Antihistamines and Allergy Treatment

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Questions and Answers

What is the primary role of antihistamines in treating allergies?

Stimulate the release of gastric acid

Inhibit the production of antibodies

Enhance neurotransmission in the central nervous system

Block H1 receptors and prevent histamine binding (correct)

Which generation of antihistamines is more likely to cause sedation?

2nd Generation

Both generations cause sedation equally

1st Generation (correct)

Neither generation causes sedation

Which of the following is an example of a 2nd generation antihistamine?

Cetirizine (correct)

Chlorpheniramine

Doxylamine

Diphenhydramine

What is the mechanism of action of 2nd generation antihistamines?

Block peripheral H1 receptors with minimal sedation Signup and view all the answers

Which receptor is primarily involved in allergic responses?

H1 receptors Signup and view all the answers

Antihistamines neutralize or mark which substances for destruction?

Antigens Signup and view all the answers

What is a notable side effect of 1st generation antihistamines?

Sedation due to crossing the blood-brain barrier Signup and view all the answers

Which factors are associated with H3 and H4 receptors?

neurotransmisson and immune function Signup and view all the answers

What effect does histamine have on blood vessels?

Dilation of capillaries Signup and view all the answers

Which of the following are effects of histamine on the cardiac system?

Rapid heart rate Signup and view all the answers

What condition can result from the leaky capillaries due to histamine?

Nasal congestion Signup and view all the answers

Which of the following is NOT an indication for antihistamines?

Cardiac arrhythmias Signup and view all the answers

How does histamine lead to gastrointestinal upset?

By increasing smooth muscle contraction in the stomach Signup and view all the answers

What role does histamine play in the occurrence of hives (urticaria)?

It increases capillary permeability Signup and view all the answers

Which smooth muscle organ is NOT influenced by histamine according to its actions?

Heart Signup and view all the answers

What is a potential side effect of using antihistamines as sleep aids?

Morning grogginess Signup and view all the answers

What mechanism does cromolyn sodium use to prevent allergic responses?

Prevents histamine release from mast cells Signup and view all the answers

Which receptors are primarily involved in mediating allergic responses?

H1-receptors Signup and view all the answers

Which additional effects do antihistaminics possess apart from inhibiting histamine actions?

Local anesthetic activity Signup and view all the answers

What is the recommended administration strategy for cromolyn sodium?

Prophylactically before exposure to allergens Signup and view all the answers

Which of the following is NOT a use for antihistaminics?

Treatment of bacterial infections Signup and view all the answers

How does smooth muscle in blood vessels help regulate blood pressure?

By contracting or relaxing to control vessel diameter Signup and view all the answers

Which role do arrector pili muscles play in the skin?

Causing goosebumps in response to cold or fear Signup and view all the answers

Which of the following structures contains smooth muscle?

Bronchi and bronchioles in the respiratory tract Signup and view all the answers

What distinguishes smooth muscle from skeletal muscle?

Smooth muscle is under unconscious control Signup and view all the answers

In which part of the female reproductive system is smooth muscle primarily involved?

Uterus, during the menstrual cycle and childbirth Signup and view all the answers

What is the primary function of smooth muscle in the ureters?

Propel urine from kidneys to the bladder Signup and view all the answers

Which part of the body includes smooth muscle to regulate light entry?

The iris of the eye Signup and view all the answers

What characteristic distinguishes cardiac muscle from both skeletal and smooth muscle?

It is striated and under involuntary control Signup and view all the answers

What is a common side effect of antihistamines?

Dry mouth Signup and view all the answers

Which of the following antihistamines is considered a first-generation antihistamine?

Diphenhydramine Signup and view all the answers

What distinguishes second-generation antihistamines from first-generation?

Selective blocking of H1 receptors Signup and view all the answers

Which first-generation antihistamine is known for its high sedating effects?

Hydroxyzine Signup and view all the answers

What is the mechanism of action of Cromolyn Sodium?

Inhibiting mast cell degranulation Signup and view all the answers

Which of the following is NOT a side effect associated with first-generation antihistamines?

Insomnia Signup and view all the answers

Which of the following medications is categorized as a second-generation antihistamine?

Cetirizine Signup and view all the answers

What is the primary action of cromolyn sodium in relation to mast cells?

It stabilizes the cell membrane of mast cells. Signup and view all the answers

Which type of drug is administered to alleviate symptoms of an acute reaction after histamine is released?

Antihistaminic drugs Signup and view all the answers

What triggers the activation and subsequent degranulation of mast cells?

Injury or infections. Signup and view all the answers

What is the condition called characterized by redness of the skin due to capillary dilation?

Erythema Signup and view all the answers

Which of the following effects is NOT produced by histamine on various tissues?

Promotion of muscle relaxation in intestines Signup and view all the answers

Where is histamine predominantly found in the human body?

In mast cells and basophilic white blood cells Signup and view all the answers

What term describes the approach to prevent the onset of symptoms before a reactive process occurs?

Prophylaxis Signup and view all the answers

Which of the following correctly distinguishes between antiallergic and antihistaminic drugs?

Antiallergic drugs block the release of histamine from mast cells. Signup and view all the answers

Study Notes

Allergies, Antihistamines, and Antiallergics

Allergies occur when the immune system reacts to a harmless substance.
Allergens are substances that cause allergic reactions. Examples include pollen, dust mites, animal dander, certain foods, and insect stings.
Antigens trigger an immune response. They are often proteins found on the surface of pathogens like bacteria and viruses.
Antibodies are proteins produced by the immune system in response to antigens. They bind to antigens to neutralize or destroy them.

Allergy Terms

Allergy: The immune system's response to a foreign substance that's usually harmless to others.
Allergen: Any substance capable of triggering an allergic reaction.
Antigen: A substance that triggers an immune response.
Antibody: A protein produced by the immune system in response to an antigen.
H1-receptor: A receptor that, when bound to histamine, activates symptoms of allergies like itching, swelling, and redness.
H2-receptor: A receptor in the stomach that controls acid production.
Histamine: A chemical released by the immune system during allergic reactions; causes itching, swelling, and redness.
Rhinitis: Inflammation of the nasal mucous membranes, causing runny/stuffy nose, sneezing, and itching; can be allergic or non-allergic, like viral.
Urticaria (Hives): Skin condition characterized by raised, itchy welts or hives. Often caused by allergic reactions.
Eczema: Skin condition characterized by inflammation, dryness, itching, and rash that is unrelated to allergies.
Erythema: Redness of the skin due to increased blood flow.
Dermatitis: Skin inflammation causing redness, swelling, and itching: unrelated to allergies.
Anaphylaxis: Severe, potentially life-threatening allergic reaction that requires immediate medical attention.

Antihistamines

Antihistamines: Medication that blocks the effects of histamine by binding to H1 receptors.
Antihistamines reduce symptoms of allergies such as itching, swelling, and runny nose.
First-generation antihistamines: Often cause drowsiness, they cross the blood-brain barrier, and are more likely to be sedating.
Second-generation antihistamines: Less likely to cause drowsiness. They don't cross the blood-brain barrier as easily, and fewer sedative effects.

Antihistamine - General Info

Competitively blocks H1 receptors, preventing histamine from binding and exerting its effects.
H1 receptors are primarily involved in allergic responses.
H2 receptors are involved in gastric acid secretion.
H3 and H4 receptors are involved in neurotransmission and immune function.

First Generation Antihistamines

Diphenhydramine (Benadryl), Chlorpheniramine (Chlor-Trimeton), Doxylamine (Unisom), Promethazine (Phenergan), Hydroxyzine (Atarax, Vistaril), Brompheniramine (Dimetapp), Meclizine (Antivert, Bonine), Cyproheptadine (Periactin).

Second Generation Antihistamines

Loratadine (Claritin), Cetirizine (Zyrtec), Fexofenadine (Allegra), Desloratadine (Clarinex), Levocetirizine (Xyzal).

Indications for Antihistamines

Acute allergic reactions: Hay fever, insect bites, pet dander, minor food or drug allergies.
Dry nasal secretions: Often found in cough and cold medications.
Sleep aids: Due to sedative properties, but less so in later generation.
Nausea/Vomiting/Motion Sickness: Some are used to reduce this.

Other Considerations

Drug interactions: Older generation antihistamines can have significant sedative effects when combined with other CNS depressants like hypnotics, alcohol, or other sedatives.
Adverse effects of antihistamines: Drowsiness, dry mouth, hypotension, rapid heartbeat, anorexia, urinary retention, etc.; often more common in first-generation drugs.
Contraindications: Patients with cardiovascular disease, pre-existing hypertension, urinary retention, or those taking specific medications are usually advised not to use certain antihistamines.
Cromolyn Sodium: An antiallergic drug not an antihistamine, it inhibits the release of inflammatory mediators preventing mast cell degranulation.

Additional Notes

Different types of antihistamines have different strengths, side effects, and indications.
Always consult with a healthcare professional before taking any medication, especially when pregnant or breastfeeding.
The information here is for educational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment.

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Description

This quiz covers fundamental concepts about antihistamines and their role in treating allergies. Key areas include the differences between first and second generation antihistamines, their mechanisms of action, and their effects on the body. Test your knowledge on the primary functions and side effects associated with these important medications.