Drugs Against Allergies

Question 1

H1 Receptor Targets

Answer 1

• Vascular vasodilation mediated by NO & PG’s from endothelial cells
• Increased permeability of post capillary venules-> edema
• Coronary vasoconstriction and decreased AV conduction
• Bronchioconstriction, Increased mucus viscosity, Stimulation of vagal sensory nerve endings-> cough and bronchospasms
• Increased intestinal motility and secretions
• Cutaneous pain and itching

Question 2

H2 Receptor Targets

Answer 2

• Vascular vasodilation mediated by cAMP in vascular smooth muscle
• In the heart to increased inotropy and chronotropy
• Stomach to increase acid, fluid and pepsid secretion

Question 3

Diphenhydramine

Answer 3

• Benadryl
• First Gen H1 antagonist (sedative), penetrates blood brain barrier
• Treat allergic rhinitis, and skin allergies

Question 4

Dimenhydrinate

Answer 4

• Dramamine
• 1st Gen H1 antagonist, 1:1 Diphenhydramine : 8-CL-Theophylline
• Slower acting
• H1 and anti-mucerinic activity-> good antiemetic
• Treat nausea and motion sickness
• Meclizine, less drowsiness than original

Question 5

Doxylamine

Answer 5

• Nyquil, 1st Gen
• Antiallergy as good as diphenhydramine
• Most potent OTC sedative sleep aid
• Other Clemastine

Question 6

Chlorpheniramine

Answer 6

• Chlor-Trimeton,1st gen H1

- Also SSRI

Question 7

Hydroxyzine

Answer 7

• 1st Gen H1
• Crosses blood brain barrier also antipsychotic
• Metabolite Cetirizine does not cross barrier, actual H1 antagonist

Question 8

Cetirizine

Answer 8

-Zyrtec, 2nd Gen H1(non-sedative)

Question 9

Loratadine

Answer 9

• Claritin, 2nd Gen H1
• 8hr half-life, metabolite: Desloratadine(Clarinex), 28 hr
• Fexofenadine, highly selective to H1

Question 10

Cromolyn

Answer 10

• Mast cell stabilizer
• Prevents Asthma attack
• Prevents mediator release by mast cells by blocking Ca influx
• inhalation or eyedrops
• Also Nedocromil

Question 11

Montelukast

Answer 11

• Cys-LT-R Antagonist
• Asthma therapy add-on
• Prevent exercise and aspirin induced asthma
• 5hr
• Zafirlukast, 10hr

Question 12

Zileuton

Answer 12

• Only approved 5-lipoxygenase inhibitor
• Blocks production of Leukotrienes
• Not useful in treatment of attacks

Question 13

1st Gen Adverse side effects

Answer 13

• Sedation
• Dizziness, fatigue
• Anti-muscerinic effects: Dry mouth, Blurred vision, Constipation, Urinary retention

Question 14

1st Gen Drug interactions

Answer 14

• Additive with classical muscerinic antagonists

- Potentiates: Opiods, sedatives, General and narcotic analgesics, alcohol

Question 15

Allergy response pathway

Answer 15

• Allergen taken up by plasma B cells-> IgE antibody produced and attached to mast cell
• When mast cell is exposed to allergen-> inflamatory mediators are released
• Primary mediators(initial): Granule contents: Histamine, Proteases, Chemotactic factors
• Secondary mediators(late-phase): Cytokines, Arachidonic acid(PG’s,LT’s)