Pharmacology Exam 3

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Types of Adrenergic receptors
- alpha 1
- alpha 2
- beta
Targets of Norepinephrine
- mono-amine oxidase
- COMT
- post synaptic membrane
Alpha 1 Adrenergic receptor signaling
- GPCR reactions
- smooth muscle contraction
Alpha 2 adrenergic signaling
- GPCR
- inhibition of transmitter release
- smooth muscle contraction
Beta adrenergic receptor signaling
- heart muscle contration
- smooth muscle relaxation
- glycogenolysis
Roles of alpha 1 receptors
- most vascular smooth muscle
- pupillary dialator muscle
- pilomotor smooth muscle contraction
- prostate contraction
- heart contraction
Role of alpha 2 receptors
- platelet aggregation
- inhibition of neurotransmitters at adr/chol nerve terminals
- some vascular smooth muscle contraction
- inhibition of lipolysis
- inhibition of insulin release
Role of B1 receptors
- heart muscle contraction
- renin secretion
- ghrelin secretion
Role of B2 receptor
- smooth muscle relaxation
- lipolysis
- renin secretion
- dialate arteries
- relaxation of non-pregnant uterus
B3 role

lipolysis
increase in number of carbons on the amino terminus

increase B (especially B2) selectivity
Addition of OH group on substrates
- increases potency (faster metabolism by COMT)
- decreases bioavailability
Alpha 1 agonsits
- phenylephrine
- pupil dilation
- increased BP
Alpha 2 agonists
- clonidine
- treatment of hypertension
- neuropathy
- sleep disorders
B agonsists
- Dobutamine
- - heart failure
- Terbutaline
- - delay premature labor
What is the common funciton of all types of adrenergic receptors?

Muscle contraction
Phenylephrine

potent alpha 1 agonist
administration of phenylephrine
- parenteral
- oral
- local
uses of phenylephrine
- dilate pupil
- nasal decongestant
Norepinephrine

potent alpha and beta1 receptor agonist
Administration of NE

parenteral
Uses of NE
- Used as a pressor
- (constricts arteriols to increase BP)
Epinephrine

potent alpha, B1 and B2 agonist
administration of epinephrine

parenteral
uses of epinephrine
- anaphylaxis
- glaucoma
- in combination with local anesthetics
Isoproterenol
- non-selective B agonist
- bronchodilation
- increased cardiac output
administration of isoproterenol
- oral
- parenteral
- local (inhaled)
Uses of isoproterenol
- asthma
- COPD
- cardiostimulant
Which of the following adrenergic agonists are selective to alpha adrenergic receptors?

phenylephrine
competitive antagonist

EC50 decreased but efficacy not changed
Irreversible antagonist

decrease in efficacy because receptor is destroyed
Yohimbine
- alpha 2 selective antagonist
- aphrodisiac
potential uses of yohimbine
- male impotence
- depression
- obesity
- non-insulin dependant DM
- same side effects as antidepressants
Yohimbine is metabolized by

CYP3A4 and 2D6
ADR of yohimbine
- narrow therapeutic window
- anxiety
- high BP
- rapid HR
- hallucination
- seizure
- renal failure
prazosin decreases the effects of epinephrine mediated action of adrenergic receptors by:

decreasing potency of epinephrine
Phenoxybenzamine (Dibenzyline)
- Irreversible antagonist of a1 > a2
- higher effect when sympathetic tone is high (upright)
- metabolized by 3A4
Uses of phenoxybenzamine
- last resort for uncontrolled BP
- pheochromocytoma
- low bioavailability
Adverse reactions with phenoxybenzamine
- postural hypotention
- reflex tachycardia
- CNS issues
- Ejaculation inhibition
- Nasal congestion
- Miosis (pupil constriction)
Phentolamine (Regitine)
- competitive blocker of a1 and a2
- medium bioavailability
uses for phentoalmine
- extravasation of NE or DA
- emergency hypertention (cocain or pheochromocytoma)
- shock
- pulmonary edema
- ED
- regional pain syndrome
ADR of phentolamine
- Cardiac and CNS related
- tachycardia
- arrhythmias
- mycocardial ischemia
Prazosin (minipres)
- alpha 1 selective antagonist
- low bioavailabilty due to p-gp efflux
- CYP3A4
uses of prazosin
- hypertension
- BPH
- scorpion stings
- severe nightmares in children
ADR of prazosin
- orthostatic hypotension
- loss of consiusness (syncope)
- nasal congestion
- priapism
Tamsulosin
- alpha 1a selective blocker (prostate)
- BPH treatment
- ADR: retrograde ejaculation
- high bioavailability
- CYP3A4 and 2D6
What is the last resort for uncontrolled BP?

C. Phenoxybenzamine
uses of beta blockers in heart issues
- coronary artery disease
- hypertension/arrhythmia
- CHF
- cardiomyopathy
uses of beta blockers other than the heart
- pheochromocytoma
- hyperthyroidism
- migraine
- tremor
- anxiety
- glaucoma
properties of beta blockers
- L-isomer is more potent
- B1 (cardiovascular) selectivity
- partial agonist activity
Pharmacokinetics of B-blockers
- lipid soluble (high bioavailablity)
- metabolized in liver
- enter the CNS
- shorter elimination half lives (fast abs.)
Adverse reactions to beta blockers
- cardiac
- decresed vascular perfusion
- bronchoconstriction
- diabetes mellitus
- depression, nightmares
- withdrawl
Optimal clearance time to decrease ADR of beta blockers

3-4 hours
Pindolol

easily absorbed but not easily metabolized
B-Blockers that have B1=B2 selectivity
- propranolol
- pindolol
B-Blockers with B1>B2 selectivity
- metoprolol
- esmolol
Propranolol uses
- cardiovascular
- migrane
- post traumatic stress
- glaucoma
Inhibitors of CYP3A4 and CYP2D6
- clonidine
- quinidine
- cimetidine
Induceers of CYP3A4 and 2D6
- Phenobarbital
- Rifampicin
Propranolol given with inhibior would:

increase efficacy
Propranolol given with an inducer would:

increase efficacy
Metoprolol

many more side effects
serious side effects of metoprolol
- very slow HR
- cyanosis/tingling of extremities
- hair loss
- sexual dysfunction
- mood change
- trouble breathing/cough

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Rx2013

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Pharmacology Exam 3

Description

Adrenergic Agonist/Antagonists

Updated

2010-10-20T19:31:14Z

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