GI Drugs- appetite Flashcards
2 issues with appetite
- Obesity
- Animals that don’t want to eat due to illness (especially cats)
Inter species differences
-Cannot compare data from different species
-ex. Many dogs have genetic defect which prevents them from feeling full
Site of physiology appetite control
Satiety center is in the hypothalamus
Hormones involved in appetite control
-cholecystokinin
-Glucagon-like peptide 1 (GLP-1)–> semaglutide- GLP 1 receptor agonist peptide
-Nefstatin/ghrelin
-others
Neurotransmitters involved in appetite control
-Serotonin and peptide YY stimulates satiety
-NE
Dirlotapide/Slentrol
-Not in Canada, in US
-results in decreased fat absorption, so enterocytes keep lipids and feel satiated and tell hypothalamus that they are full
=weight loss due to decreased food intake
-oral solution; start with low dose
-adverse effects: diarrhea, anorexia, emesis, liver enzymes increased
**don’t give to cats (because prone to hepatic lipidosis) or people
Orlistat
-pancreatic lipase inhibitor
-low oral bioavailability (because does not need absorption; works in gut)
-decreased fat digestion/absorption = diarrhea
Mirtazapine
-human antidepressant
-serotonin and NE effects
-stimulates individuals to eat
most effective drug currently for vet med appetite stimulant
Mirtazapine effects
-increase NE release (via pre synaptic alpha 2 receptor inhibition)
-increase specific serotogenic receptor (5-HT1) activity
-antagonist of 5-HT2= increased appetite
-potent antagonist of serotonin receptors (5-HT3)= anti nausea/anti-emetic
-antagonist of histamine receptors= sedation
Mirtazapine in Cats
-Mirataz 2%- transdermal placed on inner pinna of cats ear
-2mg/cat (4cm strip once daily for 14 days)
-polyphagia observed within 36hrs
Mirtazapine pharmacokinetics
-Hepatic metabolism, renal excretion
**need to adjust dose with hepatic or renal disease
-half life= 9-16hrs; some accumulation with repeated doses
**more dose given, longer the half life (RARE/unknown reason)
Mirtazapine as an antidepressant in cats
-Owners have observed increased interaction and vocalization… some antidepressant effects
-These side effects are usually seen at higher dose whereas appetite stimulation can be seen at a lower dose
Glucocorticoids
Steroids= Polyphagia is a common side effect (and “perking up”)
-seen more in dogs than cats
-usually only transient (days to weeks)
-often used in palliative cases (eg.oncology)
Anabolic steroids
Testosterone analogs, suppressing fat and increasing muscle
-related to increased appetite
Anabolic steroids in horses
Labeled for use in chronic illness with weight loss, debilitated or androgenic deficient horses
>Testosterone= controlled drugs
*Vet products are now off the market due to drug abuse
Benzodiazepines
-diazepam (valium) or oxazepam
-occasionally used as appetite stimulates due to GABA effects and inhibition of hypothalamic satiety center
-seemed to have varying effects with different animals
-superseded by mirtazapine
Cyproheptadine
-antihistamine and serotonin receptor blockers which inhibited receptors controlling satiety
-seemed to only work sometimes (“hit or miss”)
Capromorelin
-Only in USA
-Ghrelin receptor agonist working at Brain level
-Cats: usually used for chronic kidney dx
-Dogs: general appetite stimulant
Cannibinoids and appetite
-no evidence for appetite stimulation in dogs and cats