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
What are the types of alpha adrenergic agonists?
Alpha 1 selective
Alpha 2 selective
What is phenylephrine selective for?
Alpha 1
What is phenylephrine?
-causes vasoconstriction:alpha 1 effect
What are the uses of phenylephrine?
- mydriatic
- nasal decongestant: given orally or topically
What is clonidine selective for?
Alpha 2
What is clonidibe?
Partial alpha 2 agonist
Central acting anti hypertensive
Activates ventral presynaptic alpha 2 adrenoreceptors
-reduces sympathetic outflow. This reduces blood pressure
What are the examples of indirect acting adrenergic agonists?
Releasing agents
- amphetamine
- tyramine
Uptake inhibitirs
-cocaine
What are the releasing agents? What do they do?
Amphetamine
Tyramine
Cause norepinephrine release from presynaotic terminals
-Potentiate effects of norepinephrine produced endogenously
What is amphetamine?
Has central stimulation action
Can increase blood pressure by a-agonist action on vasculatyre as well as B-stimulators effects on heart
What are the uses if amphetamine?
- ADHD
- narcolepsy
What is tyramine?
Found in fermented foods such as ripe cheese and Chianti wine
- Normally oxidized by MAO
- If the patient is taking MAO inhibitirs, it can precipitate serious vasopressin episodes
- MAO inhibitors are used as antidepressants
What does cocaine do?
An uptake inhibitor
- blocks monoamine reuptake
- Moniamines accumulate in synaptic space
- This results in potentiation and prolongation of their central and peripheral actions
What are the mixed acting adrenergic agonists ?
-Ephedrine
- Pseudoehpedrine
- Induce release of norepinephrine
- Activate adrenergic receptors
What is ephedrine?
-Not a Catecholamine—> poor substrate fir COMT and MAO —> long duration
Penetrates CNS
What is ephedrine 7sed for?
Used as a receptor agent, particularly during spinal anesthesia
What us pseudoephedrine?
- one of four ephedrine enantiomers
- available over the counter as a component of many decongestant mixtures
What are the types of adrenergic antagonists?
Alpha-antagonists- non selective or a1 selective
Beta antagonists- non selective or B1 selective
Partial agonists
What are alpha adrenergic blockers? What are the types?
- Sympsthetic control of the vasvulature is mainly due to a1-adrenergic receptors
- Blockade of these receptors reduces the sympathetic tone of the blood vessels and decreases PVR
Non-selective alpha blockers
Alpha 1 blockers
What are the non selective blockers?
Phenoxybenzamine
Phentolamine
What are the phenoxybenzamine?
- Irreversible antagonist at alpha1 and alpha 2 receptors.
- Unsuccessful for hypertension
What are the uses for phenixybenzamine?
Used fir ohaeochromocytoma: prior to surgical removal of tumor
What is phentolamine? What is the use?
Reversible antagonist at alpha 1 and alpha 2 receptors
Uses:
- Phaeochromocytoma: control of hypertension during preoperative preparation and surgical excision
- Hypertensive crisis due to stimulant drug overdose
What is przaosin sekective fir?
Alpha 1
What is prazosin?
Selective blocker of the alpha-1 receptor
Lowers blood pressure by relaxing both arterial and venous smooth muscle
What 8s prazosin used fir?
Hypertension
-Used in treatment of hypertension
-Not DOC for hypertension
BPH
- DOC for symptom relief
- Relax smooth muscle in the bladder neck, prostate capsule and prostatic urethra improv8ng urinary flow
What are the B adrenergic blockers?
Non selective
B1 selective
Partial b agonists
What us the non-selective B-blocker?
Propranolol (the prototype
What are the effects of B blockers?
Slow heart rate and decrease myocardial contractility (B1 effect)
- Blockade of B2 receptors in the lungs can cause respiratory crisis in patients with COPD or asthma
- decreased glycogenolysis (B2 effect)
- decreased. Glucagon (B2 effect)
What are the general uses of beta blockers?
- hypertension.
- stable angina pectoris
- myocardial infarction
- atrial fibrillation
- hyperthyroidism
- Glaucomaa
- Migraine prophylaxis
- Performance anxiety (stage fright)
What us atenolol?
A B1 selective blocker
Useful in hypertensive patuents with impaired pulmonary function
-useful in diabetic hypertensive patients
What are the non-CNS adverse effects of beta blockers?
Bronchoconstruction
- Nonsekective beta blockers: potentially lethal adverse effect in asthmatics. Due to blockade of B2 receptors in the bronchi
- B1 selective drugs may be less likely to evoke bronchospasm
- However, the selectivity of B blockers for B1 receptors is modest: they should be avoided if at all possible in patients with asthma
Hypoglycemia
-non selective beta blockers may impair recovery from hypoglycemia in insulin-dependent diabetics. Due to blockade of B2 receptors in the liver.
- Also, beta blockers mask the tachycardia that is typically seen with hypoglycemia, denying the patient an important warning sign
- A B1 selective blocker is preferable
What are the adverse CNS effects of beta blockers?
- sedation
- dizziness
- lethargy
- fatigue
What is pindolol?
Patial B-agonist
May be preferred in individuals with diminished cardiac reverse or a properly to bradycardia
What are the adverse effects of muscuranic receptors?
Diahrrea, urination, salivation, sweating, miosis, bronchoconstriction, bradycardia, hypotension
What are the adverse effects if acetylcholinesterase inhibitors?
Diarrhea, urinate, salivation, miosis, brinchoconstriction, bradycardia,
Fasciculations, muscle weakness, paralysis. At high doses: hypotension
What are the adverse effects of antimuscuranic?
Hot, dry skin, xerostomia, mydriasis & cycloplegia, tachycardia, hyperthermia, urinary retention, constipation, confusion, delirium
What are the adverse effects of amphetamine, cocaine, ephedrine(a+ B adrenergic)
Hypertension, tachycardia, agitation, mydriasis, duaaphoresis
What are the direct acting adrenergic agonists?
Endogenous Catecholamines
Epinephrine
Norepinephrine
Dopamine
B-agonists
Isoproterenol
B1 agonists
Dobutamine
B2 agonists
Albuterol
a1 agonists
Phenylephrine
a2 agonists
Clonidine
Wear are the indirect adrenergic agonists ?
Amphetamine
Tyramine
Cocaine
What are the mixed acting adrenergic agonists ?
Ephedrine
Pseudoephedrine.
What are the adrenergic antagonists?
Alpha-antagonists
Phenoxybenzamine
Phentolamine
Alpha 1 antagonists
Prazosin
B-antagonists
propranolol
B1 antagonists
Atenolol
Partial agonists
Pindolol
