Antihistamine Drugs

Question 1

Ethanolamines

Answer 1

Diphenhydramine (Benadryl) 
Uses: Hives, itching, allergy symptoms 
Side effects: Dizziness, drowsiness 
-metabolized by CYP P450 -> lots of drug to drug interactions
First Generation H1 Antihistamines

Question 2

Ethylenediamines

Answer 2

Tripelennamine (PBZ)
Uses: Sneezing, runny nose, itching, allergies
Side Effects: Sleepiness, fatigue, or dizziness
First Generation H1 Antihistamines

Question 3

Alkylamines

Answer 3

Chlorpheniramine (Chlor-Trimeton) 
Uses: Runny nose, sneezing, itching and watery eyes- allergies 
Side effects: Dizziness, drowsiness 
Metabolized by CYP 
First Generation H1 Antihistamines

Question 4

Phenothiazines

Answer 4

Promethazine (phenergan) 
Uses: Prevents motion sickness, treats nausea and vomiting; pain after surgery; sedative or sleep aid 
-Anti-emetics and motion sickness 
Side effects: Drowsiness, dizziness 
First Generation H1 Antihistamines

Question 5

Piperazines

Answer 5

Hydroxyzine (Atarax, Vistaril)
Use: To control nausea and vomiting
Side effects: Drowsiness, Dizziness

Cyclizine (Marezine), Meclizine (Antivert)

• Motion sickness or symptoms of vertigo
• Drowsiness, weakness
• Strong anti-emetics

First Generation H1 Antihistamines

Question 6

Piperidines

Answer 6

Cyproheptadine (Periactin)
Use: Symptoms of allergic reactions
Side effects: Drowsiness, weakness
- both antihistamine and antiserotonin

First Generation H1 Antihistamines

Question 7

Second-Generation Piperazines

Answer 7

Cetirizine (Zyrtec)
Use: Treat cold or allergy symptoms
Side Effects: Drowsiness, dizzinesss ( low)

Question 8

Second-Generation Piperidines

Answer 8

Loratadine (Claritin)
Use: Allergy Symptoms
Side Effects: Stomach pain
Metabolized by CYP P450 metabolism prolonged by grapefruit

Fexodenadine

Question 9

Levocertirizine (Xyzal)

Answer 9

Reduced pro inflammatory cytokines in cultured airway cell lines
-Greater potency and @ smaller dose
-Active R-enatiomer of cetirizine
3rd Generation H1 Antihistamine

Question 10

Desloratadine (Clarinex, 2001)

Answer 10

Active metabolite of Loratadine

-Drug action not influenced by inhibitors of CYP

Question 11

Cimetidine (Tagamet)

Answer 11

• inhibits multiple hepatic cytochrome p-450 (CYP) drug metabolism pathways; potential for adverse drug-drug interactions
• H2 antihistamine

Question 12

Ranitidine (Zantac)

Answer 12

-Exhibits some CYP interference but

Question 13

Famotidine (Pepcid)

Answer 13

• Most potent H2 antihistamine

- No CYP interference

Question 14

Nizatidine (Tazac, Axid)

Answer 14

• No CYP interference

- H2 antihistamine

Question 15

Cromolyn and Nedocromil

Answer 15

• Used prophylactically
• Block Ca2+ entry -> preventing degranulation
• Low water solubility; poorly absorbed across GI tract
• must be inhaled
• Used to treat allergic bronchospasm (inhaler) and rhino conjunctivitis (nasal spray)
• Prevent asthma attacks