Flashcards in ANS Drugs Deck (61)
Selective B1 agonist
Structurally resembles dopamine but has little activity at DA receptors.
Inotropy, chronotropy, but ino bigger because B2 dominate at SA.
Cardiac decompensation after CHF or cardiac surgery. Can cause ventricular ectopic activity.
Direct agonist at D1>B2>A
Low Dose; Renal dose activates only D1 receptors. Increase renal blood flow and urine output. Can cause hypotension
Intermediate dose: activates D1 and B1 receptors
Increased renal blood flow, heart rate, cardiac contractility, and CO. Generally no change in TPR. Can cause hypotension
High dose: activates all receptors. Causes vasoconstriction and increased BP.
Treatment of cardiogenic shock especially in oliguric patients.
Fenoldopam and use
D1 agonist. Dilates peripheral vessles and increases natriuresis. Used to treat severe hypertension and in patients with renal compromise.
When NOT to use fenoldopam?
In patients with glaucoma.
Selective B2 agonist.
Used as a bronchodilator for asthma and other pulmonary disease.
Works by increasing cAMP in bronchial smooth muscles which causes relaxation and stabilization of mast cells.
Alpha agonist, only slight affinity for a1. Causes vasoconstriction.
Can be used for hypotension, but much more commonly is used as a decongestant
Selective A2 agonist.
Decreases sympathetic outflow from the CNS.
Used in management of HTN and hypertensive crisis.
Drowsiness, fatigue, xerostomia
Not clinically used, but a byproduct of tyrosine metabolism, which is degraded by MAO-A>MAO-B
Evokes release of NE from adrenergic nerves.
Can cause hypertensive crisis.
Black Box warning for Beta blockers
Abrupt withdrawal from beta blockers can cause angina/MI due to upregulation of receptors. If taken off beta blockers too quickly, heart will be hyperactive and need lots of O2.
Who should avoid B blockers
Asthmatics (due to possibility of B2 blockade -> bronchospasm)
Also, diabetes patients. Beta blockers can induce hypoglycemia and prevent diabetics from feeling the symptoms of hypoglycemia.
Non selective B antagonist
Used for angina/svt and vt/pvc/htn/mi/pheochromocytoma
Selective B1 antagonist, but can block B2 receptors at the doses used for treating angina.
Used for stable angina/chf/hypertension
Partial agonist at B1, B2 receptors.
So this has ISA (intrinsic sympathomimetic activity). In the absence of normal agonist, it is an agonist. Acts as a beta antagonist when sympathetic drive is high.
Stimulation in a limited range.
Used for HTN and angina.
NO blackbox warning.
B1 and A1 antagonist.
Partial agonist at B2 (intrinsic sympathomimetic activity).
Used in hypertensive emergency, especially due to excessive sympathetic activity. Tyramine crisis, pheocromocytoma, methamphetamine.
Antagonist at B1 and B2 receptors. But also some A1 receptor blockade, so has vasodilatory effect.
Inhibits cardiac remodeling in CHF. Less effect on glucose metablolism than others.
Alpha antagonist with similar activity at A1 and A2.
Causes hypotension, but used to treat hypertensive emergency due to sympathetic overactivity.
Parasympathetic effects on the vasculature
Vagal activity does not affect vascular tone because they're not parasympathetically innervated. However. Muscarinic receptors on endothelium causing NO induced vasodilation.
Parasympathetic effects on heart
Isolated in atria.
How does vagal tone decrease chronotropy?
Muscarinic receptors on SA node increases current through Girk channels (hyperpolarizing). Funny current intact but more time needed to drive Vm to spike threshold.
How does vagal tone decrease lusitropy
Reduces cAMP dependent phosphorylation of L-types in AV node causing reduced Ca flow out, makes it slower.
Parasympathetic effects on the body
Bronchoconstriction, increased secretions, increased GI motility, relaxation of sphincters, contraction of bladder wall, miosis, near vision, miosis, near vision.
Full agonist at MAchR and NAChR.
Degraded very quickly by plasmacholinesterases
Muscarinic agonist. Negligible nicotinic activity.
Long duration of action.
Used for urinary retention, neurogenic bladder.
Contraindicated in asthma
Agonist at nicotinic receptors.
Activates ganglia (both parasympathetic and sympathetic outflow, so produces dominant tone).
Increases BP, Increases HR (due to epi release)
Anticholinesterases. Prevent degrading of ACh in synapse. Used in myesthenia gravis, and atropine poisoning.
Neostigmine can't cross BBB.
Anticholinesterase poisoning (organophosphates)
Sludge and the killer B's
Bronchorrhea, bronchospasm, bradycardia
Atropine and scopolamine.
Hot as a hair, mad as a hatter, dry as a bone.
Used for AV block and for bradycardias.