Aadrenergic Drugs Flashcards
What diseases can often be treated by adrenergic drugs?
- hypertension
- Anginaa
- Heart failures
- Arryhthmias
- Asthma
- Migrainne
- anaphylactic reactions
What dies the exact adrenergic response Demond on?
Depends on the portion of alpha and beta receptor in tissue
Norepinephr8ne has little effect in B2 receptors, theref8re it cannot cause bronchodilation, beca7se receptors in bronchial smooth muscle are B2
In contrast epineohrineis a potent bronchodilator
Why can norepinephrine and epinephrine cause constriction in skin blood vessels?
Skin blood vessels express almost exclusively a1 receptors; thus norepinephrine and epinephrine cause construction
What are the adrenergic responses to blood vessels in smooth muscle?
The smooth muscle blood vessels”s in skeketal muscles gas both B2 and a1 receptors
Activation of B2 receptors causes vasodilation
Activation of a1 causes vasoconstriction
Contrast the adrenergic response of B2 receptors and a1 receptors
B2 receptors are more sensitive to epinephrine than a1 receptors : low concentrations of epinephrine cause vasodilation
Physiological concentrations of epinephrine cause primaarily vasodilation in such vessels
But at high concentrations of epinephrine, both a1 and B2 receptors are activated, and the response to a1 receptors predominates, therefore vasoconstriction results
What dies the response of a target organ ti sympathomimetic organs dictated by?
The direct effects of the agents and reflex homeostatic responses of the organism
What are the types of direct acting adrenergic agonists ?
Endogenous Catecholamines
B-adrenergic agonists
Alpha-adrenergic agonists
What are the types of indirect acting adrenergic agonists?
Releasing agonists
Uptake inhibitors
What are the endogenous Catecholamines?
- epinephrine
- norepinephrine
- dopamine
Explain the Catecholamines structure
Norepinephrine, epinephrine and dopamine- have -OH groups substituted at positions 3 and 4 of the benzene ring
Since o-dihydroxybenze ring is also known as Catechol, sympathomimetic amines with these hydroxyl substitutions in the aromatic ring are called Catecholamines
What is epinephrine ?
Acts as a hormone: released from adrenal medulla, acts on distant cells
- epinephrine is an agonist at both a and B adrenoreceptors
- At low concentrations epinephrine activates mainly B1 and B2 receptors
- At higher concentrations a1 effects become more pronounced
What are the general effects if epinephrine?
- Increases heart rate and contractile (B1 effect)
- Cardiac output increases: oxygen demand fir the myocardium increases
- Increases renin release (B1 effect)
- Cinstructs arterioles in skin and vuscera(a1 effect)
- Dilates blood vessels of skeletal muscle (B2 effect)
- Relaxes bronchial smooth muscle (B2 effect)
- increases liver glycogenolysis (B2 effect)
- Increases lipolyisis (B1 and B2 effect)
What are the eff3crs of epinephrine on blood pressure when given on IV?
There is increase in blood pressure due to:
- Ventricular contraction (B1 effect)
- Increased heart rate( B1 eff3ct) this may be opposed by the baroreceptor reflex
- Vasoconstriction (a1 effect)
What are the effects on blood pressure in epinephrine with low doses of IV?
- peripheral resistance decreases, because B2 receptors are more sensitive to epinephrine than a1 receptors. Diastolic pressure falls
- Systolic presssure increases due to increased cardiac contractile force (B1 effect)
- heart rate increases (B1 effect)
- there is No increase in mean blood pressure, so the baroreceptor reflex doesn’t kick in- the eff3cts of epinephrine depend on the dose and the ratio of the a1 to B2 responses
What are the uses of epinephrine?
- Anaphylaxtic shock : drug of choice
- cardiac arrest
- acutevasthmatic attacks
What receptors respond to norepinephrine?
- agonist at a1, a2, and B1 receptors
- little action on B2 receptors
What are the effects if the norepinephrine?
- Causes peripheral vasoconstriction (a1 effect)
- Increases cardiac contractility (B1 effect)
- Systemic administration of norepinephrine increases peripheral vascular resistance, systolic blood pressure and diastolic blood pressure
- The increase in blood pressure stimulates baroreceptors leading to reflex bradycardia
What are the uses of norepinephrine?
To treat shock because it increases vascular resistance and therefore increases blood pressure
What are the B-adrenergic agonists?
- Non-sekective(B1 & B2)
- B1 selective
- B2 selective
What is isoproterenol? What is it used to do?
Non-selective B agonist
Used to:
In emergencies to stimulate heart rate in patients with Bradycardia or heart attack
Explain isoproterenol as a non-selective B-adrenergic
- activates B1 and B2 adrenergic receptors
- Increases heart rate, force of contraction, and cardiac output(B1 effect)
- Dilates arterioles of skeketal muscle (B2 effect), resulting in a decrease in peripheral vascular resistance
- Diastolic pressure falls. Systolic blood pressure may remain unchanged or rise
- Mean arterial pressure typically falls
- Causes bronchodilation (B2 effect)
What is dobutamine selective for?
B1
What is dobutamine?
Predominantly B1 agonis. Given IV
Potent inotropic, with cooperatively mild chronotropic effects
- Produces less increase in HR and less decrease in PVR than isoproterenol
- causes mild depression
- increases myocardial O2 consumption. This is the basis of the dobutamine stress echocardiogram
What are the uses of dobutamine?
- management of Acute heart failure.
- Management if cardiogenic shock
What is albuterol sekective fir?
B2
What is albuterol?
- causes bronchodilation (B2 effect)
- used in asthma
- DOC fir acute asthma attacks