Adrenergic Agonists

Question 1

Catecholamine Chemistry

Answer 1

catechol ring with -OH groups

non-catecholamine sympathomimetic drugs too

Question 2

Sympathomimetic Amines General MOAs

Answer 2

1) direct acting
2) indirect action
3) mixed action

Question 3

Direct Acting Sympathomimetic Amines MOA

Answer 3

= act directly on adrenoreceptors (GPCR)

• E, NE,
• Isoproterenol, Albuterol

Question 4

Indirect Acting Sympathomimetic Amines MOA

Answer 4

= act presynaptically to increase cats in synaptic cleft

1) Displace stored cats from adrenergic nerve (amphetamines and tyramine)
2) Inhibit reuptake through NE transporter (NET) (cocaine and Tricyclic antidepressants)
3) Prevent enzymatic metabolism of NE (monoamine oxidase, catechol-O-methyltransferase inhibitors)

Question 5

Mixed Acting Sympathomimetic Amines MOA

Answer 5

= act on adrenoreceptros and release cats
Ephedrine (nasal decongestant) - prolonged stimulant action
Pseudoephedrine - weaker stimulant…homemade meth!

Question 6

Alpha 1 Adrenoceptor Distribution and Activity

Answer 6

*Vascular smooth muscle contraction
Pupillary dilator muscle contraction
Liver glycogenolysis
Prostate contration
*Gq -> phospholipase C -> DAG -> IP3 -> ACTIVATE Protein Kinase C and PKC

Question 7

Beta Adrenoceptor Activity

Answer 7

*Gs -> ACTIVATE Adenylyl Cyclase
B1: heart, inc force and rate
B2: lungs, uterine, vessels, smooth muscle relaxation
B3: fat cells, activate lipolysis

Question 8

Alpha 2 Adrenoceptor Activity

Answer 8

Postsynaptic CNS 
Adrenergic & cholinergic NT inhibit release 
Vascular smooth muscle contraction
Fat cells (lipolysis inhibition) 
Platelet aggregation 
*Gi -> INHIBIT Adenylyl Cyclase

Question 9

Activation of Alpha 1 Adrenoceptors

Answer 9

• Vasoconstriction
• Nasal decongestion
• Mydriasis (dilation of the pupil)
• Hypertension
• Intestinal relaxation

Question 10

Activation of Beta Adrenoceptors

Answer 10

• Vasodilatation
• Bronchial relaxation
• Intestinal relaxation
• Stimulation of heart muscle contractions
• Increase in heart rate

Question 11

Alpha-1 Selective Agonists

Answer 11

Phenylephrine

Methoxamine

Question 12

Alpha-2 Selective Agonist

Answer 12

Gi= INHIBITION of AC 
Clonidine- antihypertensive, anti-tachycardia 
Methyldopa
Guanfacine
Guanabenz

Question 13

Beta Agonists

Answer 13

Isoprotorenol (none selective)
B1: Dobutamine (cardioselective)
B2: Albuterol, Terbutaline
B3: cause lipolysis (under devo)

Question 14

Amphetamines MOA

Answer 14

Amphetamines bind to and REVERSE the Norepinephrine Transporter, leading to an increase in NE in the synapse.
-CNS stimulant - enhances alertness, appetite depressant

Question 15

Amphetamine-Like Drugs

Answer 15

• Methylphenidate (Ritalin) - ADHD, enhanced alertness and focus
• Adderall- amphetamine isomers, ADHD and cognitive enhancement
• Modafinil- Not an amphetamine. Used in narcolepsy with fewer side-effects than amphetamine

Question 16

Tyramine

Answer 16

MAOIs block tyramine metabolism-> too much tyramine => high BP, sweating, nausea, vomiting & dilated pupils
***Patients taking MAOIs should avoid tyramine-containing foods such as cheese

Question 17

Catecholamine Reuptake Inhibitors (Antidepressants with cardiovascular effects)

Answer 17

Imipramine- orthostatic hypotension
Atomoxetine- increase blood pressure
Duloxetine- no cardio effects

Question 18

Dobutamine

Answer 18

B1 selective beta agonist to increase contractility and CO

cardiogenic shock from MI

Question 19

Albuterol, Terbutaline

Answer 19

B2 selective beta agonist to enhance bronchodilation. (asthma flare)

Question 20

Isoprotorenol

Answer 20

NON-selective beta agonist