Create
Learn
Share

Drugs - Autonomic Nervous System + Respiratory System

rename
shaile's version from 2015-05-17 21:00

Sympathomimetics

DrugAction
Epinephrineb1&b2 > a1, a2
Norepinephrinea1
Isoproterenolb1&b2
Phenylpherinea1, a2
Albuterolb2
Dobutamineb1
Dopaminemedium dose = b1, high dose = a1 (shock & renal failure)
memorize

ANS Drugs

 

Cholinomimetics (stim parasymp, sweating, and somatic activity)

 

Direct agonists
DrugApplicationNotes
Bethanecholpostop and neurogenic ileus and urinary retensionactivates bowel/bladder smooth muscle, resistant to AchE
NOT in bowel obstruction (proximal peristalsis--> obstruction), more so w/Diabetic gastric paralysis
Carbacholrelieve intraocular pressure glaucoma, pupillary contraction-
Pilocarpinestim sweat, tears, salivacontracts ciliary muscle of eye (open angle), pupillary sphincter (closed angle)= OPEN and CLOSED angle GLAUCOMA resistant to AchE
Methacholinechallenge test for asthma diagstim M3 receptor--> bronchiole hyperreactivity
memorize

 

Indirect agonists (anticholinesterases)
Poisoning sxs - Diarrhea, Urination, Miosis, Bronchospasm, Bradycardia, Excitation of skeletal muscle and CNS, Lacrimation, Sweating, Salivation (and abdom cramping) = DUMBBELSS -> atropine + pralidoxime is antidote.
DrugApplicationNotes
Neostigminepostop and neurogenic ileus and urinary retension, myasthenia gravis, postop reversal of NMJ blockinc endo ACh, no CNS entry
Pyridostigminemyasthenia gravis (long-acting)inc endo ACh, inc strength, no CNS entry
Edrophoniumdiag myasthenia gravis (super short acting)inc endo ACh
Physostigmineglaucoma, atropine overdoseinc endo ACh, crosses BBB
Echothiophateglaucomainc endo ACh
memorize

 

Muscarinic antagonists (antagonizes parasymp, sweat glands)
DrugOrgan systemNotes
Atropine, homatropine, tropicamideeyeproduce mydriasis and cycloplegia (paralysis of ciliary muscles)
BenztropineCNSParkinson's disease
ScopolamineCNSmotion sickness
Ipratropiumrespiratoryasthma, COPD
OxybutyninGUreduce urgency and bladder spasms
Methscopolamine, pirenzepine, propanthelineGIpeptic ulcer treatment
memorize

 

Nicotinic antagonists - Hexamethonium
Use -> ganglionic blocker, prevent vagal reflex responses to changes in BP (reflex tachy due to NE)
Toxicity -> orthostatic HTN, blurred vision, constipation, sexual dysfunction

 

Sympathomimetics (action similar to NE)
Direct sympathomimetics
DrugApplicationMechanism/selectivity
Epinephrineanaphylaxis, glaucoma (open angle), asthma, hypoptensiona1, a2, b1, b2. selective for b1 at low doses
NEhypotensiona1, a2 > b1
IsoproterenolAV blockb1=b2
Dopamineshock (inc renal perfusion), heart failureD1 = D2 >b>a, inotropic (inc muscle contraction strength) and chronotropic (inc HR)
Dobutamineshock, heart failure, cardiac stress testb1 > b2, inotropic but not chronotropic
Phenylephrinepupillary dilation, vasoconstriction, nasal decongesta1 > a2
Metaproterenol, albuterol, salmeterol, terbutalinemeta and albuterol for acute asthma, salm for long-term asthma, terb to reduce premature uterine contractionsselective b2 agonists (b2 > b1)
Ritodrinereduce premature urterine contractionsb2
memorize

 

Indirect sympathomimetics
DrugApplicationMechanism/selectivity
Amphetaminenarcolepsy, obesity, ADHDreleases stored catecholamines
Ephedrinenasal decongestion, urinary incontinence, hypotensionreleases stored catecholamines
Cocainevasoconstriction and local anesthesiauptake inhibitor
memorize

 

Sympathoplegics (inhibits post-ganglionic SNS function)
Clonidine, a-methyldopa - centrally acting a2-agonists, dec central adrenergic outflow
Application - treat hypertension, esp with renal disease (you can decrease BP without dec blood flow to kidney)

 

Alpha blockers
DrugApplicationToxicity
(non-selective)
Phenoxybenzamine (irreversible) and phentolamine (reversible)pheochromocytoma (use irreversible blocker before removing tumor, since high levels of released catecholamines will not be able to overcome blockage)orthostatic hypotension, reflex tachyardia
(a1-selective - zosin ending)
Prazosin, terazosin, doxazosinhypertension, urinary retention in BPH1st dose orthostatic hypotension, dizziness, headache
(a2-selective)
Mirtazapinedepressionsedation, inc serum cholesterol, inc appetite
memorize

 

Beta blockers
Toxicity - impotence, asthma exacerbation, CV(bradycardia, AV block, CHF), CNS(sedation, sleep alterations), caution in diabetics
Mnemonic - drugs A-M are b1 selective, drugs N-Z are nonselective (exceptions are labetalol and carvedilol, the only 2 that are both a and b blockers)
DrugSelectivity of antagonism
propranololb1=b2
timolol b1=b2
nadololb1=b2
pindololb1=b2 (partial b agonist)
labetalolb1=b2 (also a blocker)
acebutololb1>b2 (partial b agonist)
betaxololb1>b2
esmololb1>b2 (short acting)
atenololb1>b2
metoprololb1>b2
carvedilola = b
labetalola = b
pindolol, acetutololpartial b agonists
memorize

 

Application of beta-blockers
ApplicationEffect
hypertensiondec CO, dec renin (b-receptor blockade on JGA cells)
angina pectorisdec HR, dec contractility -> result in dec O2 consumption
MIdec mortality
superior vent tachy (propranolol, esmolol)dec AV conduction velocity (class II antiarrhythmic)
CHFslows progression of chronic heart failure
glaucoma (timolol)dec secretion of aqueous humor
memorize

Pulmonary System Drugs

H1 blockers

DrugMechanismUseSE
Diphenhydramine (benadryl), Chloropheniramine1st gen, reversible H1 histamine receptor blockerallergies, sleep aidcross BBB --> sedation
Loratadine2nd genration, reversible H1 histamine receptor blockerallergyno sedation
memorize

Asthma drugs

DrugMechanismUseSE
Albuterolβ2 agonist, vasodilation, relax smooth muscleacute asthma attachn/a
Salmeterolβ2 agonist, vasodilation, relax smooth musclelong acting, for prophylaxistremors and arrhythmias
Theophyllinebronchodilation by ↓ phosphodiesterase = ↑cAMPrarely used for asthma b/c narrow TIcardiotoxicity, neurotoxocity, blocks adenosine
Ipratropiumblocks ACh receptorsasthma & COPD, long actingn/a
Cromolyn sodiumbinds to mast cells and blocks histamine releaseprophylaxis for asthman/a
Beclomethasone/Prednisoneglucocorticoids, ↓ IL; ↓ NF-kB = ↓ immune response1st line therapy for chronic asthmacushing's syndrome
Montelukastblocks LTC4,LTD4,LTE4 receptorsaspirin induced asthman/a
Zileutonblocks LOX = ↓ leukotrienes (LTC4,LTD4,LTE4)aspirin induced asthman/a
Omalizumabmab against IgEused in asthma resistant to inhaled steroids and long-acting β2 agonist.
memorize

Others

DrugMechanismUseSE
Guaifenesinthins mucus, does not suppress cough reflex, found in Robitussinthinning mucusn/a
N-acetylcysteineloosen mucus plugs in cystic fibrosis patients`, also antidote for acetaminophen OD. Regenerates glutathione~cystic fibrosis ptxn/a
Bosentan↓ endothelin-1 = causes vasodilation (endothelin = secreted by endothelium cells when damaged to induce vasoconstriction, limit loss of O2)tx for pulmonary hypertensionn/a
Prostaglandins↓ bronch tone and ↓ vaso tone (vasodilation)
Dextromethorphanprevents cough (↓ NMDA glutamate receptors), codeine analog. "Mucinex DM" --> DM = dextromethorphanstop coughabuse potential, if OD = tx w/ Naloxone
Pseduoephedrineα-agonist (makes you dry)nasal decongestants --> ↓ edema. Also a stimulantHTN, CNS anxiety
MethacholineAch receptor agonistasthma challenge test (asthma ptx react to low doses vs. normal ptx need higher doses)n/a
memorize