Final Exam - Histamine & Antihistamine

Question 1

What is the primary effect of histamine stimulation of H1 receptors on smooth muscle?

Answer 1

smooth muscle contraction.

Question 2

How does histamine binding to H1 receptors lead to vasodilation?

Answer 2

stimulates the release of nitric oxide, which is a vasodilator. This relaxation of vascular smooth muscles causes vasodilation.

Question 2

What is the consequence of histamine increasing the permeability of post-capillary venules?

Answer 2

allows fluids and cells to pass through the vessel walls, contributing to swelling and inflammation.

Question 3

What sensation is induced by histamine binding to H1 receptors?

Answer 3

induce itch, leading to the sensation of itching.

Question 4

What are the three components of the histamine triple response?

Answer 4

triple response consists of the reddening of the skin, the appearance of surrounding flare (swelling), and the presence of a weal, which is a raised, red, itchy area of skin.

Question 5

Name two sedating antihistamines.

Answer 5

Doxylamine and Promethazine

Question 6

Name three non-sedating antihistamines.

Answer 6

Fexofenadine, Loratadine, and Cetirizine

Question 7

What is a characteristic of sedating antihistamines regarding their ability to cross the blood-brain barrier (BBB)?

Answer 7

can cross the BBB and cause central effects such as sedation and drowsiness

Question 8

What prevents non-sedating antihistamines from crossing the BBB?

Answer 8

their high affinity for P-glycoprotein (P-gP) and their effects on other receptors.

Question 9

What is the primary specificity of non-sedating antihistamines?

Answer 9

are specific for histamine at H1 receptors

Question 10

How do the durations of action differ between sedating and non-sedating antihistamines?

Answer 10

shorter for sedating antihistamines (8-30 hours) and longer for non-sedating antihistamines (24 hours).

Question 11

What potential drug interactions are associated with sedating antihistamines due to their ability to cross the BBB?

Answer 11

may interact with other medications or agents that cause sedation or central nervous system (CNS) depression, such as benzodiazepines, opioid analgesics, and alcohol

Question 12

What distinguishes non-sedating antihistamines in terms of cardiac safety?

Answer 12

are considered cardiac safe

Question 13

In addition to the treatment of allergies, what other uses are associated with sedating antihistamines?

Answer 13

short-term insomnia, as analgesics in combination with paracetamol and codeine, in cough preparations, and for the treatment of motion sickness.

Question 14

What is the primary use of non-sedating antihistamines?

Answer 14

treatment of allergies

Question 15

What are the common therapeutic uses of sedating antihistamines?

Answer 15

treatment of allergies, including allergic rhinitis and hives (skin rashes). They can also be used for prophylactic purposes.

Question 16

In addition to treating allergy, what specific condition is short-term insomnia treated with a sedating antihistamine like doxylamine?

Answer 16

Short-term insomnia can be treated with doxylamine, a sedating antihistamine.

Question 16

How can sedating antihistamines enhance the effects of analgesics like paracetamol and codeine?

Answer 16

Sedating antihistamines, when used in combination with paracetamol and codeine, can enhance the effects of these analgesic medications.

Question 17

What is a common inclusion for sedating antihistamines in cough preparations?

Answer 17

Sedating antihistamines are often included in cough preparations.

Question 18

What therapeutic uses are common for non-sedating antihistamines, particularly in the treatment of allergies?

Answer 18

treatment of allergies, including allergic rhinitis and hives (skin rashes). They can also be used for prophylactic purposes.