Autonomic Nervous System Drugs

rhawkie's version from 2016-10-24 20:01

Drugs regarding synapses

Question Answer
Transport of choline inhibited by...hemicholinium
VAT transport inhibited by...vesamicol
Neurotransmitter release inhibited by...botulinum toxin
Hydrolyses acetylcholineacetylcholinesterase
Inhibits synthesis of noradrenaline (2)α-methyldopa / metyrosine
Inhibits storage of noradrenalineReserpine
Inhibits release of noradrenaline (2)Guanethidine / Amphetamine
Inhibits receptorbinding of noradrenaline (2)Prazosin (α) / Propranolol (β)
Inhibits receptorbinding of acetylcholine (3)Atropine (M) / Tubocurarine (N) & Trimethaphane (N)

Direct-acting Sympathomimmetics

Question Answer
α-MethyldopaAntihypertensive Drug (α2 Agonist)
ReserpineAntihypertensive Drug (Inhibits vesicular transport of dopamine)
GuanethidineAntihypertensive Drug (Inhibits action potential-induced release of NA)
AdrenalineNon-synthetic sympathomimmetic - Administered in close proximity to heart after cardiac arrest to increase BP
IsoprenalineSynthetic sympathomimmetic - Administered in close proximity to heart after cardiac arrest to increase BP
DobutamineSelective β1-Adrenergic Agonist - Increases heart contracting force: Used in Heart Failure
Orciprenaline (metaproterenol)Selective β2-Adrenergic Agonist - Dilates bronchioli, not methylated by COMT, longer duration (3-4 hours), also stimulates β1 in high doses - Used as bronchodilator
SalbutamolSelective β2-Adrenergic Agonist - Long acting - Used as Bronchodilator
TerbutalineSelective β2-Adrenergic Agonist - Contains resorcinol ring, thus not methylated by COMT, administered orally or by inhalation - Used as a Bronchodilator
SalmeterolSelective β2-Adrenergic Agonist - Long-acting (12 hours), administered by inhalation, onset of action: 10-30min - Used as Bronchodilator
FormoterolSelective β2-Adrenergic Agonist - Long-acting (12 hours), administered by inhalation, onset of action: 1-3min - Used as Bronchodilator

Indirect-acting Sympathomimmetics

Question Answer
PhenylephrineIndirect-acting sympathomimmetic - Potent action on α receptors - Used for: Treatment of Shock, after MI/hypotension during spinal anaesthesia, mydriasis/opthalmic decongestion, nasal drops (vasoconstriction)
EphedrineIndirect-acting sympathomimmetic - Displaces NA, active orally, less CNS stimulation than amphetamine, indirect action can cause tachyphylaxis, suppresses appetite - Used for: Treating hypotension (also local vasoconstrictor)
PhenylpropanolamineIndirect-acting sympathomimmetic - Used as: Nasal decongestant, bronchodilation (like ephedrine, but less CNS stimulation)
AmphetamineIndirect-acting sympathomimmetic (also directly @ high doses) - Liberates NA from vesicles, enters CNS, high abuse potential, anorexigenic - Indication: Narcolepsy, minimal brain dysfunction
Naphazoline and OxymetazolineIndirect-acting sympathomimmetic - Incomplete, little effect - Used for: vasoconstriction (also nasal and eye drops)


Question Answer
Phenoxybenzamine (Haloalkylamines)α-Antagonist - α1 > α2, blocks α2 to certain degree,causing uncontrolled NA release, long duration - Induces vasodilation -> lower BP, but reflex increase in sympathetic stimulation of heart, used to block α effects of phaeochromocytoma
Phentolamine (Imidazolines)α-Antagonist - Close to Phenoxybenzamine. Mode of action faster, duration shorter, α1=α2, reflex increase in β receptor stimulation - Used during surgery of phaeochromocytoma
Prazosin, doxazosin, terazosin (Quinazolines)α-Antagonist - α1, Causes peripheral vasodilation (arterial and venous) - Limited antihypertensive use (short duration, first-dose hypotension & tachyphylaxis), no reflex β stimulation

Beta Antagonists

Question Answer
Propranololβ-Antagonist - β1=β2 - Causes bronchospasm by β2-blockade
Atenololβ1-Antagonist - Partial agonist - Low local anaesthetic activity
Carvedilolβ-Antagonist - Not Partial agonist - Moderate local anaesthetic activity
Labetalolα & β-Antagonist - Partial β2 agonist - Low local anaesthetic activity
Metoprololβ1-Antagonist - Partial agonist - Moderate local anaesthetic activity
Pindololβ-Antagonist - Partial agonist - Moderate local anaesthetic activity
Timololβ-Antagonist - Not partial agonist - Moderate local anaesthetic activity


Question Answer
EdrophoniumQuaternary amine, short duration, Dx of myasthenia gravis, IV = increased muscle S.
NeostigmineQuaternary amine & carbamate, nicotinic agonist (stimulates skeletal m. directly
PhysostigmineTertiary amine & carbamate, crosses BBB, lowers intraocular pressure in glaucoma
Puridostigmine bromide3 - 6 hours, tx of myasthenia gravis

Other Non-Steroidal Anti-inflammatory Drugs (peripherally acting)

Question Answer
DiclofenacModerate potency, moderate risk of GIT disturbances, administered IM
IbuprofenLowest side-effect incidence.
NaproxinMore potent than Ibuprofen, moderate risk of side-effects
Mefenamic acidModerate potency, moderate side-effect risk, diarrhea
IndomethacinMost potent COX2 inhibitor, high incidence of side-effects
PiroxicamLong t1/2, orally, may cause GIT irritation.
MeloxicamSame as piroxicam, more COX2 selective.