Adrenergic Agonists and Antagonists Flashcards
What are drugs that mimic epinephrine or norepinephrine called?
Sympathomimetic drugs
What are the two types of sympathomimetics?
Direct-acting – Directly activate adrenoceptors.
Indirect-acting – Enhance endogenous catecholamine activity
What are the main functions of α1 receptors?
Vasoconstriction, pupillary dilation, hair erection, prostate contraction, increased heart contractility
What are the main functions of α2 receptors?
CNS modulation, platelet aggregation, inhibition of neurotransmitter release, vasoconstriction, inhibition of lipolysis
What are the main functions of β1 receptors?
Increased heart contractility, HR, and renin release
What are the main functions of β2 receptors?
Smooth muscle relaxation (lungs, uterus, vessels), potassium uptake, glycogenolysis
What are the main functions of β3 receptors?
Bladder relaxation, fat cell lipolysis
What are the functions of D1 receptors?
Modulate neurotransmitter releaseDilate renal blood vessels
What happens when α1 receptors are activated?
Vasoconstriction, increased BP
What happens when α2 receptors are activated?
Local administration → Vasoconstriction.
Systemic administration → ↓ Sympathetic tone, ↓ BP
What is an example of an α1 agonist?
Phenylephrine
What happens when β1 and β2 receptors are activated?
Increased cardiac output, HR, contractility (β1), and vasodilation (β2)
What drug activates both β1 and β2 receptors?
Isoproterenol
What is the net effect of β receptor activation on BP?
↑ Systolic BP, ↓ Diastolic BP, ↓ Mean Arterial Pressure (MAP)
Q: What effects does dopamine have on the cardiovascular system?
Low doses → β1 activation → ↑ Heart rate & contractility.
High doses → α1 activation → Vasoconstriction.
D1 activation → Renal & splanchnic vasodilation
What effect does β2 receptor activation have on the lungs?
Bronchodilation
What type of drugs are used in asthma treatment?
β2 agonists
What happens when α1 receptors in the pupillary dilator muscle are activated?
Mydriasis (pupil dilation)
How do β antagonists help treat glaucoma?
They reduce aqueous humor production
How do α1A receptors affect the bladder and prostate?
Contraction → Urinary continence
What drug class is used to treat urinary obstruction in BPH?
α1A antagonists (e.g., tamsulosin)
What effect do sympathomimetics have on salivary glands?
Can cause dry mouth (↓ secretion of amylase & water)
How do amphetamines affect the CNS?
Improve attention, elevate mood, can cause psychosis (dopamine receptor activation)
Do catecholamines cross the blood-brain barrier?
No, but they can still cause nervousness & tremor
