Drugs Affecting the Autonomic Nervous System Flashcards
Sympathetic effect is the same as
Adrenergic effect or
Anticholinergic effect
Parasympathetic effect is the same as
Cholinergic effect or
Muscarinic effect
Stimulation of Alpha-2 receptors creates
creates a negative feedback loop and inhibits sympathetic outflow (aka sympatholytic).
Alpha2 Adrenergic Agonists Sympathetic effects: Dry mouth, constipation, nausea and gastric upset. Sympatholytic effects (similar to parasympathetic): Bradycardia, hypotension, and impotence.
The following drugs have sympathetic effects
Adrenergic Agonists
Anticholinergics
The following drugs have parasympathetic effects
Cholinergic Agonists
Alpha Adrenergic Antagonists
Beta Adrenergic Antagonists
Anticholinesterase (AChE) inhibitors
NE receptors (adrenergic):
Norepinephrine is the neurotransmitter at the synapse between the postganglionic sympathetic neuron and the effector tissue.
Epinephrine is released
Epinephrine is released from the adrenal medulla with sympathetic stimulation.
Norepinephrine receptors are subdivided into:
Alpha-1 (postsynaptic) Alpha-2 (presynaptic) Beta-1 Beta-2 Dopamine
Alpha-1 receptors
Alpha-1 (postsynaptic) causes vasoconstriction, mydriasis (radial muscles of eye contract), GI/bladder sphincter contraction
Alpha-2 receptors
Alpha-2 (presynaptic) negative feedback loop inhibiting subsequent release of neurotransmitter.
VASODILATION = lowers BP
Up- and down-regulation are known to occur in response to decreased or increased activation of receptors.
Alpha-2 receptors are also present at extrasynaptic sites in blood vessels and in the CNS. Stimulation of central alpha-2 receptors in the brainstem decreases sympathetic outflow. Stimulation of alpha-2 receptors in the pancreas inhibits insulin release.
Beta-1 receptors
Beta-1 (predominately cardiac) stimulation produces increase in heart rate and strength of contraction.
Some drugs seem to have a greater effect on strength of contraction than on rate.
Beta-2 receptors
Beta-2 (predominately non-cardiac) receptors are found on smooth muscle [e.g., bronchi; large blood vessels], bronchodilation, vasodilation, GI relaxation, uterine relaxation, glycogenolysis (hyperglycemia).
Beta-2 receptors also promote insulin release, and, in liver & muscle, gluconeogenesis & glycogenolysis as well as lipolysis in fat cells.
Dopamine receptors
Dopamine-1 (postsynaptic) receptor activation is responsible for vasodilation in splanchnic & renal circulations.
Dopamine-2 (presynaptic) receptors initiate a negative feedback loop.
At least five varieties of dopamine receptors are found in brain.
ACh receptors
Cholinergic receptors are designated as:
Muscarinic
Nicotinic
Muscarinic receptors
Muscarinic - found at postganglionic parasympathetic endings (heart; smooth muscle; glands).
Nicotinic receptors
Nicotinic - found in autonomic ganglia, adrenal medulla, CNS (and at neuromuscular junction in skeletal muscle – somatic nervous system as listed above).
ANS receptors
- NE receptors
2. Cholinergic receptors
Postganglionic neurotransmitter sympathetic effect
NE released
Postganglionic neurotransmitter parasympathetic effect
Ach released
Name(s) for agonists
-mimetic
Name(s) for antagonists
-lytic
Inhibitor
Blocker
Adrenergic drugs
Adrenergic agonist Sympathomimetic Catecholamines Alpha (-1 or -2) adrenergic, beta (-1 or -2) adrenergic "-ine"
Adrenergic-blocking drugs
Alpha-antagonist Alpha-adrenergic antagonist Sympatholytic Anti-adrenergic Alpha (-1 or -2) blockers, beta (-1 or -2) blockers
Cholinergic drugs
Muscarinic agonist
Parasympathomimetic
Cholinomimetic
Cholinergic-blocking drugs
Cholinergic antagonist
Anticholinergic
Antimuscarinic
Parasympatholytic
Uses of Adrenergic Drugs
Eye: Mydriasis (dilate eyes for eye exam)
Resp: Cause bronchodilation and manage anaphylactic shock
CV: Improve myocardial contractility, increase in heart rate and blood pressure
GI/GU: Decrease peristalsis
Endocrine: Increases blood sugar
Prolong local anesthetics