Antihistamines and Autacoid-Modifying Agents

Question 1

Characteristics of Autacoids

Answer 1

• act like local hormaones
• short duration of action
• act near the site of synthesis/release
• not blood borne

Question 2

Where does histamine synthesis occur?

Answer 2

Mast cells and basophils, ECL cells and CNS

Question 3

Where is histamine metabolized?

Answer 3

Liver

Question 4

What does histamine do?

Answer 4

• mediator of inflammation, anaphylaxis and gastric acid secretion
• neurotransmitter

Question 5

H1-antihistamines uses

Answer 5

Allergy, itching, nausea, motion sickness and insomnia

Question 6

Diphenhydramine uses

Answer 6

• acute allergic reaction
• antipruritic
• prevent reactions
• motion sickness
• mast cell tumor

Question 7

Does diphenhydramine cross the BBB/

Answer 7

Yes

Question 8

Adverse effects of diphenhydramine

Answer 8

CNS and anticholinergic

Question 9

Cyproheptadine mechanism

Answer 9

Serotonin (5-HTP) antagonist

Question 10

Cyproheptadine effects

Answer 10

• appetite stimulant
• antipruritic effect
• horses: photic head shaking and PPID

Question 11

Cyproheptadine adverse effects

Answer 11

CNS and anticholinergic

Question 12

Meclizine uses

Answer 12

-motion sickness and vestibular disease

Question 13

Meclizine mechanism of action

Answer 13

• Only partial understood

- antiemetic action through CTZ

Question 14

H2 Antihistamines characteristics

Answer 14

• reversible competitive antagonists
• gastric parietal cells
• reduce gastric acid secretion

Question 15

H3 and H4 antihistamine characteristics

Answer 15

• not approved for clinical use
• experimental models
• improve attention and wakefulness

Question 16

Serotonin synthesized from where, and found where? And stored where?

Answer 16

• tryptophan
• found in GI tissues (ECL cells), CNS and platelets
• ECL cells 5-HT is stored in platelets

Question 17

Signs of serotonin overdose

Answer 17

• neuro signs: seizures, depression, tremors, hyperestheisa and ataxia
• Gi signs: vomiting, diarrhea, abdominal pain, hypersalivation
• other: hyperthermia, blindness

Question 18

Amphetamine inhibits what

Answer 18

Serotonin storage

Question 19

Amphetamines displace what

Answer 19

5-HT, dopamine and norepinephrine from storage vesicles

Question 20

Monoamin oxidase inhibitors inhibit? Types?

Answer 20

• inhibit serotonin degradation

- MAOI-a and MAOI-b

Question 21

Selegiline type?

Answer 21

MOAI-b but also MAOI-a

Question 22

Selegiline treats? By?

Answer 22

-canine cognitive dysfunction by increasing dopamine activity

Question 23

Reuptake inhibitors do what

Answer 23

Increase extracellular 5-HT to treat anxiety, depression and OCD

Question 24

Clomipramine type?

Answer 24

Tricyclics antidepressant

Question 25

Clomipramine treats

Answer 25

OCD, anxiety and dominance aggression. Only FDA approved drug in dogs

Question 26

Fluoxetine type

Answer 26

Selective-serotonin reuptake inhibitor

Question 27

Fluoxetine treats?

Answer 27

Separation anxiety in conjunction with behavior modification plan

Question 28

Adverse effects of fluoxetine

Answer 28

Anorexia and seizures

Question 29

Mirtazapine type

Answer 29

5-HT2 and 5-HT3 inhibitor | - central alpha 2 receptor inhibitor (increase in NE)

Question 30

Mirtazapine effects

Answer 30

- appetite stimulant - antiemetic - atypical antidepressant - adverse: drowsiness/sedation, vocalization, tachycardia

Question 31

Trazodone type

Answer 31

5-HT2 inhibitor and SSRI | -adjunctive anxiolytic

Question 32

Trazadone treats

Answer 32

Hospitalization related anxiety and post op recovery

Question 33

Trazadone effects

Answer 33

- GI signs, ataxia, hypotension | - less cardiovascular effects

Question 34

Cisapride type

Answer 34

-5-HT4 agonist

Question 35

Cisapride effects

Answer 35

- enhances AcH release - prokinetic - adverse: well tolerated

Question 36

Cisapride treats

Answer 36

GI stasis, reflux esophagitis, constipation/megacolon

Question 37

Ondansetron type

Answer 37

- serotonin receptor agonist - receptors in vagal nerve terminals and CTZ - controversial in cats, well tolerated in dogs