Autonomic Nervous System Pharmacology

Mecamylamine

Neuronal Nicotinic antagonist

Blocks Neuronal Nicotinic Receptors

used for hypertension; CNS penetration

is important to it's effects

Carbacol; Methacoline; Bethanecol

Muscarinic agonist; ACh analog

Activates Muscarinic Receptors

AChE-resistant ACh analog; retains variable

nicotinic agonist activity

Muscarine; Pilocarpine; Arecoline

Selective Muscarinic agonist

Activates Muscarinic Receptors

Alkaloids; Selective

Atropine

Muscarinic antagonist

Blocks Muscarinic Receptors

can treat/prevent effects of succinylcholine usage

Oxybutynin ;ipratropium

Muscarinic antagonist

Blocks Muscarinic Receptors

a-methyltyrosine

catecholamine Synthesis inhibitor

Inhibits tyrosine hydroxylase

Blocks Rate -Limiting step in catecholamine

synthesis

L-Dopa

Catecholamine precursor (dopamine)

Enters downstream of tyrosine hydroxylase

Bypasses tyrosine hydroxylase; Dopamine Synthesis continues; Parkinson's

Droxidopa

Norepinephrine precursor

converted to NE

converted directly to NE by aromatic amino acid decarboxylase

Reserprine

Vesicular monoamine transporter (VMAT) inhibitor

Prevents NE and Epi to be packed

into vesicles by VMAT

causes catecholamine storage depletion

Guanethidine; Bretylium; Guanadrel

Adrenergic neuron blocker

Disrupts NE Vesicular storage

NE gets falsely replaced by the drugs in

the vesicles -> depletion

Tyramine; Ephedrine; Amphetamines

Mixed direct + Indirect sympathomimetic

Promotes NE release

Displaces NE from Synaptic vesicles ->

Increased NE concentration in cytoplasm -> reverse (efflux) NET transport -> high extracellular NE

Selegiline

Monoamine oxidase (MAO) inhibitor

Reduces catabolism of NE and Epi

Increased extracellular NE - > increased reverse (efflux) through NET

Doloxetine

NET inhibitor

BLOCKS NE Transporter

↓ NE reuptake -> ↑ Extracellular NE

Phenylephrine (Sudafed PE)

a1 receptor agonist

a1 -> Gq

Gq-> ↑ ca2+, IP3, DAG; Vesicular contraction;

decongestant; pupillary dilation

Prazosin

a1 receptor antagonist

Blocks a1 -> Gq

Used for hypertension

Clonidine

a2 agonist

a2 -> Gi/o

G i -> ↓ andylate cyclase, ↓ CAMP -> decreased presynaptic neurotransmitter release; hypertension treatment

Isoproterenol

generic B agonist

B -> Gs

Gs -> ↑ adenylate cyclase, ↑ CAMP

Propanolol

generic B antagonist

BLOCKS B receptors

reduces fight/flight symptoms

Bobutamine

B1 agonist

B1 -> Gs (Heart)

Selective to heart -> ↑ HR and contractility

Atenolol

B1 antagonist

Blocks B1

selective to heart -> ↓ Sympathetic stimulation ie chronic angina

Salmeterol

B2 agonist

B2 -> Gs (Lungs)

selective to lungs -> bronchodilation