Sympathomimetics

Question 1

What are medical uses of sympathomimetics?

Answer 1

Bronchodilation
Nasal decongestion
Relieve acute hypersensitivity reactions
Raise BP
Relieve adrenergic insufficiency
Stimulate heart

Question 2

Sympathomimetics as bronchodilators

Answer 2

B2 stimulants used to relieve bronchoconstriction in COPD

Receptors involved

• -B2
• -alpha 1
• -B1 action
  
  • –side effect

Question 3

Sympathetic bronchodilators can be used to ..

Answer 3

diagnose the cause of airway constriction

may be due to inflammation or bronchiolar spasm
B2 stimulants act in seconds

Question 4

Which adrenergic receptors does epinephrine work on?

Answer 4

alpha 1
beta 1
beta 2

Question 5

Which adrenergic receptors does albuterol work on?

Answer 5

beta 2

Question 6

Which adrenergic receptors does metaprotere nol work on?

Answer 6

beta 2

Question 7

Which adrenergic receptors does almeterol work on?

Answer 7

beta 2

Question 8

Aside from just bronchodilating, what do bronchodilators do?

Answer 8

Increase ciliary activity
Inhibit histamine and leukotriene release

(leukotrienes are powerful bronchoconstrictors)

Question 9

Why are Beta2 agonists drugs of choice?

Answer 9

• Most effective bronchodilators
• Tolerance with continued use overcome by increasing dose, usually
• Receptor down-regulation prevented or even partly reversed with corticosteroids

Question 10

What are precautions for using adrenergic bronchodilators?

Answer 10

• -“benign essential tremor” due to B2 stimulation
• -feelings of anxiety may limit use
• -increases blood sugar
  
  • -a1 and b2 receptors mobilize liver glycogen
• -dry pharyngeal membranes
  
  • -problem with epinephrine (vasoconstriction)

Question 11

Sympathomimetics as nasal decongestants

–MOA

Answer 11

alpha 1 agonists constrict dilated blood vessels and relieve nasal stuffiness and headache

Question 12

Examples of sympathomimetics used as nasal decogestants

Answer 12

Phenylephrine
–P.O. as nose drops or nasal spray

Pseudophedrine

• -Still “widely available”
• -CNS stimulant

Oxymetazoline
–Long duration

Question 13

Adverse reactions to nasal decongestants

Answer 13

Transient burning
Rebound congestion
Chemical rhinitis
CNS depression, hypotensio (imidazoline effect)

Question 14

Adrenergics in acute hypersensitivity

Answer 14

May involve foods, pollon, drugs, animals

B2 stimulants inhibit antigen-indcued histamine release

Epinephrine used

Question 15

Sympathomimetics are used in hypotension. Why is this important?

Answer 15

Necessity for “pressor” effect

• -below 40 mm Hg diastolic or 50 mm Hg systolic
  
  • –critical decrease in flow to heart, brain, and also gut, liver, kidney

Need to bring the pressure back up!

Question 16

What are some clinical situations in which there is a decrease in blood pressure?

Answer 16

General and spinal anesthesia
Drug overdose
Acute renal failure
Shock (sympathomimetics not used)

Question 17

What are two ways to increased blood pressure via drugs?

Answer 17

1. increase CO with beta1

2. increase peripheral resistance with alpha1

Question 18

Which drugs are used to increased BP via increase in peripheral resistance?

Answer 18

Norepinephrine
Alpha-1 stimulants - e.g. phenylephrine

These work on alpha 1

Question 19

Which drugs are used to increased BP via increase in CO?

Answer 19

Dopamine
Dobutamine

These work on beta1

Question 20

Short acting pressor agents are substrates for…

Answer 20

NET and ENT

Question 21

Long acting pressor agents are used for …

Answer 21

smoother pressure control

Question 22

Dopamine

Answer 22

Some b1

Dilation of renal, coronary, and mesenteric beds (D1 receptors)

Question 23

Dobutamine

Answer 23

B1, but little increase in HR

Question 24

Precautions in using “pressor” agents

Answer 24

1. Hyperthyroidism (excess receptors)

2. Necrosis on prolonged vasoconstriction (when used over a long time) – liver and kidney

Question 25

Disease states that show adrenergic deficiency

Answer 25

Pure Autonomic Failure (PAF) --disease of post ganglionic sympathetic nerves Postural Tachycardia Syndrome (POTS) Multiple System Atrophy (MSA) --autoimmune degeneration ANS centrally

Question 26

Adrenergics in sympathetic deficiency - what do they do? - which do we use?

Answer 26

Used to correct postural hypotension, urinary incontience, and retrograde ejaculation Midodrine - -alpha 1 agonist - -give early in the day to avoid nocturnal hypertension

Question 27

Sympathomimetics as cardiac stimulants - when? - which?

Answer 27

Use in AV block to prevent loss of consciousness - -"Stokes Adams" syndrome - -some pts alternate b/t 2nd and 3rd degree block - -definitive tx is pacements Use after bypass surgery IV epinephrine, isoproterenol, dobutamine, dopamine

Question 28

Indirect-acting sympathomimetics

Answer 28

- -Tyramine in some cheese, sausage - -Dopamine - -Pseudoephedrine, ephedrine Use NE uptake system, get into nerve end and cause some NE release