Pharm for Hypersensitivity Reactions

Question 1

What are the two categories of drugs for allergic rhinitis

Answer 1

1) Preventers: used for prophylaxis

2) Relievers: used for acute symptom relief

Question 2

What are types of preventers are there for Allergic Rhinitis

Answer 2

1) Antihistamines (ie diphenhydramine)

2) Intranasal corticosteroids (ie fluticasone)

3) Mast cell stabilizers/ trying to desensitize from releasing histamine (ie cromolyn)

4) Leukotriene Receptor Antagonists (Montelukast)

Question 3

What are types of relievers are used for Allergic Rhinitis

Answer 3

1) Decongestants: sympathomimetic agents given through oral and nasal routes (ie pseudoephedrine, oxymetazoline): mimic fight/flight SNS

2) Anticholinergics: allow for unopposed sympathomimetic activity to cause vasoconstriction (ipratropium): block PNS

Question 4

Pharmacotherapy Considerations for Allergic Rhinitis

Answer 4

Treatment will sometimes exceed symptom duration/resolution: want to get symptoms under-control to make sure that the allergic cells are as desensitized as much as possible

Often use “controllers” to stabilize allergy cells and desensitize and achieve control and then switch to a med that can maintain control.

Question 5

How do antihistamines work

Answer 5

H1 receptor sits on the mast cell: H1 receptor antagonists block histamine receptors associated with inflammation

Question 6

Where are H2 receptors located

Answer 6

In the stomach, produce more stomach acid

Question 7

What are the older antihistamines called

Answer 7

1st Generation

Newer is called 2nd generation

Question 8

When do you use antihistamines

Answer 8

allergic rhinitis, urticaria, minor allergies

adjunct theory for anaphylaxis

vertigo and motion sickness (we have histamine receptors in our ears)

Question 9

Mechanism of action for antihistamines (ie diphenhydramine/Benadryl)

Answer 9

First generation antihistamine

Antagonizes the H1 receptors, by competing with free histamine for receptor sites, preventing vasodilation associated with histamine

antagonizes M2 acetylcholine receptors

Question 10

What are adverse effects for antihistamines (ie diphenhydramine/Benadryl)

Answer 10

Unpredictable!
Sedation, difficulty concentrating/confusion

Ataxia (altered balance/movement)

Anticholinergic effects (CANT see, pee, spit, or shit)

Increase HR

Photophobia, blurred vision

Temporary erectile dysfunction

Results in light headiness, orthostatic instability, confusion, possible increased IOP (glaucoma)

Question 11

Who is most effected by anticholinergic effects

Answer 11

Older people

imbalance in our CNS, so we have more sensitivity in our muscarinic receptors and more acetylcholine

More sensitive in us triggering this imbalance

Increase in fall risk!

Question 12

Who do we need to be cautious with antihistamines

Answer 12

Heart or arrhythmia issues

Question 13

What conditions are Secondary Generation Cetirizine (Reaction)

Answer 13

Allergic rhinitis, anaphylaxis, allergic conjunctivitis

Question 14

Why do we tend to use Secondary Generation Antihistamines more now

Answer 14

favour H1 receptor and not the muscarinic receptors so we can get away from the anticholinergic receptors.

But there can be some minor anticholinergic effects.

Question 15

What is the mechanism of action for Secondary Generation Cetirizine (Reaction)

Answer 15

Competes with histamine for binding to H1 rector sites (same as first gen)

side effects = same or better

Question 16

What is fluticasone (Flonase) used for

Answer 16

Intranasal glucocorticoid

Seasonal and perennial allergic rhinitis

Question 17

What is the mechanism of action for fluticasone (Flonase)

Answer 17

Binds to glucocorticoid receptor, promoves anti-inflammatory effects

Inhibits histamine release by mast cells
Prevents macrophage accumulation
Reduces leukotriene release

Question 18

What are adverse effects for fluticasone (Flonase)

Answer 18

Very few when applied topically (little systemic absorption)
Local burning, bitter taste
Headache
Epistaxis

Question 19

Serious adverse effects for diphenhydramine

Answer 19

With high doses, prolonged OT interval on ECG that can lead to cardiac arrhythmias including tornadoes de pointes

Increased IOP (closed angle glaucoma)

Question 20

Serious adverse effects for fluticasone (Flonase)

Answer 20

Swallowing large amounts can cause systemic adverse effects associated with glucocorticoids

Question 21

Mode of action for mast cell stabilizers (Cromolyn)

Answer 21

Drugs that inhibit Ca+2 entry into mast cells, which reduces release of histamine and leukotrinenes from Mast cells.

Can take several days to start working.

Question 22

How are mast cell stabilizers (Cromolyn) taken

Answer 22

Poor BioAvail so eye drops or inhaled (nebules)

Question 23

What are the side effects for mast cell stabilizers (Cromolyn)

Answer 23

Very few with similar efficacy to antihistamines but delayed onset especially for sever symptoms

Question 24

Leukotriene Receptor Antagonists (Montelukast) mode of action

Answer 24

Blocks action of leukotriene D4 (LTD4), reducing inflammation and bronchoconstriction associated with LTD4

Also considered a antihistamine
Usually used as a controller type drug for asthma
Few adverse effects

Question 25

Types of decongestants for allergic rhinitis

Answer 25

1) Sympathomimetic agents

2) Intranasal route (ie Oxymetazoline)

3) Oral route (ie. pseudoephedrine)

Question 26

How do sympathomimetic agents work

Answer 26

Alpha receptor agonist -> cause vasoconstriction because if we step on the SNS in our periphery to get blood to our core

Promote constriction of nasal blood vessels

Increase HR,

Use in caution with those who have diabetes because there will be spikes in sugar

Question 27

How do intranasal decongestants (ie Oxymetazoline) work

Answer 27

Immediate relief, used for 3 to 5 days

Sudden discontinuation of drug can cause rebound congestion

Few adverse effects: dry nasal passage, rebound congestion

Question 28

How do oral route decongestants (ie pseudoephedrine)

Answer 28

Slower onset of action

Rebound congestion does not typically occur upon discontinuation

Risk for systemic adverse effects

Question 29

Pharmacology of Anaphylaxis

Answer 29

Managing symptoms of anaphylaxis and preventing further inflammation

Symptomatic relief provided by sympathetic agents such as epinephrine

Anti-inflammatory drugs include antihistamines and systemic glucocorticoids

Question 30

What is Epinephrine (Adrenaline) used for

Answer 30

Anaphylaxis

Hypotension

Dysrhymias (severe ventricular dysrhythmias, bradycardia, systole)

Severe Asthma

Question 31

Epinephrine (adrenaline) mode of action

Answer 31

Parenteral route

Non-specific adrenergic agonist with action at alpha1, beta1, and beta2 receptors which increases BP and opens airway

Question 32

Alpha1

Answer 32

vasoconstriction

Question 33

Beta1

Answer 33

Increased HR, force of contraction

Question 34

Beta2

Answer 34

Bronchodilation

Question 35

Adverse effects for Epinephrine (adrenaline)

Answer 35

Hypertension, dysrhythmias are a risk so careful monitoring is crucial

Sympathetic effects include: dry mouth, nausea, vomiting, palpitations, blurred vision, headaches

Extravasation of epinephrine into tissues can cause irritation, tenderness and even ischemia

Question 36

What is used when extravasation happens

Answer 36

Alpha antagonists such as prazosin