Antihistamines

Question 1

Cetirizine

Answer 1

Less sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Question 2

Desloratadine

Answer 2

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Question 3

Fexofenadine

Answer 3

Less sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Question 4

Loratadine

Answer 4

less sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Question 5

Bilastine

Answer 5

Less sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Question 6

Adrenaline (epinephrine) (anaphylaxis)

Answer 6

Sympathomimetic

Natural analogue

Question 7

Cyclizine

Answer 7

Piperazine Sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Slight sedative effects.

Question 8

Dexchlorpheniramine

Answer 8

Alkylamine sedating antihistamine

Dexchlorpheniramine is the dextroisomer of chlorphenamine.

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Moderate sedative and anticholinergic effect. more likely to cause paradoxical CNS stimulation.

Question 9

Doxylamine

Answer 9

Ethanolamine Sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Significant sedating and anticholinergic effects. Low incidence of GI adverse effects.

Question 10

Cinnarizine with dimenhydrinate

Answer 10

Sedating antihistamines

Cinnarizine inhibits histamine H1 and H4 receptors and dopamine D2 receptors; it may also block calcium and potassium channels.

Dimenhydrinate inhibits histamine H1 receptors and has anticholinergic activity.

Question 11

Alimemazine

Answer 11

Phenothiazine Sedating antihistamine.

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Has significant sedative and anticholinergic effects. May lower seizure threshold.

Question 12

Pheniramine

Answer 12

Alkylamine sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Moderate sedative and anticholinergic effects. More likely to cause paradoxical effects. low GI incidence effects.

Question 13

Promethazine

Answer 13

Phenothiazine sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Significant sedative and anticholinergic effects.

May lower seizure threshold and cause respiratory depression.

Question 14

Diphenhydramine

Answer 14

Ethanolamine sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Significant sedating and anticholinergic effect. Low incidence of GI effects.

Question 15

Chlorphenamine

Answer 15

Alkylamine sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Moderate sedating and anticholinergic effects.

More likely to cause paradoxical effects. Lower GI effects.

Question 16

Cyproheptadine

Answer 16

Piperidine Sedating antihistamine

Reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form.

Moderate sedative effects; may increase weight.