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Adrenergic Pharmacology
All the need to know drugs for the adrenergic receptors
65
Biology
Graduate
10/26/2010

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Term
What are the sympathomimetic catecholamines?
Definition

1.  epinephrine (generic; Adrenaline)

2.  Norepinephrine (generic; Levophed)

3.  Isoproterenol (generic; Isuprel)

4.  Dopamine (Dopar; Larodopa)

Term
What are the non-catecholamine sympathomimetics that are alpha agonists?
Definition

1.  Tyramine

2.  Amphetamine (generic)

3.  Methamphetamine (Desoxyn)

4.  Methylphenidate (generic; Ritalin)

5.  Ephedrine (generic)

6.  Phenylephrine (generic; Neo-synephrine)

7.  Methoxamine (Vasoxyl)

Term
What are the non-catecholamine sympathomimetics that are beta agonists?
Definition

1.  Metaproterenol (Alupent; generic)

2.  Terbutaline (Brethine; Bricanyl)

3.  Albuterol (generic; Proventil; Ventolin; others)

4.  Salmeterol (serevent)

5.  Ritodrine (generic)

6.  Dobutamine (generic; Dobutrex)

Term
What are the sympathomimetic inhibitors of reuptake?
Definition

1.  cocaine

2.  Tricyclic antidepressants

Term
What are the blockers of adrenergic nerve function?
Definition

1.  clinidine (generic; Catapres)

2.  alpha-methyl DOPA (generic)

3.  alpha-methyl-para-tyrosine

4.  Reserpine (generic)

5.  Guanethidine (Ismelin)

Term
What are the CNS acting sympatho-inhibitory agents?
Definition

1.  clonidine (generic; Catapres)

2.  alpha-methyl DOPA (generic)

Term
What is the Tyrosine hdroxylase inhibitor?
Definition
alpha-methyl-para-tyrosine
Term
What are the blockers of adrenergic nerve function that cause catecholamine depletion?
Definition

1.  reserpine (generic)

2.  Guanethidine (ismelin)

Term
What are the alpha-adrenoreceptor blockers (antagonists)?
Definition

1.  phentolamine

2.  phenoxybenzamine

3.  prazosin

4.  doxazosin

5.  terazosin

6.  yohimbine

Term
What are the beta-adrenoceptor blockers (antagonists)?
Definition

1.  propranolol (generic; Inderal)

2.  Metoprolol (generic; Lopressor)

3.  Atenolol (generic; Tenormin)

4.  Pindolol (generic; Visken)

5.  Timolol (generic; Blocadren)

6.  Nadolol (generic; Corgard)

7.  Betaxolol (Kerlone)

8.  Esmolol (BreviBloc)

Term
What are some drugs that are both alpha and beta adrenoreceptor antagonists?
Definition

1.  Labetalol (generic; Normodyne; Trandate)

2.  Carvedilol (Cartrol)

Term
Where are alpha 1 receptors located in the body?
Definition
They are located postjunctionally at most sympathetic neuroeffector synapses (except the heart and juxtaglomerular cells of the kidney).  These are usually excitatory (increased bp, pupil dilation, piloerection, viscous salivation, contraction of GI and urinary sphincters) although a few systems are inhibited (GI and urinary smooth muscle)
Term
Where are the alpha 2 receptors in the body?
Definition
They are found on the postjunctional membranes of many autonomic end organs and act like alpha 1 receptors.  However, they are also found on the prejunctional membrane where they act as a NEGATIVE FEEDBACK MECHANISM to prevent excessive release of NE. 
Term
Where are the Beta 1 adrenoceptors in the body?
Definition
They are in the heart and the juxtaglomerular apparatus of the kidney.  They are potently stimulated by NE and are responsible for increasing heart rate, conduction and contractile force as well as neural release of renin from JG cells.  They are also the only innervated Beta-adrenoceptors. 
Term
Where are the Beta 2 adrenoceptors in the body?
Definition
vasculature.  They cause vascular vasodilation and consequent reduction of blood pressure, relaxation of bronchial smooth muscle, inhibition of GI and urinary tract smooth muscle, and relaxation of gravid uterus. 
Term

epinephrine

1.  Type

2.  Where it comes from?

3.  What receptors does it act on?

4.  How is it administered?

Definition

1.  Catecholamine

 

2.  chromaffin cells of the adrenal medulla (not from peripheral nerve endings).  It is also released in the CNS as a neurotransmitter.

 

3.  acts on all alpha and beta adrenoceptors. 

 

4.  parenterally or by inhalation

Term

norepinephrine

1.  Type

2.  Which receptors does it act on?

 

Definition

1.  catecholamine

2.  all alpha adrenoceptors as well as beta 1 adrenoceptors

Term

Isoproterenol

1.  Type

2.  Which receptors does it act on?

3.  Uses

Definition

1.  Synthetic catecholamine

2.  pure beta-adrenergic stimulant

3.  relieve bronchoconstrictive states with the cardiovascular effects usually being untoward side effects.

Term

dopamine

1.  Type

2.  Where does this act?

3.  Uses

 

Definition

1.  Catecholamine

2.  acts in the CNS (important in the xtrapyramidal motor system).  Renal blood vessels possess non-innervated dopamine receptors that produce vasodilation in the kidney

3.  deficiency causes Parkinson's disease, so we administer L-DOPA for treatment.

Term

tyramine

1.  Type

2.  Effects on the body

Definition

1.  Non-catecholamine sympathomimetic (alpha adrenoceptor agonists)

 

2.  Causes a massive release of NE from sympathetic nerve endings.  This may cause hypertensive crisis in patients who are taking an MAO inhibitor to treat depression (MAO inactivates tyramine)

 

With a massive release of NE, this can cause an increase in blood pressure.

Term

amphetamine

1.  Type

2.  Uses

3.  Side Effects

Definition

1.  non-catecholamine sympathomimetic (alpha-adrenoceptor agonist)

 

2.  Orally effective and readily enters the CNS.  Temporary elevation of mood and appetite suppression.

 

3.  Highly toxic and lethal.  Due to tolerance, the ED50 increases, but the LD50 remains unchanged.  If they die, the major find at autopsy is cerebral hemorrhage that may be secondary to intense vasoconstriction of CNS blood vessels

 

Note:  indicated in treatment of hyperkinetic children or narcolepsy.

Term

methamphetamine

1.  Type

2.  Uses

3.  Side Effects

Definition

1.  non-catecholamine sympathomimetic (alpha-adrenoceptor agonist)

 

2.  Orally effective and readily enters the CNS.  Temporary elevation of mood and appetite suppression.

 

3.  Highly toxic and lethal.  Due to tolerance, the ED50 increases, but the LD50 remains unchanged.  If they die, the major find at autopsy is cerebral hemorrhage that may be secondary to intense vasoconstriction of CNS blood vessels

Term

methylphenidate

1.  Type

2.  Uses

3.  Side Effects

Definition

1.  non-catecholamine sympathomimetics (alpha-adrenoceptor agonist)

 

2.  CNS stimulant.  This is Ritalin and is used in the treatment of children with ADHD.

 

3.  CNS excitation and convulsions

Term

ephedrine

1.  Type

2.  Uses

3.  Side Effects

4.  Which receptors does it act on?

Definition

1.  non-catecholinamine sympathomimetics (alpha adrenoceptor agonist)

 

2. Oral treatment for bronchial asthma (Beta effect) and is found in over-the-counter medications for ear and nasal decongestion.  It has also been used for its alpha effects as a pressor agent.  Also, in ophthalmology to produce short lasting mydriasis without cycloplegia.

 

3. Didn't list any but I'm sure you can think of something

 

4.  acts as an agonist to all alpha and beta receptors in the body

Term

Phenylephrine (Neo-synephrine)

1.  Type

2.  Uses

3.  Side Effects

Definition

1.  non-catecholamine sympathomimetic (alpha adrenoceptor agonist)

 

2.  orally effect in extremely large doses but it is in some over-the-counter cold medications (questionable).  it is a pressor agent and is used to produce mydriasis in ophthalmology.  Used in nasal spray to produce local vasoconstriction in nasal airways (like Afrin with rebound)

Term

Methoxamine

1.  Type

2.  Uses

 

Definition

1.  non-catecholamine sympathomimetic (alpha-adrenoceptor agonist)

 

2.  administered parenterally as a pressor drug; used to produce mydriasis and sometimes to treat paroxysmal atrial tachycardia (via production of reflex bradycardia)

Term

Metaproterenol

1.  Type

2.  Which receptor does it target?

3.  Uses

4.  Side Effects

Definition

1.  non-catecholamine sympathomimetic (beta-adrenoceptor agonist)

 

2.  selective for beta 2 adrenoceptors

 

3.  Used to treat bronchial asthma.  It can be administered by inhalation or orally. 

 

4.  Cardiac side effects may be seen as they have some beta 1 adrenoceptor stimulating activity.

Term

Terbutaline

1.  Type

2.  Uses

3.  Side effects

Definition

1.  Non-catecholamine sympathomimetic (beta-adrenoceptor agonist)

 

2.  Used to prevent premature child birth

 

3.  It is a modification of metaproterenol but is longer lasting and has higher incidence of cardiac side effects.

Term

Albuterol

1.  Type

2.  Uses

Definition

1.  Non-catecholamine sympathomimetic (beta-adrenoceptor agonist)

 

2.  asthma treatment (similar to terbutaline).  It is long acting with fewer cardiac effects than terbutaline.

Term

Ritodrine

1.  Type

2.  Uses

3.  Side Effects

Definition

1.  beta-adrenoceptor agonist (selective for beta 2)

 

2.  use to relax smooth muscle of uterus and delay premature labor. 

 

3.  possible cardiac side effects

Term

Dobutamine

1.  Type

2.  Uses

3.  Side effects

Definition

1.  Beta-adrenoceptor agonist (selective for Beta 1)

 

2.  Increases cardiac output without vasoconstriction.  It increases the force of contraction with much less effort on heart rate and conduction.

 

3.  It is rapidly metabolized by the liver, thus it must be given IV under close supervision.

Term

Cocaine

1.  Type

2.  Uses

Definition

1.  Indirectly acting sympathomimetics

2.  Sometimes used for severe depression.  They block NE reuptake as their primary mode of action.  This is often used as a local anesthetic.

Term

Tricyclic antidepressants

1.  Type

2.  Uses

Definition

1.  Potent inhibitor of catecholamine reuptake in adrenergic nerve terminals

 

2.  Used for their CNS effects in treating pathological depression

Term

Guanethidine (ismelin)

1.  Type

2.  Uses

Definition

1.  Blocker of adrenergic nerve function (catecholamine depletion in the peripheral sympathetic nerve endings).  It does this by preventing the nerve action potential from invading the fine nerve terminals so that NE is not released (blocker of action potentials).  It can also displace the stored NT.

 

2.  potent antihypertensive drug.  It does not pass the blood-brain barrier so it cannot get into the CNS.

 

 

Term

6-OH dopamine

1.  Type

2.  Uses

Definition

1. cytodestructor of nerve terminals

 

2.  experimental; pumped into sympathetic neurons and it destroys nerve terminals.

Term

Clonidine

1.  Type

2.  Uses

3.  Side effects

Definition

1.  CNS acting sympatho-inhibitory agent on alpha 2 receptor

 

2.  antihypertensive drug; readily penetrates into CNS where it acts to decrease sympathetic tone to the blood vessels and to the heart.  It may also act in the CNS to enhance vagal outflow to the heart by potentiating baroreceptor mechanisms.  Also used in withdrawal treatment from opioid and ethanol addiction. 

Term

alpha-methyl DOPA

1.  Type

2.  Uses

Definition

1.  CNS acting sympatho-inhibitory agent

 

2.  antihypertensive agent; crosses the blood brain barrier and in the CNS is converted to alpha-methyldopamine and then to alpha-methylnorepinephrine that is a potent alpha 2 adrenoceptor agonist.

Term

alpha-methyl-para-tyrosine

1.  Type

2.  Uses

Definition

1.  this is a tyrosine hydroxylase inhibitor (decreases the amt of NE)

 

2.  reduces transmitter concentration in sympathetic post-ganglionic fibers.  It is occassionally used to depress catecholamine levels in patients with a pheochromocytoma prior to surgery

Term

Reserpine

1.  Type

2.  Uses

3.  side effects

 

Definition

1.  catecholamine depletion.  interrupts the vesicular storage mechanism in sympathetic nerves. 

 

2.antihypertensive drug

 

3.  Will enter CNS and deplete all monoaminergic NT (NE, EPI, dopamine, serotonin); sedation; Parkinson's like syndrome

Term

Phentolamine

1.  Type

2.  Uses

3.  side effects

Definition

1.  alpha antagonist (prefers the alpha 1 receptor)

 

2.  In the past, used for screening test for pheochromocytoma for pts with high plasma levels of catecholamines (alpha antagonist is better therapy than beta agonist or something like that)

 

3.  releases histamine that produces many false positive rxns.

Term

Phenoxybenzamine

1.  Type

2.  How does it work?

Definition

1.  alpha-adrenoceptor agonist (preference for alpha 1 receptor)

 

2.  At first it is a competitive antagonist, but it also has the capcity to irreversibly bind to receptors because he is a beta-haloalkylamine

Term

Prazosin

1.  Type

2.  Uses

3.  Side Effect

Definition

1.  Alpha-adrenoceptor antagonist (especially alpha 1 receptors)

 

2. Treatment of hypertensive pts.

 

3.  Does not produce large reflex tachycardia seen with other alpha-adrenoceptor antagonists.  Some pts have extreme hypotensive effect and loss of consciousness during first dose.

 

Note:  It may act in the CNS to depress sympathetic tone and cardiovascular reflex mechanism.  This is why we may not see the strong reflex tachycardia.

Term

Terazosin and Doxazosin

1.  Type

2.  Uses

Definition

1.  Alpha-adrenoceptor antagonist

 

2.  prazosin-like drugs with longer half life which permits once a day dosing. Used to treat symptoms of benign prostatic hypertrophy

Term

Yohimbine

1.  Type

2.  Uses

Definition

1.  alpha-adrenoceptor antagonist (selective for alpha 2)

 

2.  Used in experimental studies in pts with spinal cord damage.  Prevents CNS hypotensive effects of clonidine and alpha-methyldopa.

Term

Propranolol

1.  Type

2.  Uses

Definition

1.  Beta-adrenoceptor antagonist (both beta 1 and beta 2)

 

2.  cardiac arrhythmias, potent local anesthetic, antihypertensive drug

 

Note:  metabolized by liver and elimination is through hepatic metabolism

Term

Metoprolol

1.  Type

2.  Uses

3.  side effects

Definition

1.  Beta-adrenoceptor antagonist (selective for beta 1)

 

2.  reduces plasma renin

 

3.  less local anesthetic effects than propranolol but produces more CNS side effects including fatigue, dizziness, headache, and insomnia

 

Note:  eliminated in liver

Term

Atenolol

1.  Type

2.  Uses

3.  side effects

Definition

1.  beta-adrenoceptor antagonist (selective for beta 1)

 

2.  usual beta 1 things.  Has a longer half life than metoprolol.

 

3.  Less CNS side effects than with metoprolol.  Can cause kidney problems because it is excreted in kidney.  Do not give to patients with severe renal disease

Term

Pindolol

1.  Type

2.  Uses

Definition

1.  beta-adrenoceptor antagonist

 

2.  it has intrinsic sympathomimetic activity which means that it also stimulates the beta 1 adrenoceptors.  Therefore, it produces less cardiac depression and is better tolerated during exercise

Term

Timolol

1.  Type

2.  Uses

Definition

1.  Beta-adrenoceptor antagonist

 

2.  Topical application produces a dramatic decrease in intraocular pressure.  This has become the drug of choice in treatment of open angle glaucoma.  Also clinically shown to be effective in preventing reinfarction of the myocardium.

Term

Nadolol

1.  Type

2.  Elimination

Definition

1.  Beta-adrenoceptor antagonist

 

2.  excreted primarily by the kidney and has a long duration of action

 

Term

Betaxolol

1.  Type

2.  Elimination

Definition

1.  beta-adrenoceptor antagonist (selective for Beta 1)

 

2.  metabolized by the liver but still has a long half life

Term

Esmolol

1.  Type

2.  Uses

3.  Metabolism

Definition

1.  beta-adrenoceptor antagonist (selective for beta 1)

 

2.  acute emergency control of ventricular heart rate in patients with atrial fibrillation or atrial flutter (particularly those arrhythmias resulting from intraoperative anesthesia)

 

3.  Ultrashort half-life is due to rapid hydrolysis of cytosolic red blood cell esterases

Term

Labetalol

1.  Type

2.  Uses

Definition

1.  alpha and beta antagonist (non-selective beta antagonist and alpha 1 antagonist)

 

2.  decreases plasma renin.  It is an effective antihypertensive agent that decreases total peripheral resistance with little reflex effect on the heart rate or cardiac output.  postural (orthostatic) hypotension is a problem in some pts.

Term

Carvedilol

1.  Type

2.  Uses

Definition

1.  beta and alpha andrenoceptor antagonist

 

2.  free radical scavenger that may protect heart cells from damage.  Treats patients with congestive heart failure.

Term
For what types of things could you use a sympathomimetic for the adrenergic things?
Definition
hemostasis, nasal decongestion, use with anesthetics, hyper and hypotension, anesthesia, cardiac stimulation, bronchodilation, ophthalmological exam, allergic reaction, appetite control, narcolepsy, behavioral disorders, parkinsonism, uterine motility, opioid withdrawal
Term
For what types of things could adrenergic blockers be used for?
Definition
hypertension, glaucoma, angina, post-infarction prophylaxis, congestive heart failure, migraine, stage fright, cardiac arrhythmias, essential tumor, pheochromocytoma, autonomic hypperreflxia, raynaud's, benign prostatic hypertrophy, hyperthyroidism
Term
What is the pathway for the synthesis of catecholamines?
Definition

1.  Tyrosine (tyrosine hydroxylase)

2.  DOPA (DOPA decarboxylase)

3.  Dopamine (Dopamine beta-hydroxylase)

4.  Norepinephrine (phenylethanolamine N-methyltransferase)

5.  Epinephrine (this last step doesn't occur at the nerve endings)

 

Note:  The enzymes that are in paratheses tell us what enzyme take that molecule to the next step.  For example, tyrosine hydroxylase converts tyrosine to DOPA.

Term
How is the synthesis of NE and EPI "controlled"?
Definition
Through a negative feedback system.  NE and EPI act on tyrosine hydroxylase to inhibit further hydroxylation of tyrosine.  This is the rate limiting step in sympathetic nerve terminals and for epinephrine in the adrenal gland.
Term
What is the mechanism of Uptake I?
Definition
This is when NE is taken up by the presynaptic nerve terminal to be recycled.  If it is not taken up in a storage vesicle, it will be inactivated by monozmine oxidase that is an intracellular enzyme associated with the mitochondria. 
Term
What is the mechanism of Uptake II?
Definition
This is when NE enters the postsynaptic cell and is enzymatically inactivated by the extra-neuronal enzyme, catechol-O-methyltransferase (COMT). 
Term
What is the primary CNS metabolite of dopamine and EPI?
Definition

phenyl glycol

 

MAO is used to get it there.

Term
What effects will you have on vasodilation/vasoconstriction if you add epinephrine?
Definition

low dose = decrease in blood pressure due to vasodilation.  This is because beta2 adrenoceptors are fewer in number but more sensitive than alpha adrenoceptors. 

 

high dose = increase in blood pressure due to vasoconstriction and vasoresponse.  This is because alpha adrenoceptors are more numerous but not as sensitive as beta 2 receptors.

Term
What are the effects of epinephrine on the body?
Definition

Epinephrine acts via beta-adrenoceptor mechanisms to increase adenylate cyclase activity to form the second messenger cAMP that has the following metabolic effects:

1.  increases plasma glucose by breakdown of liver glycogen

2.  inhibits synthesis of glycogen

3.  stimulates gluconeogenesis

4.  breaks down fat (triglycerides) to fatty acids

Term

salmeterol

1.  type

2.  uses

Definition

1.  beta adrenoceptor agonist

 

2.  treat bronchial asthma

Term

What are the catecholamine reuptake inhibitors?

What are their major implications?

Definition

Cocaine and Tricyclic Antidepressants are the reuptake inhibitors. 

 

These inhibitors can be a problem if you administer them with other drugs that need to get into the nerve terminal to act.  If you block the channel, you can't get NE or any of the other drugs in.  Some of those drugs are:

 

1.  tyramine

2.  guanethidine

3.  6-OH dopamine

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