H1 antagonists

Question 1

H1 receptor antagonist

Answer 1

Class: N/A

Mech: H1 receptor antagonist; rapidly absorbed orally, widely distributed, rapidly metabolized via liver microsomes

Thera: Allergic reactions, motion sickness, N-V in pregnancy, sleep aids

Tox: Sedation, antimuscarinic effects, poisoning with convulsions (esp with children) allergy, local anesthesia

Misc: Older agents cross CNS to cause central effects

Question 2

Diphenhydramine (Benadryl)

Answer 2

Class: Ether/ethanolamine derivative

Mech: H1 receptor antagonist

Thera: N/A

Tox: Antimuscarinic, sedating

Question 3

Tripelennamine

Answer 3

Class: Ethylenediamine derivative

Mech: H1 receptor antagonist

Thera: OTC sleep aid

Question 4

Cyclizine

Answer 4

Class: Piperazine deriv

Mech: H1 receptor antagonist

Thera: Motion sickness

Question 5

Promethazine

Answer 5

Class: Phenothiazine deriv

Mech: H1 receptor antagonist

Thera: Antiemetic

Tox: Anti-muscarinic, sedating

Question 6

Chlorpheniramine

Answer 6

Class: Alkylamine deriv.

Mech: H1 receptor antagonist

Thera: Component of cold medicine

Tox: Less sedating

Question 7

Loratidine

Answer 7

Class: Piperidine deriv

Mech 2nd gen H1 antagonist

Thera: Allergic rhinitis

Tox: No sedation
Cardiovascular effects possible with high doses

Misc: Poorly crosses BBB so fewer central SEs

Question 8

Fexofenadine

Answer 8

Class: Piperidine deriv

Mech 2nd gen H1 antagonist

Thera: Allergic rhinitis

Tox: No sedation
Cardiovascular effects possible with high doses

Misc: Poorly crosses BBB so fewer central SEs

Question 9

Azelastine

Answer 9

Class: N/A

Mech 2nd gen H1 antagonist

Thera: Allergic rhinitis (intranasal spray), allergic conjunctivitis (ophthalmic solution)

Tox: No sedation

Misc: Poorly crosses BBB so fewer central SEs

Question 10

Cetirizine

Answer 10

Class: N/A

Mech 2nd gen H1 antagonist

Thera: Allergic rhinitis

Tox: No sedation

Misc: Poorly crosses BBB so fewer central SEs