine?

Answer 7

mixed alfa-beta agonist

Question 8

When alfa-1 receptors are occupied by a blocker, only the vasodilator beta-2 receptors are available for interaction with epinephrine which means that epinephrine causes

Answer 8

a fall in blood pressure.

Question 9

if alfa1 receptors of blood vessels are occupied by alfa
1 blocking agents, they are no longer available to

Answer 9

mimetics.

Question 10

an example of a natural alfa-adrenoblocker

Answer 10

ergot alkaloids (dihydroergotamine)

Question 11

examples of synthetic alfa-adrenoblockers (3)

Answer 11

Phentolamine (α1 and α2, used rarely in vet)

Yohimbine, atipamezole, tolazoline (α2 selective)

Prazosin/pratsiol (α1 mainly)

Question 12

ergot alkaloids are

Answer 12

fungal toxins found in grains

they are a natural alfa adrenoblocker

Question 13

severe ergot alkaloid poisoning can cause

Answer 13

strong hypotension, gangrenous necrosis of tissues.

Chronic poisoning - ergotism. Weakness, nausea, headache, vasoconstriction and finally gangrene.

Question 14

cardiovascular effects of ergot alkaloids

Answer 14

intense spasm of peripheral blood vessels, caused by direct-acting effect on the smooth muscle of the blood vessels.

Higher doses cause hypotension and central blood vessels to dilate (beta2 receptor dominance in the presence of α1 blockade). The heart rate and the tone of smooth muscle organs will increase.

Larger doses block the α1 receptors, α1 receptor-mediated effects of agonists are inhibited. beta receptors are not affected.

Question 15

clinical use of ergot alkaloids

Answer 15

postpartum uterine contraction strengthening (rarely)

in humans, as a migraine treatment

Question 16

Synthetic α blocking agents do what

Answer 16

They alter pressor effects of catecholamines (can cause epinephrine reversal), but the total cardiovascular effects are from a variety of factors such as concomitant antihistaminic, antiserotonergic and anticholinergic effects.

Question 17

prazosin/pratsiol blocks which receptors

Answer 17

alfa 1

α1 adrenoblockers cause blood pressure to drop. This is attributable to the drugs blocking the effect of sympathetic impulses on the smooth muscle of the blood vessels.

At the same time, the effect of β2-receptors that decreases the tone of blood vessels has been maintained – causing blood pressure to decrease even further.

Question 18

atipamezole/antisedan/sedastop blocks what receptors?

Answer 18

alfa 2

Question 19

Phentolamine interacts with what receptors?

Answer 19

Phentolamine interacts with α1 and α2 receptors as an antagonist.

It causes a decrease in blood pressure, blood vessels dilate, uterus relaxes.

Question 20

Prazosin/pratsiol interacts with what receptors?

Answer 20

Selective α1 blocker.

It is used for eliminating peripheral spasms and for decreasing blood pressure.

Question 21

active ingredient of cardisure and vetmedin

Answer 21

pimobendan, a non-glycoside inotrope

Question 22

what type of drug is atipamezole

Answer 22

Selective α2 blocker

causes a dilation of blood vessels, increased uterine muscle tone and the dilation of blood vessels in the skin and mucous membranes.

is the reversal agent for common alfa 2 adrenomimetics such as dexmedetomidine

Question 23

Dexmedetomidine favors what receptors?

Answer 23

is a highly selective α-2 agonist

Question 24

what type of drug is Mirtazapine

Answer 24

α2-blocker

has antihistamine and antiserotonergic activity.

used as an appetite stimualnt in cats, antidepressant in humans.

Question 25

the first β-blocker that was discovered (1958)

Answer 25

Dichloroisoproterenol

It is non-selective for the β₁-adrenergic and β₂-adrenergic receptors.

parent substance to the development of successful beta blocker propranolol

Question 26

Pharmacokinetics of α blockers

Answer 26

Local irritating properties – clinical use PO or IV.

Biotransformation pathways not clarified.

Several of these drugs may localize in body adipose tissue because of their relatively high fat solubility.

Question 27

Mechanism of action of beta-adrenoblockers

Answer 27

direct selective blocking of β receptors, the β effects from sympathetic innervation of organs will cease.

Question 28

Mixed β blockers inhibit the relaxation of

Answer 28

bronchial muscles and cause constriction. This is particularly dangerous in case of asthmatic conditions.

Question 29

general Clinical use of β blockers (5)

Answer 29

arrythmias
hypertension
ischemic heart disease
myocardial infarction
migraines

Question 30

Usage of β1 blockers in veterinary medicine

Answer 30

The primary usage occurs in small animal clinics.

They are used in the case of weakened heart muscle and chronic heart failure.

Can also be used in digitalis overdose cases.

Question 31

Reserpine inhibits

Answer 31

“noradrenaline uptake inhibitor”

the uptake of the mediator noradrenaline into storage vesicles. The noradrenaline synthesized from dopamine will remain available and will be broken down by MAO. The deposits will empty.

Exogenously administered catecholamines act on the background of reserpine.

Arterial pressure decreases and pressure increasing effector mechanisms are depressed. This leads to a sedative effect and depression.

Question 32

Guanethidine is mainly used

Answer 32

in human medicine for the treatment of hypertension.

causes noradrenaline depot paralysis.

Question 33

Methyldopa prevents

Answer 33

the conversion of DOPA into dopamine and noradrenaline. It inhibits the synthesis of noradrenaline.