LT Pharma: Antihistamine Flashcards
How many types of histamine receptors are known to mediate the effects of histamine?
a) Two
b) Four
c) Six
d) Eight
b) Four
(H1, H2, H3, and H4 receptors)
How is histamine synthesized in the body?
a) From the amino acid lysine
b) From the amino acid histidine by histidine decarboxylase
c) From the amino acid tryptophan
d) From the amino acid glutamine
b) From the amino acid histidine by histidine decarboxylase
Where is histamine primarily stored in the body?
a) Lymph nodes
b) Liver
c) Granules within mast cells and basophils
d) Kidneys
c) Granules within mast cells and basophils
Histamine is found in most tissues, particularly the?
Lungs, skin, & GI
H1 receptor locations & their corresponding functions?
(4 mentioned)
H2 receptor locations & their corresponding functions?
(2 were mentioned)
- Cardiac muscles → Cardiac stimulation
- Parietal cells of stomach → Stimulates gastric acid secretion
H3 receptor location & its corresponding function?
(1 was mentioned)
Presynaptic neurons → Inhibit neurotransmitter release
H4 receptor locations & their corresponding functions?
(1 was mentioned)
Mast cells & eosinophils → Stimulation of chemotaxis
What triggers the release of histamine from mast cells during inflammatory or allergic reactions?
a) Direct interaction with complement fragments C3a and C5a
b) Direct interaction with IgG antibodies
c) Interaction of an antigen with IgE bound to sensitized mast cells and basophils
d) Direct interaction with histamine receptors
c) Interaction of an antigen with IgE bound to sensitized mast cells and basophils
In addition to inflammatory or allergic reactions, what other mechanisms can lead to the release of histamine?
a) Interaction with IgA antibodies
b) Direct release by complement fragments C3a and C5a, as well as by some drugs
c) Interaction with IgM antibodies
d) Direct release by T lymphocytes
b) Direct release by complement fragments C3a and C5a, as well as by some drugs
Which drugs can cause the release of histamine?
d-tubocurarine or morphine
Key members of 1st generation Antihistamines?
diphenhydramine, chlorpheniramine, doxylamine, etc.
Key members of 2nd generation Antihistamines?
loratadine, desloratadine, cetirizine, fexofenadine.
mnemonic: lazy dogs carry fleas
The major pathological roles of histamine are in?
(3 were mentioned)
-
Allergic diseases
- allergic rhinitis (hay fever)
- allergic conjunctivitis
- asthma
- urticaria (both acute and chronic), etc. - Anaphylactic shock
- Hypersecretion of acid in peptic ulcers.
What is the primary MOA of antihistamines?
a) Inhibition of histamine formation
b) Blockade of histamine H1 receptors
c) Activation of histamine H2 receptors
d) Stimulation of histamine release
b) Blockade of histamine H1 receptors
Which generation of antihistamines is characterized by high lipophilicity and sedative effects?
a) 3rd generation
b) 1st generation
c) 2nd generation
d) 4th generation
b) 1st generation
Which group of antihistamines is more likely to enter the central nervous system (CNS) and cause sedation?
a) 2nd generation
b) 1st generation
c) 3rd generation
d) 4th generation
b) 1st generation
they’re more lipophillic than 2nd gen
Which generation of antihistamines is known for its autonomic receptor-blocking effects?
a) 1st generation
b) 2nd generation
c) 3rd generation
d) 4th generation
a) 1st generation
Which generation of antihistamines is generally long-acting and non-sedating?
a) 1st generation
b) 2nd generation
c) 3rd generation
d) 4th generation
b) 2nd generation
Which group of antihistamines is known to have an anti-motion sickness effect?
a) 2nd generation
b) 1st generation
c) 3rd generation
d) 4th generation
b) 1st generation
e.g. diphenhydramine
What is the most important clinical use of antihistamines (H1 blockers)?
a) Treatment of asthma
b) Treatment of allergic diseases such as allergic rhinitis and urticaria
c) Treatment of bacterial infections
d) Treatment of gastrointestinal disorders
b) Treatment of allergic diseases such as allergic rhinitis and urticaria
both 1st & 2nd generation
Why are antihistamines ineffective in the treatment of asthma?
a) They do not target the correct receptors
b) Other mediators, such as cysteinyl leukotrienes, play a more significant role in the pathophysiology of asthma
c) Asthma is not an allergic disease
d) Antihistamines cause bronchoconstriction
b) Other mediators, such as cysteinyl leukotrienes, play a more significant role in the pathophysiology of asthma
What is the moa of antihistamines in the prevention and treatment of motion sickness?
a) Blocking of serotonin receptors
b) Blockade of H1 receptors
c) Enhancement of dopamine release
d) Inhibition of acetylcholine activity
(mention which drug does that)
b) Blockade of H1 receptors involved in motion sickness symptoms
e.g. diphenhydramine
How are antihistamines utilized in the treatment of insomnia?
a) By enhancing histamine release
b) By stimulating H1 receptors in the CNS
c) Exploiting their sedative side effect
d) By blocking acetylcholine receptors
(mention which drug does that)
c) Exploiting their sedative side effect
e.g. doxylamine
What symptoms of allergic diseases do antihistamines primarily target by blocking H1 receptors?
a) Fever and chills
b) Vascular permeability, vasodilation, and itch
c) Cough and sore throat
d) Muscle weakness and fatigue
b) Vascular permeability, vasodilation, and itch
In the treatment of motion sickness, which antihistamine is commonly used?
a) Diphenhydramine
b) Loratadine
c) Desloratadine
d) Fexofenadine
a) Diphenhydramine
In the treatment of insomnia, which antihistamine is commonly used?
a) Doxylamine
b) Loratadine
c) Desloratadine
d) Fexofenadine
a) Doxylamine
What is the most important side effect associated with 1st generation antihistamines?
a) Sedation
b) Dry mouth
c) Blurred vision
d) Cardiotoxicity
a) Sedation
(they’re all correct but sedation was mentioned to be the most important)
Which generation of antihistamines is primarily associated with anti-muscarinic side effects such as dry mouth and blurred vision?
a) 1st generation
b) 2nd generation
c) 3rd generation
d) 4th generation
a) 1st generation
What adverse effect is specifically associated with 2nd generation antihistamines, leading to the withdrawal of some early drugs?
a) Sedation
b) Dry mouth
c) Cardiotoxic effect, especially QT interval prolongation
d) Drug interactions
c) Cardiotoxic effect, especially QT interval prolongation
(an adverse effect of antihistamines)
How do most antihistamines interact with other drugs?
a) By enhancing their effects
b) By inhibiting their metabolism
c) By being metabolized by cytochrome P450 enzymes and affecting their metabolism
d) By blocking their receptors
c) By being metabolized by cytochrome P450 enzymes and affecting their metabolism
Which 2nd generation drugs have been withdrawn due to having a Cardiotoxic side effect? especially the prolongation of QT intervals?
terfenadine and astimiozole
