GIT Drugs
Anti-emetics
Anti-histamines
Diphenhydramine (benadryl)
- good for motion sickness
- can cause paradoxical excitement in cats
- can cause sedation
Meclizine
- good for motion sickness
- can cause paradoxical excitement in cats
- can cause sedation
Dopamine antagonists
Phenothiazines (Prochlorperazine or Acepromazine)
- block many neurotransmitters involve in vomiting, but main job is to block dopamine receptors in the CTZ
- adverse effects = hypotension, sedation and can lower seizure threshold in epileptics
Metoclopramide
- anti emetic effects AND promotes GI motility -> contraindicated in GI obstruction or perforation
- useful for emesis induced by GI disease and chemotherapy
- can cause CNS stimulation
Serotonin (5-HT3) Antagonists
Odansetron and Granisetron
- block central CTZ and peripheral 5-HT3 receptors
- useful for refractory vomiting (chemotherapy, parvo, post op vomiting and pancreatitis)
Mirtazapine
- antiemetic effects in cats and appetite stimulation
Neurokinin-1 antagonists
Maropitant (Cerenia)
- blocks effects of substance P
- can use in dogs and cats
- has some analgesia effects
Glucocorticoids
Dexamethasone
- not indicated for treatment of vomiting but can help to reduce vomiting by inhibiting prostaglandin production (can be added to other antiemetics for refractory vomiting)
Emetics
Peripherally acting
Table salt
Hydrogen peroxide
Ipecac syrup
Centrally acting
Apomorphine
- dogs
Alpha 2 Agonists (Xylazine, dexmedetomidine)
- more reliable in cats
Anti-ulcer
H2 (Histamine) Blockers
- histamine has the greatest effect on ulcers in the stomach
- histamine binds to H2 receptors on parietal cells to increase cAMP and proton pump activity
Cimetidine
- least potent and rarely used now
Ranitidine
- middle potency
Famotidine
- most potent
- less rebound hypersecretion compared to others
- does not inhibit p450 enzymes
Proton Pump Inhibitors
- most potent gastric antisecretory drugs available
Omeprazole
- irreversibly binds the parietal cell (sodium potassium proton pump, which is the final step in gastric acid secretion)
- it is a PROdrug
Mucosal protectants
Sucralfate
- binds to ulcerated area
- requires acidic environment for activation
- good for ulcer healing but not for ulcer prevention
Antacids
- work by neutralizing pH
- formulated as hydroxide bases of aluminum, magnesium and calcium
Misoprostol
- PGE analogue
- increases mucous production, bicarbonate, re-epithelization of mucosa and increases local blood flow
- reduces HCL secretion from parietal cells
- used for the prevention of gastric ulcers
- contraindicated during pregnancy bc it can cause uterine contractions
Prokinetics
- dopamine is inhibitory NT
- Serotonin is excitatory NT
Dopamine Antagonists
Metoclopramide
- blocks inhibitor (dopamine) receptors and stimulates excitatory (serotonin) receptors) on enteric cholinergic nerves = double whammy to promote motility
Domperidone
Serotonin Receptor Modulators
Cisapride
- broadest spectrum prokinetic
Miscellaneous
H2-receptor antagonists
Nizatidine
Ranitidine
Cholinergics
Bethanechol
Anti-diarrheals
Bismuth Subsalicylate
Kaolin/Pectin
Opioids
Loperamide (imodium)
Diphenoxylate
Anticholinergics
- opposite of SLUDGE!
- help to facilitate rectal exams (calms the rectal muscles)
Atropine, hyoscine butylbromide
Propantheline (synthetic anticholinergic)
Laxatives and Cathartics
- laxatives produce soft stool and cathartics produce watery stool
Mineral Oil
White petrolatum
Bulk Laxatives
Methylcellulose and psyllium seed
Stool Softeners
Docusate sodium
Hyperosmotics = salts and sugars
- mannitol, sorbitol and lactulose = the sugars
- magnesium sulfate and sodium sulfate = the salts