DRUG MOA and INDICATION ADVERSE EFFECTS NOTABLE PROPERTIES
1.AUTONOMIC DRUGS
Cholinomimetics
A. Direct Acting Choline
Esters
i. Acetylcholine Muscarinic agonist; activates M1 through M3 CNS stimulation, miosis, very short lived DOA: 5-30sec,
receptors in all peripheral tissues. Results to cyclospasm, brochoconstriction, apidly hydrolyzed by AChE; acts
increased secretion, smooth muscle contraction excessive GI and GU smooth on both M and N receptors
(except in vascular smooth muscles where it muscle contraction, increased
causes relaxation) and changes in heart rate secretory activity of sweat gland,
airways etc, vasodilation
ii.Betanechol Muscarinic agonist; activates M1 through M3 Cylospasm, diarrhea, urinary Results in smooth muscle
receptors in all peripheral tissues (same as Ach) ; urgency, vasodilation, reflex contraction except in vascular
for Bladder and bowel atony tachycardia, sweating smooth muscles where it
causes relaxation; resistant to
AChE, orally active, act on M
receptors only
iii. Carbachol Nonselective muscarinic and nicotinic agonist; Cylospasm, diarrhea, urinary acts on both M and N
similar to betanechol; used topically for glaucoma urgency, vasodilation, reflex receptors, DOA: 30mins-2hrs
treatment tachycardia, sweating
B. Direct Acting
Muscarinic Alkaloids
i. Pilocarpine Partial muscarinic agonist; used for treatment of Miosis, blurring of vision good lipid solubility compared
Glaucoma, Sjogren's syndrome and Sicca to choline esters
syndrome
C. Direct Acting Nicotinic Agonists
i. Nicotine Agonist at both NN and NM receptos; activates Generalized ganglionic Able to enter the CNS and
autonomic post ganglionic neurons (both stimulation (hypertension, activates NN receptors ; DOA:
sympathetic and parasympathetic) and skeletal tachycardia, nausea, vomiting, 1-6h only
muscle neuromuscular end plates ; for Smoking diarrhea)
Cessation
ii. Varenicline Selective partial agonist at nicotinic receptors; Generalized ganglionic longer DOA than nicotine: 12-
used exclusively for smoking cessation stimulation (hypertension, 24h
tachycardia, nausea, vomiting,
diarrhea)
D. Short Acting Cholinesterase Inhibitor (Alcohol)
i. Edrophonium Binds briefly to active site of acetylcholinesterase Miosis, salivation, nausea, parenteral, very short lived
(AChE) and prevents access of acetylcholine (Ach); vomiting, diarrhea, bradycardia DOA: 5-15min
Amplifies all actions of Ach; increases
parasympathetic activity and somatic
neuromuscular transmission ; for Myasthenia
gravis diagnosis (Tensilon test)
E. Intermediate Acting Cholinesterase Inhbitors (Carbamates)
i. Neostigmine Forms covalent bonds with AChE, but is hydrolyzed Miosis, salivation, nausea, poor lipid solubility, oral, DOA:
and released; Longer acting than Edrophonium ; vomiting, diarrhea, bradycardia 30min-2h
for Myasthenia gravis treatment; reversal of
nondepolarizing muscular blockade, Ogilvie
syndrome
ii. Pyridostigmine Longer acting effect compared to Neostigmine Miosis, salivation, nausea, poor lipid solubility, oral, DOA:
vomiting, diarrhea, bradycardia 4-8h
iii. Physostigmine Natural alkaloid tertiary amine, similar to Miosis, salivation, nausea, good lipid solubility: able to
neostigmine vomiting, diarrhea, bradycardia enter the CNS, DOA: 4-8h
F. Long Acting Cholinesterase Inhibitors (Organophosphates)
i. Echothiophate Similar to neostigmine but with slower release Miosis, salivation, nausea, moderate lipid solubiliy, DOA:
vomiting, diarrhea, bradycardia 2-7days
ii. Malathion, malathion: scabicide, parathion: insecticide Miosis, salivation, nausea, high lipid solubiliy, DOA: 7-30
Parathion vomiting, diarrhea, bradycardia days
Cholinoceptor Blocking
Drugs
i. Scopolamine Competitively blocks all muscarinic receptors, Drowsiness, blurring of vision, dry known as Hyoscine-N-Butyl-
antagonizes histamine and serotonin ; for motion eyes, constipation, dry mouth, Bromide (Buscopan)
sickness, dec. acid secretion in the GIT urinary retention
ii. Atropine Nonselective competitive antagonism at all Tachycardia, mydriasis, DOC for organophosphate
muscarinic receptors in the CNS and peripheral cyloplegia, skin flushing, delirium, poisoning; notorious for
tissues; causes mydriasis and cycloplegia; hallucinations, urinary retention, causing hyperthermia
mandatory antidote for severe cholinesterase constipation
inhibitor poisoning ; Mydriatic, cycloplegic,
antidote for organophosphate poisoning (DOC), for
, vi. Tropicamide Similar to atropine but with the shortest duration shorter DOA among
of action (15-60min); Mydriatic, cycloplegic in eye cholineceptor blockers (15-
examinations 60min)
vii. Ipratropium Competitive nonselective antagonist at muscarinic Dry mouth, cough, nasal dryness not as effective as SABAs but
receptors ; for BA and COPD less tachycardia and arrhythmia
; few muscarinic effects outside
the lungs
viii. Tiotropium Similar to Ipratropium but with longer duration of Dry mouth, cough, nasal dryness not as effective as SABAs but
action less tachycardia and arrhythmia
; few muscarinic effects outside
the lungs
ix. Oxybutinin Nonselective muscarinic antagonist which reduces Tachycardia, mydriasis, for urinary urgency and
detrussor smooth muscle tone spasms ; for cyloplegia, skin flushing, delirium, incontinence
decreasing urgency in mild cystitis and dec. hallucinations, urinary retention,
bladder spasm after urologic surgery constipation
x. Pralidoxime Regenerates active acetylcholinesterase; can muscle weakness Must be administered before 6-
relieve skeletal muscle and endplate block ; Usual 8 hours of organophosphate
antidote for early stage cholinesterase inhibitor bond with cholinesterase
poisoning occurs ; has oxime group which
has high affinity for phosphorus
xi. Hexamethonium, Competitively blocks all Nn nicotinic Ach receptors Postural hypotension, dry mouth, first successful agents in
Mecamylamine, ; for Hypertensive emergencies (obsolete) blurred vision, constipation, treating HTN
Trimethaptan sexual dysfunction
Sympathomimetics
i. Epinephrine Non-selective, direct acting sympathomimetic; Hypertension, tachycardia, DOC for Anaphylaxis ; inactive
activates A and B adrenergic receptors; A1 - ischemia, hyperglycemia per orem ; do not enter CNS
vasoconstriction and increased BP; B1 - increased significantly ; short DOA
HR, conduction and contractility; B2 -
bronchodilatation ; used for Cardiac arrest,
anaphylaxis, asthma, COPD, Hemostasis
ii. Norepinephrine Non-selective, direct acting sympathomimetic; Extreme vasospasm, tissue Compensatory vagal reflexes
activates A and B adrenergic receptors; A1 - necrosis, excessive BP increase, tend to overcome the direct
vasoconstriction and increased BP; B1 - increased arrhythmias, infarction, reflex postive chronotropic effects ;
HR, conduction and contractility; B2 - bradycardia alpha activity > beta activity;
bronchodilatation ; used for Neurogenic shock, inactive per orem ; do not
cardiogenic shock enter CNS significantly ; short
DOA
iii. Dopamine Non-selective, direct acting sympathomimetic; Cardiovascular disturbances, inactive per orem ; do not
activates A, B and D1 adrenergic receptors; A1 - arrhythmias enter CNS significantly ; short
vasoconstriction and increased BP; B1 - increased DOA; very effective in renal
HR, conduction and contractility; D1 - vasodilation failure associated with shock
in splanchnic and renal blood vessels ; for
cardiogenic Shock and heart failure
iv. Isoproterenol Beta nonselective sympathomimetic; Cardiovascular disturbances, synthetic catecholamine, not
nonselectively activates B adrenergic receptors; B1 arrhythmias readily taken up into nerve
- increased HR, conduction and contractility; B2- endings
bronchodilatation ; for Asthma
vi. Phenylephrine A1 agonist used for short term maintenance of BP Rebound nasal congestion Mydriasis without cycloplegia
in acute hypotension; also used intranasally to (Rhinitis medicamentosa),
produce local vasoconstriction as a decongestant ; hypertension, stroke, MI
mydriatic, for drug-induced hypotension, spinal
shock
vii. Clonidine A2 agonist that inhibits adenylyl cyclase and Sedation, rebound hypertension, When taken per orem, there is
interacts with other intracellular pathways; dry mouth initial inc in BP then will go
marked vasodilation by central sympatholytic down once the drug enters the
effect ; for Hypertension, Cancer pain, opioid CNS
withdrawal
viii. Methyldopa, Central sympatholytics analogous to clonidine ; Sedation, positive Coomb's test Methyldopa - positive Coomb's
Guanfacine and Methyldopa is used for Pre-eclampsia (Hemolytic anemia) test (Hemolytic anemia)
Guanabenz
xi. Apraclonidine, A2 agonist; reserved for ophthalmologic use in eye discomfort, hyperemia and NONE
Brimonidine glaucoma for reduction of intraocular pressure pruritus, blurred vision
xii. Dobutamine B1 agonist that activates adenylyl cyclase, Tachyarrhythmia, Hypertension, Beta1 selective
increasing myocardial contractility; with positive Eosinophilic myocarditis,
inotropic effect ; Clinically used for cardiogenic Premature ventricular beats,
shock and acute heart failure Angina, Dyspnea, Fever,
Headache, Nausea, Palpitation
xiii. B2 agonist with adenylyl cyclase activation; results Nausea , Fever, Bronchospasm, Rapid development of
Albuterol/Salbutamol to bronchial smooth muscle dilation ; for Bronchial Vomiting, Headache, Dizziness, tolerance; DOC as Asthma
Asthma Cough, Allergic reactions reliever
xiv. Fenoldopam D1 agonist that activates adenylyl cyclase; results Angina, Cardiac dysrhythmia, D1 agonist
to vascular smooth muscle relaxation ; for Dizziness, Flushing, Heart failure,
