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Flashcards in Autonomic Pharmacology 2 Deck (37)
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What drugs block cholinergic transmission at neuromuscular junctions?

Neuromuscular Blocking Drugs


What do neuromuscular blocking drugs act as?


  • Antagonists (non-depolarizing)
  • Agonists (depolarizing)

And inhibit release of ACH


What are the neuromuscular blocking agents?

  • Tubocurarine 
  • Succinylcholine
  • Botulinum toxin


What are some characteristics of Curare (d-tubocurarine)?

  • "aarow poisons"
  • Originally used as skeletal muscle relaxants
  • Depolarization of membrane is inhibited and muscle contraction is blocked
  • Causes weakness of skeletal muscles


How can competitive blockers be overcome?

By administration of cholinesterase inhibitors


What are some characteristics of succinylcholine?

  • Attaches to nicotinic receptor and like ACH, results in depolarization
    • Constant stimulation of receptor causes sodium channel to open, producing depolarization
  • Flaccid paralysis


With succinylcholine, how long does the paraylsis last?

Only a few minutes because drug is broken down by plasma cholinesterase


What is succinylcholine used for?

  • Endotracheal intubation
  • Relax skeletal muscles during surgery


What does Botulinum Toxin do and what is it used for?

  • Prevents calcium-dependedn release of ACH
  • Produces state of denervation
  • For muscles tics, muscle disorders, cosmetic procedures


What do ganglionic blocking agents do?

  • Inhibit nicotinic receptors, so blocks nuerotransmission in both PANS and SANS
    • Nicotine
    • Trimethaphan
    • Hexamethonium


What does nicotine do?

  • Low doses - stimulation due to depolarization
  • High doses - no response at nicotinic receptors, but stimulates muscarinic receptors
  • Respiratory paralysis, increase BP, HR, GI motility and secretions
  • Indication: tobacco cessation therapy, insecticide


What type of drugs act at receptors of the sympathetic nervous system?

Adrenergic drugs


What drugs fall under the adrenergic drugs category?

  • Endogenous
    • Epinephrine - adrenal medulla
    • Norepinephrine - terminal nerve endings
    • Dopamine - brian, splanchnic, renal vasculature
  • Exogenous
    • isoproternol


What are the different types of adrenergic receptors?

Alpha & Beta


What are the subtypes of Adrenergic drugs?

  • Direct acting - produce effects by directly stimulating receptor
  • Indirect acting - cause release of endogenous norepinephrine, which produces response
  • Mixed action - either stimulate the receptor directly or cause release of norepinephrine


What does stimulation of Alpha Receptors cause?

  • Vasoconstriction of vessels in skin (pale when scared)
  • Protects you from bleeding if skin is damaged during trauma ("fight" response)
  • Smooth muscle contraction


What does stimulation of Beta-1 Receptors cause?

  • Cardiac stimulation
  • Increased rate and force of contraction
  • Breakdown glycogen to increase glucose (need energy during fight or flight)


What does stimulation of Beta-2 Receptors cause?

  • Smooth muscle relaxation
  • Vasodilation of vessels in skeletal muscle
  • Bronchodilation


What do the adrenergic agonists (sympathomimetics) do?

  • CNS excitation
  • Increased peripheral resistance
  • Increased blood pressure
  • Dilates pupils
  • Ease breathing
  • Xerostomia


What are the clinical uses for adrenergic agonists?

  • Vasoconstriction - (epinephrine) prolongs anesthetics and produce hemostasis
  • Decongestants - vasoconstriction of blood vessels in nose
  • Treatment of shock - elevate low BP
  • Treatment of cardiac arrest - epinephrine jump starts heart
  • Asthma & emphysema - bronchodilation
  • CNS stimulation - amphetamines (stimulants) used to treat ADD/ADHD


What are some popular adrenergic agonists (non-catecholamines)?

  • Albuterol
  • Amphetamines
  • Clonidine
  • Dopamine
  • Oxymetazoline
  • Phenylephrine
  • Phentermine
  • Pseudoephedrine
  • Tetrahydrozoline


What are some characteristics of Albuterol?

  • Beta2 adrenergic agonist
  • Potent bronchodilator
  • "Rescue drug" - asthma & COPD
  • Incuded in all dental office emergency kits for managing acute asthma attack


What are the side effects of Adrenergic Agonists?

  • Anxiety/irritability
  • Tremors
  • Cardiac arrhythmias (tachycardia)
  • Hypertension
  • Constipation
  • Urinary retention


What do Alpha Antagonists (blockers) do?

  • Block vasoconstriction in skin
  • Decrease total peripheral resistance
  • Decrease blood pressure
  • Reverse dilation of pupils


What are the uses of Alpha Antagonists (blockers)?

  • Second line agents for the treatment of hypertension
  • Treatment of peripheral vascular disease
  • Diagnosis and treatment of pheochromocytoma
  • Treatment of benign prostatic hypertrophy


Who are the main users of alpha1 - blockers (Alpha antagonists) and for what primary reasons?

Old Men!

  • Hypertension
  • Benign prostatic hypertrophy


What alpha antagonist reverses dental anesthesia??

phentolamine (OraVerse) 



What are the popular Alpha Antagonists (blockers)?


All end in ...sin

  • prazosin (Minipress)
  • terazosin (Hytrin)
  • doxazosin (Cardura)


What are beta blockers used primarily for?

Beta1 effect - on the heart


What's the difference between selective and non-selective beta blockers (antagonists)?

  • Selective blockers - block only Beta1 receptors in heart and blood vessels
  • Non-selective blockers - block both Beta1 and Beta2 receptors in lungs (beta2)