adrenergic drugs Flashcards
What is the dominant system involved in the rapid regulation of blood pressure?
SNS
SNS stands for the Sympathetic Nervous System.
What is the formula for blood pressure (BP)?
BP = CO x PVR
CO is cardiac output and PVR is peripheral vascular resistance.
What are sympathomimetics?
Drugs that mimic the action of NE/epinephrine (adrenergic drugs)
NE stands for norepinephrine.
What are the two types of adrenergic drugs?
- Direct acting
- Indirect acting
What do direct adrenergic agonists do?
Activate receptors directly
This can involve one or more subtypes depending on the drug.
What is the effect of the presence of –OH groups in sympathomimetic drugs?
- Indicates catecholamines
- The absence of one or both –OH groups decreases potency at adrenergic receptors and suseptibility to COMP (metabolism).
What do indirect adrenergic agonists do?
Increase the amount of NE at the synapse
This involves multiple subtypes given non-specificity
What is the effect of the presence of group addition to the a-carbon in sympathomimetic drugs?
creates resistance to MAO (metabolism)
What is the role of alpha-1 adrenergic receptors?
- Vasoconstriction in blood vessels of organs and skin
- Dialation of pupil and decreasing aqueous humour
(increases blood pressure and redirects blood flow to vital organs)
What is the effect of beta-2 adrenergic receptors on blood vessels?
Vasodilation in skeletal muscles
Beta-2 receptors are primarily responsible for this effect.
What happens to blood pressure when it decreases?
Baroreceptors initiate reflex pathways to regulate BP
(Ex. BP too low, baroreceptors detect – decr. PSNS and incr. SNS)
This involves SNS and PSNS activity.
What is the function of clonidine?
α2 agonist used to treat hypertension
It reduces BP by acting in the CNS.
What are indirect acting sympathomimetics?
- Tyramine
- Amphetamine
- Cocaine
What can excessive use of sympathomimetics lead to?
- Cardiovascular toxicities like tachycardia and arrhythmias (done via B1 agonists, nonselective moreso than selective)
- Restlessness and Hyperactivity in CNS (via indirect agonists)
direct agonists don’t induce toxicity in CNS.
Particularly at risk are the elderly and those with prior heart issues.
What is the mechanism of action of adrenergic antagonists?
Block α or B receptors activated by NE or epinephrine
This leads to effects similar to PSNS activation.
What is the effect of beta-1 antagonists on the heart?
Decrease heart rate and force of contraction
Fill in the blank: Adrenergic antagonists have the same effect as _____ activation.
PSNS
What receptors do beta-blockers primarily inhibit?
β1
This leads to decreased cardiac output.
What receptors do alpha-blockers primarily inhibit?
a1
This leads to vasodilation
What is the effect of alpha-1 antagonists on blood vessels?
Vasodilation in organs and skin
What is a common use for phenylephrine?
Used in nasal sprays to relieve congestion
True or False: Direct agonists of adrenergic drugs are rarely associated with toxicity in CNS.
True
What is the primary effect of beta-2 agonists in the bronchi?
Bronchodilation
What type of adrenergic antagonist acts on smooth muscle walls of organs?
β2 antagonist
These antagonists block β2 receptors, leading to various physiological effects.
What effect does blocking α1 receptors have on sphincter smooth muscle?
Relaxes sphincter
Blocking α1 receptors leads to relaxation of sphincter smooth muscle.
What happens when β2 receptors are blocked in the bronchi?
Bronchoconstriction
Blocking β2 receptors in the bronchi causes bronchoconstriction.
What impact does blocking β2 receptors have on the gastrointestinal tract?
Increases motility
Blocking β2 receptors leads to increased gastrointestinal motility.
Fill in the blank: Blocking α2 receptors ____ ACh release, leading to increased motility.
Increases
Blocking α2 receptors results in an increase in ACh release.
What is the effect of blocking β2 receptors on the urinary bladder?
Contracts bladder
Blocking β2 receptors in the urinary bladder causes contraction.
What effect does blocking α1 receptors have on the urinary bladder sphincter?
Relaxes sphincter
Blocking α1 receptors in the urinary bladder sphincter leads to relaxation.
Which adrenergic drugs could be used to treat cardiac arrest?
Epinephrine
Epinephrine is commonly used in cardiac arrest situations.
Which adrenergic drugs could be used to treat anaphylactic shock?
Epinephrine
Epinephrine is effective in treating anaphylactic shock due to its bronchodilator and cardiovascular effects.
What is Vascular Tone/Peripheral Vascular Resistance (PVR)?
- the degree of constriction or dilation of blood vessels
- primarily controlled by the smooth muscle in the vessel walls.
- It determines blood vessel diameter and regulates blood pressure and blood flow to organs.
The difference between norepinephrine and epinephrine is the presence of ____. This difference results in what difference between the two in terms of function?
- a group of the amino-terminal end (on epinephrine).
- alters affinity – the larger to compound, the more affinity it has for B-receptor activity.
epinephrine can bind B-receptors, and norepinephrine can not.
Where are a1 receptors found in the body?
- eye
- spincters (bladder, etc.)
- blood vessels (organs and skin)
Where are a2 receptors found in the body?
- GI tract
- blood vessels (organs and skin)
Where are B1 receptors found in the body?
- heart
where are B2 receptors found in the body?
- lungs
- GI tract
- bladder (smooth muscle)
- liver
How do amphetamines work?
stimulates release of NE by converting reuptake receptors on the presynaptic neuron into reversed transporters.
How does cocaine work?
Prevents reuptake of NE into the presynaptic neuron by blocking the reuptake transporter.
