Unit 1. Lec 7-Antihistamines Flashcards
Define Allergy
Also known as atopy, is a disorder of the immune system resulting in excessive histamine release
When can allergic reactions occur? And what are some types?
Can occur to normally harmless environemental substances (allergens) like:
- Food allergens
- Drug allergens
- Venom (wasps, bees)
Common allergic reactions include:
- Eczema
- HIves
- Hay fever
- Asthma
What are the main categories of antihistamine drugs and what makes them different? and what is their mechanism of acton?
- First-generation antihistamine (CAN cross the BBB)
- Second-generation antihistamine (DO NOT cross the BBB)
- Mechanisn of action: All inverse agonist for mainly H1 receptor
List the 1st generation antihistamine
“Hi Drowsy Children”
Are sedatives
- Hydroxyzine
- Diphenhydramine (Benadryl)
- Chlorpheniramine
What are:
- Hydroxyzine
- Diphenhydramine (Benadryl)
- Chlorpheniramine
1st generation antihistamines (CAN cross the BBB)
List the 2nd generation antihistamine
“CALF”
- Cetirizine
- Azelastine (intranasal)
- Loratadine
- Fexofenadine
What are:
- Cetirizine
- Azelastine (intranasal)
- Loratadine
- Fexofenadine
2nd Generation Antihistamines (can NOT cross BBB)
Histamine are Autocoid. How are the produced?
- Produced by neural and non-neural tissues
Autocoid- physiologically active substance hat is produced by the body and typically has a localized effect of brief duration.
Examples of Autocoids (4)
Monoamines like:
- Histamines
- Serotonin
- Prostaglandins
- Leukotrienes
What are causes (3) for histamine release?
- Respond to injury
- Local hormone (also prostaglandins & leukotrienes)
- Response to an allergic reaction
What can high concentrations of histamine lead to?
Anaphylactic shock
What is the mechanism of drugs that alleviate allergic reactions due to autocoids?
- Inhibit the synthesis
- Block the receptor (still produce autocoids)
What do dugs that activate autocoids (histamine) receptors assist with?
- Inducing labor
- Fighting migraines and headaches
