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66 Cards in this Set
- Front
- Back
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Where are the muscarinic receptor subtypes located?
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m1: nerves; gastric parietal cells
m2: nerves; cardiac cells; smooth m. m3: lungs; bladder; GI; exocrine glands; eye; smooth m. m4/5: CNS |
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Mnemonic for Gq/i/s?
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Gq (cutesy) HAV 1 M&M
Gi MAD 2s Gs all the rest |
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How can Ach lower BP
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Ach receptors in the vasculature - increased NO - vasodilation
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how does ACh increase urination?
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increases detrusor m tone and relaxes sphincter (both M3)
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Ach causes miosis by:
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contracting the circular m in the iris
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Does bethanechol have muscarinic/nicotinic activity?
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muscarinic Y
nicotinic No |
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What is the affinity of AChE for bethanechol, carbachol and pilocarpine?
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ZERO affinity
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bethanechol clinical use?
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Urinary retention due to denervation of sphincter (diabetes/trauma)
GERD (increased GI motility) |
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carbachol and pilocarpine clinical use?
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miotic agent to reduce IOP in both types of glaucoma
(pilocarpine is DOC) |
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What is the mech of action and clinical use for donepezil, galantamine, rivastigmine, tacrine?
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AChE inhibitors; Alzheimer dementia
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which AChE inhibitors are useless in cholinergic crises?
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neostigmine and pyridostigmine (quaternary amines can't cross BBB)
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what is edrophonium used for?
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AChE inhibitor for diagnosis of myasthenia gravis (vs cholinergic crisis)
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what is the antidote for atropine overdose?
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physostigmine (crosses BBB)
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IRREVERSIBLE AChE inhibitors?
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Also known as organophosphates: sarin, parathion, malathion, echothiophate, isoflurophate
(covalent binding deactivates) |
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counteracts muscarinic/CNS effects of organophosphates
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atropine (outcompetes ACh @ muscarinic receptors) to relieve symptoms
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AChE reactivator
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pralidoxime (2-PAM)
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3 drug classes with antimuscarinic effects:
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-1st gen antihistamines
-TCAs -phenothiazines |
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low vs hi dose atropine
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lo: decreases HR (paradoxical)
hi: increases HR |
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scopolamine (vs atropine); indication
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-longer duration; more CNS potency; blocks short-term memory
-indicated for motion sickness |
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precipitates emergent narrow-angle glaucoma
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-drugs with anticholinergic activity (atropine, scopolamine, etc)
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anticholinergics used for asthma/COPD
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-ipratropium (no effect on airway secretions)
-tiotropium (longer t1/2) |
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three ganglionic blocking agents; indications
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-hexamethonium
-mecamylamine -trimethaphan =lower BP (block symp BV tone AND symp baroreflex); block ANS reflex; smoking cessation (nicotinic block) |
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where do NMBs work?
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nicotinic receptors at the NMJ
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nicotinic receptor structure
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5 subunits; 2a, 3B; TLGI channel (ACh binds btw alpha subunits)
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most common and only depolarizing NMB?
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succinylcholine; used in endotracheal intubation (and electroshock therapy); broken down by PLASMA cholinesterase
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SE of NMB: muscular rigidity; increased O2 consumption/CO2 production; tachycardia; hyperthermia
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malignant hyperthermia
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tx for malignant hyperthermia
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dantrolene (inhibits Ca release from SR)
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mech and prototype nondepolarizing NMB; indication
(other nondepol NMBs) |
tubocurarine; competitive antagonist of ACh @ NMJ (AChE inhibitor is antidote); adjunct to general anesthesia/mech ventilation
(also atracurium (BILE excretion), mivacurium, ROcuronium, pancuronium, vecuronium, pipercuronium) |
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which drugs can act synergistically with nondepolarizing NMBs?
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aminoglycosides (inhibit ACh release from nerve endings due to competition with Ca2+); watch for hi dose, hypocalcemia
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epinephrine synthesis steps
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tyrosine-(tyrosine HOlase)-DOPA
DOPA-(DOPA deCOlase)-dopamine dopamine-(dop B-HOlase)-norepi norepi-(methylation in adrenal medulla)-epinephrine |
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reserpine mech; SE
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-inhibits NE transport from cytoplasm into synaptic vesicles
-SE: depression, sedation |
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cocaine mech
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inhibits NT reuptake into presynaptic neuron
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amphetamine, ephedrine, tyramine mech
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increase NE by entering presynaptic neuron and releasing stored NE
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alpha receptor locations
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a1: vascular smooth muscle; papillary dilator muscle; pilomotor sm m; prostate; heart
a2: postsynaptic CNS adrenoreceptors; pancreatic B-cells; platelets; adrenergic and cholinergic nerve terminals; vascular smooth m; fat cells |
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beta receptor locations
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B1: heart; juxtaglomerular cells
B2: respiratory, uterine and vascular sm m; skeletal m; liver |
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D receptor locations
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D1: smooth m
D2: nerve endings |
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local vs systemic a2 activation
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local: vasoconstriction in vasculature; inc BP
central: inhibition of NE release, overwhelms local effects; dec BP |
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a2 agonists
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clonidine, a-methyldopa, guanabenz, guanfacine, dexmedetomidine
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clonidine indications
dexmedetomidine indications |
HT, severe pain, heroin w/d, nicotine w/d, ethanol dependence, migraines
dex: sedation of intubated and mechanically ventilated pts; prolongation of spinal anesthesia |
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which are more sensitive, alpha or beta receptors?
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B, activated first
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a1 effects
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mydriasis
vasoconstriction dec urination inc glycogenolysis dec renin release ejaculation |
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a2 effects
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central inhibition of NE release
inhibition of insulin release platelet aggregation |
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B1 effects
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inc HR
inc conduction velocity inc force of contraction inc renin release |
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B2 effects
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vasodilation
bronchodilation relaxation of uterine, respiratory, smooth m increased insulin secretion increased K uptake increased glycogenolysis |
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peripheral D1 effects
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vasodilation of coronary, mesenteric, renal vasculature
increased RPF/GFR increased sodium excretion |
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lo vs hi dose epi in vasculature
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lo: B receptors - vasodilation
hi: a receptors - vasoconstriction |
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isoproterenol receptor activation
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B1=B2
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domapine receptor activation
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D>B>a
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dobutamine receptor activation
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B1>B2
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phenylephrine receptor activation
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a1>a2
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dopamine metabolite
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HVA
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dobutamine use
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inc CO in CHF w/o affecting RPF (vs dopamine)
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tyramine source and effects
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found in aged foods
hypertensive crisis in MAOI users |
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mixed action adrenergic agonists
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release stored NE AND hit a/B receptors
ephedrine, pseudoephedrine |
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nonselective competitive alpha antagonist
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phentolamine
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nonselective irreversible antagonist
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phenoxybenzamine
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selective a1 antagonist
indication? |
prazosin
BPH; hypertension (less reflex tachy than nonselective) |
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selective a1A antagonist
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tamsulosin
(less CV SE; for BPH) |
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CNS prejunctional a2 antagonist for postural hypotension and erectile dysfunction
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yohimbine
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CNS prejunctional a2 antagonist for depression
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mirtazapine
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B1 selective antagonists
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acebutolol, atenolol, bisoprolol, betaxolol, esmolol, metoprolol
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nonselective B antagonists
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propranolol, timolol, pindolol, nadolol
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mixed a1/B antagonists
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carvedilol, labetalol
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intrinsic sympathomimetic activity
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drugs act as partial agonists and only work with increased sympathetic drive (exercise eg); less bradycardia, less fx on lipid metabolism
-acebutolol, pindolol |
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tx indications for B blockers
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angina
arrhythmias hypertension CHF (some) thyrotoxicosis glaucoma |
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side effects of propranolol
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increased serum TG and LDL; crosses BBB and causes vivid dreams
(need to be tapered off due to upregulation of B receptors!) |
