Antihistamines and Autacoid-Modifying Agents Flashcards
Characteristics of Autacoids
- act like local hormaones
- short duration of action
- act near the site of synthesis/release
- not blood borne
Where does histamine synthesis occur?
Mast cells and basophils, ECL cells and CNS
Where is histamine metabolized?
Liver
What does histamine do?
- mediator of inflammation, anaphylaxis and gastric acid secretion
- neurotransmitter
H1-antihistamines uses
Allergy, itching, nausea, motion sickness and insomnia
Diphenhydramine uses
- acute allergic reaction
- antipruritic
- prevent reactions
- motion sickness
- mast cell tumor
Does diphenhydramine cross the BBB/
Yes
Adverse effects of diphenhydramine
CNS and anticholinergic
Cyproheptadine mechanism
Serotonin (5-HTP) antagonist
Cyproheptadine effects
- appetite stimulant
- antipruritic effect
- horses: photic head shaking and PPID
Cyproheptadine adverse effects
CNS and anticholinergic
Meclizine uses
-motion sickness and vestibular disease
Meclizine mechanism of action
- Only partial understood
- antiemetic action through CTZ
H2 Antihistamines characteristics
- reversible competitive antagonists
- gastric parietal cells
- reduce gastric acid secretion
H3 and H4 antihistamine characteristics
- not approved for clinical use
- experimental models
- improve attention and wakefulness
Serotonin synthesized from where, and found where? And stored where?
- tryptophan
- found in GI tissues (ECL cells), CNS and platelets
- ECL cells 5-HT is stored in platelets
Signs of serotonin overdose
- neuro signs: seizures, depression, tremors, hyperestheisa and ataxia
- Gi signs: vomiting, diarrhea, abdominal pain, hypersalivation
- other: hyperthermia, blindness
Amphetamine inhibits what
Serotonin storage
Amphetamines displace what
5-HT, dopamine and norepinephrine from storage vesicles
Monoamin oxidase inhibitors inhibit? Types?
- inhibit serotonin degradation
- MAOI-a and MAOI-b
Selegiline type?
MOAI-b but also MAOI-a
Selegiline treats? By?
-canine cognitive dysfunction by increasing dopamine activity
Reuptake inhibitors do what
Increase extracellular 5-HT to treat anxiety, depression and OCD
Clomipramine type?
Tricyclics antidepressant
Clomipramine treats
OCD, anxiety and dominance aggression. Only FDA approved drug in dogs
Fluoxetine type
Selective-serotonin reuptake inhibitor
Fluoxetine treats?
Separation anxiety in conjunction with behavior modification plan
Adverse effects of fluoxetine
Anorexia and seizures
Mirtazapine type
5-HT2 and 5-HT3 inhibitor
- central alpha 2 receptor inhibitor (increase in NE)
Mirtazapine effects
- appetite stimulant
- antiemetic
- atypical antidepressant
- adverse: drowsiness/sedation, vocalization, tachycardia
Trazodone type
5-HT2 inhibitor and SSRI
-adjunctive anxiolytic
Trazadone treats
Hospitalization related anxiety and post op recovery
Trazadone effects
- GI signs, ataxia, hypotension
- less cardiovascular effects
Cisapride type
-5-HT4 agonist
Cisapride effects
- enhances AcH release
- prokinetic
- adverse: well tolerated
Cisapride treats
GI stasis, reflux esophagitis, constipation/megacolon
Ondansetron type
- serotonin receptor agonist
- receptors in vagal nerve terminals and CTZ
- controversial in cats, well tolerated in dogs
