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Block 3 Pharmacology
Drugs from Drug List
46
Medical
Professional
02/24/2010

Additional Medical Flashcards

 


 

Cards

Term
Norepinephrine
Definition

Naturally occurring catecholamine

Strong agonist of Alpha and Beta1 Receptors

Weak Agonist of B2 receptors

 

Effects on heart and BP:  Increase Contractility (B1)

Increase Systolic BP

Greatly Increase SVR and Diastolic BP (Alpha1)

Decreases Heart Rate: Baroreceptor Reflex induces strong Vagal Response.

 

Term
Epinephrine
Definition

Naturally Ocurring Catecholamine

Strong Agonist of both Alpha and Beta Receptors


Effects on BP and Heart:

Increase contractility and HR (Increased Systolic Pressure) via B1 receptors

Dilates Skeletal Muscle Arterioles (Decreased SVR and Diastolic Pressure)

Net Increase in MAP (not large enough to strongly activate baroreceptor)

 

Also increases rate of gluconeogenesis and lipolysis via cAMP mech

 


 

 

Term
Tyramine
Definition

A phenylethylamine that can be taken up into nerve terminal and vesicle.

 

Acts indirectely to displace stored norepinephrine from vesicles (acute sympathomimetic effects bc NE leaves via exocytosis)

 

Long-term: reduces Norepinephrine levels and acts as a "false neurotransmitter" (after metabolism to octopamine)

 

Is metabolized by MAO--Increased levels with MAO inhibitors

Term
Amphetamine
Definition

A phenylethylamine that is taken up neuronally and into vesicles.

 

Acts indirectly to displace NE, causing sympathomimetic effects

Term
Cocaine
Definition

Drug of abuse and competive inhibitor of sympathetic neuronal uptake of Norepinephrine (along with tricyclic antidepressants)

 

Potentiates sympathetic neurotransmission (More NE in synapse for longer)

 

Is NOT taken up into Neuron

 

 

Term

Tricyclic Antidepressants

(eg imipramine)

Definition

Competive inhibitor of sympathetic neuronal Norepinephrine uptake (along with cocaine)

 

Potentiates Sympathetic Neuronal transmission--more NE in the synapse for a longer time

 

Is NOT actually taken up into nerve terminal.

Term
Reserpine
Definition

Selective and Irreversible Inhibitor of Vesicular Uptake Mechanism

 

Depletes Intraneuronal Norepinephrine (and Dopamine) levels because NE cannot get into protective vesicles. 

 

Sometimes causes an initial sympathomimetic effect, followed by decrease in BP and loss of cardiovascular reflexes.

 

Acts in both brain and periphery

Term
MAO Inhibitors
Definition

Monamine Oxidase Inhibitors

Action: increase catecholamine levels by reducing rate of metabolism

Ex: Isocarboxazid


Monamine Oxidase is a mitochondrial enzyme that converts catecholamines into adrenergically inactive aldehydes.


Monamine Oxidase is present in liver and GI (processes adrenergically active things in food), and symp. nerve endings (regulates catecholamines in cytosol).


2 isoforms- MAO-A metabolizes serotonin (inhibited for depression treatment); MAO-B metabolizes Dopamine (inhibited for Parkinson's treatment)


Important in Metabolism of Catecholamines (mainly drugs as opposed to naturally occuring catecholamines)

 

[image]

St. John's Wort is a "natural" example

Term
COMT Inhibitors
Definition

Catechol-O-methyltransferase Inhibitors

ACTION: Increase catecholamine levels by inhibiting their metabolism


COMT normally metabolizes and inactivates Epinephrine and Norepinephrine by methylating the meta-OH group (EPI-->metanephrine, NE-->normetanephrine)


Found in kidney and liver


Entacapone is a selective inhibitor (used in conjunction with L-dopa for Parkinson's)

Term
Isoproterenol
Definition

Catecholamine (adrenergic agonist)

 

Strong Beta Agonist

Weak Alpha Agonist


Effects on Heart and BP:

Increases Contractility, HR and Systolic Pressure (B1)

Dilates Abdominal and Skeletal muscle arterioles--decreases SVR (B2)

Effect on BP depends on physiologic state


Strongest Beta Agonist (of NE and EPI)

 

Term
Phenylephrine
Definition

Alpha 1 Agonist

 

Used to for decongestion of mucous membranes in Nose and Eye. 

 

Used to induce mydriasis--acts on radial muscle/iris

 

Also for anti-hypotension.

Term
Clonidine
Definition

Direct-Acting Alpha-2 Agonist


Lacks both hydroxyl groups--Readily passes Blood-Brain Barrier--has CNS effects


Acts on A2 receptors in hypothalamus--causes vasodilation by preventing sympathetic outflow--Anti-hypertensive

 

Treats withdrawal from narcotic addiction (CNS effect)

 


 

 

 

 

Term
Albuterol
Definition

Beta-2 selective agonist--Common treatment of acute, episodic asthma attacks


Oral Inhalation causes bronchodilation via B2


Problems for prophylactic treatment:  Potentially densensitzes airway B2 receptors, reducing effectiveness.

 

 

 

 

 

 

 

 

Term
Salmeterol
Definition

Long-acting partial Beta-2 agonist--useful in maintenence therapy of asthma

 

Does not cause as much desensitization as a full B2 agonist


Combined with inhaled corticosteroids (which treat underlying inflammation)

 

Very Lipophilic--May act on a different population of B2 receptors

Term
Dobutamine
Definition

Drug for short-term treatment of acute heart failure

 

Ionotrophic, but not Chronotrophic (B-1 agonist?)

No effect on peripheral resistance

Term
Drug of Choice in Allergic Hypersensitivity Reactions
Definition

Epinephrine


Via Beta-2, inhibits mast cell degranulation (and thus histamine, bradykinin, etc.)


Prevents glottal and pharyngeal edema


Supports Blood Pressure (counteracts vasodilation from response)

Term
Dopamine
Definition

Weak Beta-1 agonist

 

Used to increase cardiac output

 

Activation of Dopamine receptors on vascular smooth muscle-->increased perfusion of vital organs w/o decrease in BP

 

Effects on HR and BP:

Increases heart rate and contractility (increase systolic)

Decreases peripheral resistance (decrease/constant diastolic)

Increases BP

 

Term
Why not use propanolol in an asthmatic?
Definition
If you induce Beta Blockade with propanolol, B2 agonists will not be effective to treat acute bronchospasm attacks.
Term
Side effects of Beta-1 Blockade
Definition

May induce congestive heart failure

Life-threatening bradycardia

Up-regulating receptors, leading to withdrawal syndrome.

Term
Atenolol
Definition

Specific Beta-1 Antagonist

 

Used for hypertension and congestive heart failure maintenance

 

Much longer half life than Metoprolol

Term
Beta receptor antagonist with intrinsic sympathomimetic activity
Definition

Pindolol and Acebutolol

 

Beta blockade is not "complete" in that the drug causes some sympathoexcitation (ie heart rate is not completely reduced)

Term
Alpha-1 Selective Antagonists
Definition

Tamsulosin, Doxazosin, Terazosin

 

Increases Blood Flow (most tissues) and Decreases BP

 

Improved over non-selective A-antagonists because there is no tachycardia (A-2 autoregulation of NE release)

 

Used for: hypertension and hypertension crisis

Pheochromocytoma (tumor of adrenal medulla-->Increased Catecholamine production)

Congestive Heart Failure

Prostate Hypertrophy

 

 

Term
Treatment for Benign Prostatic Hypertrophy
Definition

Alpha 1 Antagonist

 

Decreases Smooth Muscle Contractions in Neck of Prostate-->Decreased Proliferation

Term
Sumatriptan
Definition

5HT1B/D Receptor (Serotonin) Agonist

 

Acute Treatment of Migraines.

 

Mech?  Cuts off anastomoses via intracranial constriction, preventing ischemia, one of the potentially causes of migraines

 

 

Term
Methacholine
Definition

Direct-Acting Parasympathomimetic Drug (Muscarinic-Selective)

 

Is metabolized by AChE more slowly (one third the rate)

 

Because it is still relatively short-acting, sometimes used to test for bronchial hyperactivity

 

Side Effects: SLUDS, asthma attacks, heart block

Term
Carbachol
Definition

Direct acting Parasympathomimetic (Non-selective nicotinic/muscarinic)

 

Used for topical glaucoma management--iris pulls open canal of Schlemm

 

Not metabolized by AChE, long acting

 

 

Term
General Uses of Parasympathomimetic Drugs
Definition

1. GI atony

2. Nonobstructive Urinary Bladder atony

3.  Glaucoma

4. Myasthenia Gravis

Term
Bethanechol
Definition

Direct Acting Parasympathomimetic Drug (Muscarinic Selective Agonist)

 

Not susceptible to AChE--long acting

 

mainly affects GI and Urinary Bladder at normal doses

Used to increase tone and contractions of above

Term
Pilocarpine
Definition

Natural Plant Alkaloid (muscarinic agonist)

 

Not susceptible to AChE--long acting

 

Treats glaucoma--iris opens canal of Schlemm when constricting pupil

Term
Edrophonium
Definition

Reversible Cholinesterase Inhibitor

 

Very Short Acting--Diagnostic for Myasthenia Gravis

Reverses weakness in MG, not for other neurodegenerative diseases.

 

For dosing:  If Edrophonium reduces weakness in a medicated person-->dose too low

If it does not-->Initial dose is too high and causes weakness via persistent depolarization

 

A Quaternary Alcohol--Ionically associates with AChE, slowing its action

 

Term
Neostigmine
Definition

Reversible AChE Inhibitor

 

Increases gastric motility and secretions

Increases Urinary bladdar contractions

Improves transmission at NMJ


Used for Myasthenia Gravis therapy (longer acting than edrophonium)

Used for Nonobstructive GI issues


Quaternary Amine--Charged and does not cross blood-brain barrier--targets periphery.

 

 

Term
Physostigmine
Definition

Reversible AChE Inhibitor

 

Used to treat Glaucoma--Causes Miosis and opening of Canal of Schlemm via Iris Muscarinic Receptors

 

Tertiary Amine--Not Charged, Enters Brain

Term
DFP
Definition

Type of Organophosphate

Irreversible Inhibition of AChE

 

Inhibits by the ester remaining tightly bound to AChE-->must form new enzyme to regain function


Used in treatment of Glaucoma--last resort b/c they cause cataracts.

Term
Pralidoxime
Definition

Antidote to Organophosphate AChE Inhibition

Used along with Atropine to block muscarinic effects and ventilation

 

Can remove ester from active site.

 

Does not act on CNS

Term
Atropine
Definition

Muscarinic Receptor Antagonist

 

In eye-->Dilation (not for glaucoma bc it increases pressure)

In GI-->Reduces secretions and motility

Decreases sweating

 

Side Effects--> Tachycardia (negligible on BP)

 

Used to treat Cholinergic Crisis

Term
Scopolamine
Definition

Muscarinic Antagonist from BellaDonna Plant

 

More CNS activity than Atropine-->Drowsiness and Amnesia

 

 

 

Term
Motion Sickness Drug
Definition

Scopolamine


Inhibits Muscarinic Receptors of Vestibular System when used transdermally

Term
Ipratropium
Definition

Muscarinic Antagonist

 

Inhaled to treat asthma and other airway disease which has a strong parasympathetic component.  Causes Bronchodilation

 

Quaternary Amine--Does not cross blood-brain barrier

Term
Parkinson's Disease and Muscarinic Antagonists
Definition
Because dopamine transmission is low, balancing with low ACh transmission is helpful with other therapy
Term
Nicotine
Definition

Depolarizing (Non-competitive) Cholinergic Blocker

 

Causes Initial Transient Stimulation, followed be persistant depression. 

At NMJ--causes paralysis via depolarization blockade

Sensory receptors--stimulates pain receptors, chemoreceptors at carotid body, and various mechanostretch receptors


CNS--At low doses (smoking)-->Alerting Effect

At moderate doses-->Tremors and Vomitting and Diarrhea

At high doses-->convulsions, coma and death via respiratory arrest.

Term
Trimethaphan
Definition

Non-depolarizing (Competitive) Ganglionic Blocker

 

Competes with ACh for the nicotinic receptor at Ganglion


You block whatever system provides primary autonomic tone.


Eg.  Sympathetic for arterioles-->results in vasodilation

Parasympathetic for iris-->Dialation

Term
D-tubocurarine
Definition

Competitive (non-depolarizing) Neuromuscular Blocking Agent

 

Blocks ACh at motor end plate.

 

Paralyzes skeletal muscle (1st eye, jaw, swallowing, peripheral muscles, abdominal and intercostal muscles, and finally diaphragm)

 

Causes Histamine Release

 

Enhanced by anesthetics

Antagonized by neostigmine and edrophonium

 

 

Term
Atracurium, Vecuronium and Mivacurium
Definition

Competitive (Non-depolarizing) Neuromuscular Blocking Drug

 

Shorter acting than D-Tubocurarine (35-45 min)


D-tubocurarine>atracurium>vecuronium (25-40min) > Mivacurium (15 min)

 

Can be antagonized by edrophonium or neostigmine

 

Term
Succinylcholine
Definition

Depolarizing Neuromuscular Blocker

 

Produces Persistent Depolarization of Motor End Plate

Rapid and Brief (initial twitching followed by ~5 minutes of paralysis)

 

Metabolized by pseudo-ChE...some patients do not form this enzyme and have higher risk of side effects

 

CANNOT BE ANTAGONIZED

 

Term

Contraindications to Cholinimimetics

1. Asthma

2. Peptic Ulcer

3.Coronary Insufficiency

4.Hyperthyroidism (causes atrial fibrillation)

 

Definition
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