Respiratory (Anti-Histamines - H1 receptor antagonists)

Question 1

Examples of drug (Anti-Histamines - H1 receptor antagonists)

Answer 1

• Chlorpheniramine
• Desloratidine
• Fexofenadine
• Hydroxyzine
• Note that a number of other drugs such as anti-emetics and anti-psychotics have anti-histamine activity. H2 antagonists are discussed separately.

Question 2

Mechanism of action (Anti-Histamines - H1 receptor antagonists)

Answer 2

• Antihistamine; H1 receptor antagonist.

- Inhibits histamine-mediated contraction and vasodilation of the bronchial smooth muscle.

Question 3

Indications (Anti-Histamines - H1 receptor antagonists)

Answer 3

• Anaphylaxis
• Hay fever
• Urticaria
• Sedation

Question 4

Side effects (Anti-Histamines - H1 receptor antagonists)

Answer 4

• Drowsiness

- Tinnitus

Question 5

Important pharmacokinetics/pharmacodynamics (Anti-Histamines - H1 receptor antagonists)

Answer 5

• Renally excreted
• Sedation arises from central nervous system H1 antagonism (second generation H1 antagonists do not cross the blood brain barrier in therapeutic doses).

Question 6

Patient information (Anti-Histamines - H1 receptor antagonists)

Answer 6

• Do not operate heavy machinery.

- Do not drive.