Unit 3 - Hypersensitivity Reactions 2

Question 1

What is the function of corticosteroids?

Answer 1

Anti-inflammatory medicines used to treat a range of conditions

• asthma and chronic obstructive pulmonary disease (COPD)
• hay fever
• hives and eczema

Question 2

Give an example of a corticosteroid that is used to treat asthma, hay fever and hives and eczema

Answer 2

Prednisone

• tablet
• inhaler

Question 3

What is anaphylaxis?

Answer 3

Systemic response to hypersensitivity

Question 4

When does anaphylaxis occur most frequently?

Answer 4

In the 4th decade of life

- particularly when the drug is given parentally

Question 5

What happens when the body goes into anaphylactic shock?

Answer 5

• blood pressure suddenly drops

- airways narrow - blocking normal breathing

Question 6

What are the symptoms of anaphylactic shock?

Answer 6

Skin reactions
- hives
- flushed skin
- paleness
Suddenly feeling too warm
Feeling like you have a lump in your throat or difficulty swallowing
Nausea, vomiting or diarrhoea
Abdominal pain
A weak and rapid pulse
Runny nose and sneezing
Swollen tongue and lips
Wheezing or difficulty breathing
Sense that something is wrong with your body
Tingling hands, feet, mouth or scalp
Struggling to breathe
Dizziness
Confusion
Sudden feeling of weakness
Loss of consciousness

Question 7

What are the three main types of adrenaline autoinjector?

Answer 7

EpiPen
Jext
Emerade

Question 8

What is hyposensitisation?

Answer 8

To inject repeatedly small quantities of allergen
Results in an increase in IgG against allergen
- corresponding fall in specific IgE against allergen

Question 9

What allergens can be used for hyposensitisation?

Answer 9

Pollinex - grass pollen

Pharmalgen - bee and wasp venom

Question 10

Which group of patients are not eligible for hyposensitisation treatment to grass pollen?

Answer 10

Asthmatic patients

- more likely to have a severe reaction

Question 11

Why are asthmatics included in hyposensitivity treatment for wasp and bee venom?

Answer 11

The sting is potentially life threatening, whereas hyposensitisation is under controlled conditions and resuscitation facilities are available

Question 12

Why should care be taken in hyposensitivity patients taking beta-adrenergic blocking agents (beta blockers) or angiotensin-converting enzyme (ACE) inhibitors?

Answer 12

Medication may mask early signs and symptoms of anaphylaxis and may make the treatment of anaphylaxis more difficult

• beta blockers amplify the adrenaline reaction
• ACE inhibitors - risk of severe anaphylactoid reactions
• angioedema occurs in 0.1% to 0.2% of patients (accumulation of bradykinin)

Question 13

Which is clinically the most important drug allergy?

Answer 13

Penicillin allergy

- greater than 1% of all adverse reactions still associated with Penicillins

Question 14

What is the most common cause of anaphylaxis?

Answer 14

Penicillin allergy is the most common cause of fatal and non-fatal anaphylactic reactions.
Several studies suggest that up to 75% of fatal anaphylactic episodes are due to penicillin.

Question 15

What percentage of people have an allergic reaction after administration of penicillin?

Answer 15

About 0.2% of people treated with penicillin have a reaction upon 1st administration.
About 2% of those treated with penicillin will have a reaction upon 2nd administration

Question 16

What are the potential hypersensitivity reactions to penicillin?

Answer 16

Hypersensitivity reactions to penicillin:
Rash, diarrhea, nausea,urticaria - more common
Fever, erythema, dermatitis, angioedema, - infrequent

Erythemais redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation.
Dermatitisusually involves itchy, dry skin or a rash on swollen, reddened skin. Or it may cause the skin to blister, ooze, crust or flake off.
Angioedemais the rapid edema, or swelling, of the area beneath the skin or mucosa. It is normally an allergic reaction, but it can also be hereditary. The swelling happens because fluid accumulates.

0.01% of those treated experience serious adverse event – anaphylaxis.
Mostly occurring with parenteral administration. About 1 in 10 of these will die.

Skin - generalized hives, itchiness, flushing.
Swelling of the lips, tongue or throat.
Respiratory - shortness of breath, wheezes, low oxygen.
Heart & vascular - coronary artery spasm subsequent myocardial infarction or dysrhythmia.
Drop in blood pressure loss of consciousness, shock

Question 17

WHat other antibiotic has a higher risk of adverse reaction if the patient has a penicillin allergy

Answer 17

An approximate 2–fold greater chance of suffering an allergic reaction to cephalosporin antibiotics if one has a penicillin allergy.

Question 18

What are the different types of hypersensitivity reactions?

Answer 18

Type I: Immediate Hypersensitivity These allergic reactions (including anaphylactic reaction) are systemic or localized, as in allergic dermatitis (e.g., hives, wheal and erythema reactions) or allergic rhinitis (hay fever) - (Antibody-dependent: IgE)
Type II: Cytotoxic Reaction (Antibody-dependent: IgM, IgG) - Autoimmune
Type III: Immune Complex Reaction (Antibody-dependent: IgM, IgG)
Type IV: Cell-Mediated: Delayed Hypersensitivity (Cell-dependent)