Autonomic Drugs Flashcards
Mydriasis can be caused by contraction of the radial fibers of the iris, these smooth muscle cells have _______ receptors
Alpha receptors
- Phenylephrine (selective adrenoceptors)
Minoxidil is a powerful arteriolar vasodilator that does not act on autonomic receptors. What are the following effects?
Tachycardia and increased cardiac contractility
- Because of the compensatory responses, a drug that directly decreases blood pressure through a decrease in peripheral vascular resistance will cause a reflex increase in sympathetic outflow
- Heart rate and cardiac force will increase
Full activation of the parasympathetic nerves is likely to produce ____________
- pupillary constrictor muscle (Miosis)
- bronchial and intestinal muscle contration
- bradycardia
Norepinephrine acts at presynaptic _________adrenoreceptors and postsynaptic ___________ adrenporecptors
Alpha 2
Alpha 1
ganglion blockade results in ______ blood pressure, bowel activity and sweating
Decreased
- Because the parasympathetic system dominates the pupil and SA node, it will cause mydriasis and tachycardia
The nerves innervating the pupillary constrictor muscle are __________________ cholinergic nerve
postganglionic parasympathetic
Pupillary muscle dilator contains__________
Alpha 1 adrenoceptors
Botulinum toxin impairs all types of ____________ transmission
Cholinergic
- including transmission at ganglionic synapses and somatic motor nerve endings
- prevents discharge of vesicular transmitter content from cholinergic nerve endings
- cyclop;egia
primary neurotransmitter agent normally released in the sinoatrial node of the heart in response to a blood pressure_________-
Acetylcholine
The _________ transports norepinephrine back into the nerve ending after release and is blocked by cocaine
Reuptake carrier
- Amphetamine is a substrate of NET but does not block it
______ and ______ block transporters in cholinergic nerves
Hemicholinium abd vesamicol
sympathomimetic drug that facilitates the release of catecholamines from adrenergic nerve endings
Amphetamine
Bacterial toxin that enzymatically disables release of acetylcholine from cholinergic nerve endings
Botulinum toxin
Important central nervous system transmitter with some peripheral effects (renal vasodilation, cardiac stimulation)
Dopamine
Research drug the inhibits transport choline into cholinergic nerve endings
Hemicholiniums
research drug that blocks all ANS ganglia and prevents autonomic compensatory reflexes
Hexamethonium
Inhibitor of tyrosine hydroxylase, the rate limiting enzyme in NE synthesis
Metyrosine
Primary transmitter at most sympathetic postganglionic nerve endings; important CNS transmitter
Norepinephrine
Drugs that inhibits VMAT, transported odf dopamine and norepinephrine into transmitter vesicles of adrenergic nerves
Reserpine
Toxins that block sodium channel and therby limit transmission in all nerve fibers
tetrodoxin, saxitoxin
Drug that inhibits VAT, transported of acetylcholine into its transmitter vescles
Vesamicol
Neostigmine and bethanechol in moderate dosage have different effects on the ____________
Vascular endothelium
- Neostigmine
- acts on the enzyme cholinesterase which is present at all cholinergic synapses
- increases acetylcholine effects at nicotinic junctions
- Bethanechol
- direct acting agent that activates muscarinic receptors regardless of wheter the receptors are innervated or not
- The muscarinic receptors on vascular endothelial cells are not innervated and responds only to direct-acting drugs
Parathion
- activated by conversion to -oxon derivatives
- lessstable than halogenated hydrocarbon insecticides of the DDT
- less permanent in the environment
- More toxic than malathion
- very lipid soluble
- rapidly absorbed through the lungs and skin
Best drug for distinguishing between myasthenia crisis (Insufficient therapy) and cholinergic crisis
Edrophonium
- indirect acting
- Cholinergic crisis would be worsened by a cholinomimetic, we choose the shortest-acting cholinesterase inhibitor
most important cause of acute deaths in organophosphate poisoning
respiratory failure from neuromuscular paralysis or CNS deptession
Cholinesterase inhibition is typically associated with ___________
bowel activity (diarrhea)
- Pyridostigmine
- neostigmine
- prototypic carbamate
- AChE inhibitors
Parasympathetic nerve stimulation and a slow infusion of bethanechol will each __________
Increase bronchial smooth muscle tone
direct acting cholinomimetic that is lipid soluble and is used to facilitate smoking cessation
Verenicline
Muscarinic cholinoceptor agonists
- accomondation and cyclospasm
- for acute closure glaucoma
- increased outflow of aqueous and decreased intraocular pressure
- bronchospasm
- no effect on neuromuscular transmission
- sweating
Cholinomimetic with little or no vascular effect, little or no CNS effect and a duration of action of about 2-4 h
Neostigmine
- indirect acting (no vascular effect changes)
- quaternary (charged) substance with poor lipid solubility and little or no CNS
primary second-messenger process in the contraction of the ciliary muscle when focusing in near objects
IP3 (inosital 1,4,5 triphosphate)
- CHolinomimetics cause smooth muscle contraction
- through an action on M3, Gq-coupled receptors resulting in the release of intracellular calcium
Direct acting muscarinic agonists
-
Bethanechol
- Bladder and bowel atony, for example, after surgery or spinal cord injury
- poor lipid solubility
-
Pilocarpine
- sjoren’s syndrome (increases salivation). Was used in glaucoma (causes miosis, cyclospasm)
- good lipid solubility
-
Muscarine
- alkaloid found in mushrooms
- low lipid solubility but readily absorbed from gut
Direct acting nicotinic agonists
-
Nicotine
- Activates all nicotinic receptors, opens Na-K channels in ganglia and neuromuscular end plates
-
Varenicline
- partial agonists at N receptors
- smoking cessation
-
Succinylcholine
- N-receptor agonist, moderately selective for neuromuscular end plate
- initial muscle spasm and postopertaive pain
- prolonged action in persons abnormal butyrylcholinesterase
Indirect acting alcohol
- Edrophonium
- inhibitor cholinesterase
- amplifier of endogenously released ACh
- Reversal of Nm block nondepolarizing drugs
Indirect acting cabimates
-
Neostigmine
- like edrophonium plus small direct nicotinic agonist action
- Reversal of Nm block
-
Pyridostigmine
- like edrophoniu,
- treatment for myasthenia
-
Physostigmine
- like edrophonium
- Reversal of severe atropine posioning (IV). Occasionally used in acute glaucoma (topical)
Atropine causes __________ (HR)
Tachycardia (Overdose)
Bradycardia (small doses)
Most dangerous effect if beladonna alkalids in infants and toddlers
Hyperthermia
Atropine blocks _______ receptors and inhibits ________ effects
Muscarinic
parasympathomimetic
______ can induce both parasympathomimetic and sympathomimetic reffects by virtue of it ganglion stimualting actions
Nicotine
Distinguish between an overdose of a ganglion blocker versus a muscarinic blocker?
Postural hypotension
decreased DAG in salivary gland tissue is an effect of
antimuscarinic drug
_______causes vasodialtion by directly activating muscarinic receptors on the endothelium of blood vessels. this effect can be blocked by atropine
Bethanechol
_____has very high affinity for the phosphorous atom in organophosphate insecticides
Pralidoxime
Antimuscarinic, nonselective
Atropine
- Competitive pharmacologic antagonist at all M receptors
- Mydriatic, cycloplegic
- antidote for cholinesterase inhibitor toxicity
- lipid soluble
Pirenzepine, telenzepine
Significant M1 selectivity
Antinicotinic ganglion blockers
Hexamethonium
selective Nn of receptors
Pupillary dialtion but not cycloplegia
Phenyelphrine
- antimuscarinics are mydriatic and cycloplegic
- alpha-sympathomimetic agonists are Mydriatic only
dual blood pressure effects
Clonidine
- direct alpha agonist, vasoconstrictor effect
- but when given for a wekk, it is accumulated in a blood pressure controllingc center
_____cause decrease in diastolic BP and little change in systolic BP. LArge increase in pulse pressure
Isoproterenol
- The decrease in diastolic blood pressure sugests that the drug decreased vascular resistance, that is it must have significant muscarinic or B agonsit effects
Epinephrine
a1, a2, B1, B2, B3 agonist
Norepinephrine
a1, a1, B1, B3
isoproternol
B1, B2, B3 agonist
used as nebulizer and IV (in AV block)
Dobutamine
B1 agonist’
Primarily used in acute failure to increase cardiac output
Effects of epinephrine would be blocked by prasozin but not metoprolol
Mydriasis
Nonselective alpha blocker
Phentolamine
Phenoxybenzamine
Alpha 1 selective alpha blocker
Prasozin
Alpha 2 blockers
Yohimbine