Mechanisms of Action
How does epinephrine increase heart rate?
By stimulating beta-1 adrenergic receptors in the heart.
Which receptor type does isoproterenol stimulate most?
Beta-1 and Beta-2 receptors.
What drug is used to treat anaphylactic shock?
Epinephrine
What is the common side effect of phenylephrine when used as a decongestant?
Rebound congestion
Which adrenergic receptor does phenylephrine primarily target?
Alpha-1 receptor
Name the receptor type responsible for vasoconstriction caused by phenylephrine.
Alpha-1 receptor
Which drug is commonly used as a decongestant?
Phenylephrine
Which drug can cause tachycardia and arrhythmias due to beta-1 activation?
Isoproterenol
What is the effect of isoproterenol on smooth muscle in the airways?
Relaxes airway smooth muscle by stimulating beta-2 receptors
Why is epinephrine used during anaphylaxis? (Explain its action on two systems).
Bronchodilation (respiratory system) and vasoconstriction (cardiovascular system)
Which drug is used to manage septic shock by increasing blood pressure?
Norepinephrine
What is a serious side effect of norepinephrine if extravasation occurs?
Tissue necrosis.
A patient with asthma and cardiovascular disease receives epinephrine. Why might this require caution?
Because of its potential to increase heart workload and blood pressure, exacerbating cardiovascular conditions
Compare the effects of norepinephrine on the heart and blood vessels. How does norepinephrine increase blood pressure without directly increasing heart rate?
Because of its vasoconstrictive effect that increases blood pressure. While norepinephrine does stimulate beta-1 receptors, reflex bradycardia can offset the increase in heart rate.
What is the primary clinical use of isoproterenol in heart block?
To increase heart rate and improve conduction.
Phenylephrine would be a poor choice for a patient with heart failure for this reason.
Lack of beta activity and potential to increase afterload
How does norepinephrine differ from epinephrine in terms of receptor activation?
Norepinephrine has little beta-2 activity compared to epinephrine
Which drug primarily works on beta receptors with little to no alpha activity?
Isoproterenol
Isoproterenol can help in bradycardia but is avoided in patients with this cardiac issue.
Ischemic heart disease due to its ability to worsen tachycardia and oxygen demand
What adverse effect can occur when using norepinephrine without adequate fluid resuscitation?
Ischemia due to excessive vasoconstriction