FA General Pharmacology Flashcards
Cholinomimetic Agents
Direct: Bethanecol, Carbachol, Pilocarpine, Methacholine
Indirect: Neostigmine, Pyridostigmine, Physostigmine, Donepezil, Rivastigmine, Galantamine, Edrophonium
Cholinomimetic Agent Toxicity
Watch for exacerbation of COPD, asthma, and peptic ulcers when given to susceptible patients
Bethanecol Use
Postoperative ileus, neurogenic ileus, and urinary retention
Bethanecol Mechanism
Activates bowel and bladder smooth muscle; resistant to AChE.
Carbachol Use
Glaucoma, pupillary constriction, and relief of intraocular pressure
Carbachol Mechanism
Carbon copy of acetylcholine
Pilocarpine Use
Potent stimulator of sweat, tears, and saliva. Open-angle and closed-angle glaucoma.
Pilocarpine Mechanism
Contracts ciliary muscle of eye (open-angle glaucoma), pupillary sphincter (closed-angle glaucoma); resistant to AChE.
Methacholine Use
Challenge test for diagnosis of asthma
Methacholine Mechanism
Stimulates muscarinic receptors in airway when
inhaled
Neostigmine Use
Postoperative and neurogenic ileus and urinary retention, myasthenia gravis, reversal of neuromuscular junction blockade (postoperative)
Neostigmine Mechanism
↑ endogenous ACh.
Neo CNS = No CNS penetration.
Pyridostigmine Use
Myasthenia gravis (long acting); does not penetrate CNS
Pyridostigmine Mechanism
↑ endogenous ACh; ↑ strength. Pyridostigmine
gets rid of myasthenia gravis.
Physostigmine Use
Anticholinergic toxicity (crosses blood-brain barrier → CNS)
Physostigmine Mechanism
↑ endogenous ACh. Physostigmine “phyxes”
atropine overdose.
Donepezil, Rivastigmine, Galantamine Use
Alzheimer disease
Donepezil, Rivastigmine, Galantamine Mechanism
↑ endogenous ACh.
Edrophonium Use
Historically, diagnosis of myasthenia gravis (extremely short acting). Myasthenia now diagnosed by anti-AChR Ab (antiacetylcholine receptor antibody) test.
Edrophonium Mechanism
↑ endogenous ACh.
Cholinesterase Inhibitor Poisoning
Often due to organophosphates, such as parathion, that irreversibly inhibit AChE.
Causes DUMBBELSS: Diarrhea, Urination, Miosis,
Bronchospasm, Bradycardia, Excitation
of skeletal muscle and CNS, Lacrimation,
Sweating, and Salivation.
Organophosphates are components of
insecticides; poisoning usually seen in farmers.
Antidote—atropine (competitive inhibitor) +
pralidoxime (regenerates AChE if given early).
Muscarinic Antagonists
Atropine, Homatropine, Tropicamide, Benztropine, Scopolamine, Ipratropium, Tiotropium, Oxybutynin, Darifenacin, Solifenacin, Glycopyrrolate
Eye Muscarinic Antagonists
Atropine, Homatropine, Tropicamide
CNS Muscarinic Antagonists
Benztropine, Scopolamine
Respiratory Muscarinic Antagonists
Ipratropium, Tiotropium
Genitourinary Muscarinic Antagonists
Oxybutynin, Darifenacin, Solifenacin
Gastrointestinal/Respiratory Muscarinic Antagonist
Glycopyrrolate
Atropine, Homatropine, Tropicamide Use
Produce mydriasis and cycloplegia
Benztropine Use
Parkinson disease
Scopolamine Use
Motion sickness
Ipratropium, Tiotropium Use
COPD, asthma
Oxybutynin, Darifenacin, Solifenacin Use
Reduce urgency in mild cystitis and reduce bladder spasms. Other agents: tolterodine, fesoterodine, trospium.
Glycopyrrolate Use
Parenteral: preoperative use to reduce airway secretions.
Oral: drooling, peptic ulcer.
Atropine Mechanism
Muscarinic antagonist.
Atropine Use
Used to treat bradycardia and for ophthalmic applications. ↑ pupil dilation, cycloplegia, ↓ airway secretions, ↓ stomach acid secretion, ↓ gut motility, ↓ urinary urgency in cystitis
Atropine Toxicity
↑ body temperature (due to ↓ sweating); rapid pulse; dry mouth; dry, flushed skin; cycloplegia; constipation; disorientation Can cause acute angle-closure glaucoma in elderly (due to mydriasis), urinary retention in men with prostatic hyperplasia, and hyperthermia in infants
Sympathomimetics
Direct: Epinephrine, Norepinephrine, Isoproterenol, Dopamine, Dobutamine, Phenylephrine, Albuterol, Salmeterol, Terbutaline
Indirect: Amphetamine, Ephedrine, Cocaine
Epinephrine Mechanism
β > α
Epinephrine Use
Anaphylaxis, open angle glaucoma, asthma, hypotension; α effects predominate at high doses
Norepinephrine Mechanism
α1 > α2 > β1
Causes ↑ in systolic and diastolic pressures as a result of α1-mediated vasoconstriction → ↑ mean arterial pressure → bradycardia.
Norepinephrine Use
Hypotension (but ↓ renal perfusion)
Isoproterenol Mechanism
β1 = β2
Isoproterenol (no longer commonly used) has little a effect but causes β2-mediated vasodilation, resulting in ↓ mean arterial pressure and ↑ heart rate through β1 and reflex activity.
Isoproterenol Use
Electrophysiologic evaluation of tachyarrhythmias. Can worsen ischemia.
Dopamine Mechanism
D1 = D2 > β > α
Dopamine Use
Unstable bradycardia, heart failure, shock; inotropic and chronotropic α effects predominate at high doses
Dobutamine Mechanism
β1 > β2, α
Dobutamine Use
Heart failure (inotropic > chronotropic), cardiac stress testing
Phenylephrine Mechanism
α1 > α2
Phenylephrine Use
Hypotension (vasoconstrictor), ocular procedures (mydriatic), rhinitis (decongestant)
Albuterol, Salmeterol, Terbutaline Mechanism
β2 > β1
Albuterol, Salmeterol, Terbutaline Use
Albuterol for acute asthma; salmeterol for longterm asthma or COPD control; terbutaline to reduce premature uterine contractions
Amphetamine Mechanism
Indirect general agonist (sympathetic), reuptake inhibitor, also releases stored catecholamines
Amphetamine Use
Narcolepsy, obesity, attention deficit disorder
Ephedrine Mechanism
Indirect general agonist (sympathetics), releases stored catecholamines
Ephedrine Use
Nasal decongestion, urinary incontinence, hypotension
Cocaine Mechanism
Indirect general agonist (sympathetics), reuptake inhibitor
Cocaine Use
Causes vasoconstriction and local anesthesia;
never give β-blockers if cocaine intoxication is
suspected (can lead to unopposed α1 activation
and extreme hypertension)
Sympatholytics
Clonidine, α-methyldopa
Clonidine Use
Hypertensive urgency (limited situations); does not decrease renal blood flow. ADHD, severe pain, and a variety of off-label indications (e.g. ethanol and opioid withdrawal)
Clonidine Toxicity
CNS depression, bradycardia, hypotension, respiratory depression, and small pupil size
α-methyldopa Use
Hypertension in pregnancy (safe in pregnancy)
α-methyldopa Toxicity
Direct Coombs positive hemolytic anemia, SLE-like syndrome
α-blockers
Non-selective: Phenoxybenzamine (irreversible), Phentolamine (reversible)
α1 selective: Prazosin, Terazosin, Doxazosin, Tamsulosin
α2 selective: Mirtazapine
Non-selective α-blockers
Phenoxybenzamine (irreversible), Phentolamine (reversible)
α1-blockers
Prazosin, Terazosin, Doxazosin, Tamsulosin
α2-blockers
Mirtazapine
Phenoxybenzamine Use
Pheochromocytoma (used preoperatively) to prevent catecholamine (hypertensive) crisis
Phenoxybenzamine Toxicity
Orthostatic hypotension, reflex tachycardia
Phentolamine Use
Give to patients on MAO inhibitors who eat tyramine-containing foods
α1-blocker Use
Urinary symptoms of BPH; PTSD (prazosin); hypertension (except tamsulosin)
α1-blocker Toxicity
1st-dose orthostatic hypotension, dizziness, headache
Mirtazapine Use
Depression
Mirtazapine Toxicity
Sedation, ↑ serum cholesterol, ↑ appetite
β-blockers
Metoprolol, acebutolol, betaxolol, carvedilol, esmolol, atenolol, nadolol, timolol, pindolol, labetalol
β-blocker Use
Angina Pectoris: ↓ heart rate and contractility, resulting in ↓ O2 consumption
MI: β-blockers (metoprolol, carvedilol, and bisoprolol) ↓ mortality
SVT (metoprolol, esmolol): ↓ AV conduction velocity (class II antiarrhythmic)
Hypertension: ↓ cardiac output, ↓ renin secretion (due to β1-receptor blockade on JGA cells)
CHF: Slows progression of chronic failure Glaucoma (timolol): ↓ secretion of aqueous humor