Antihistamines - diphenhydramine (__________), dimenhydrinate (_________)

1. Antihistamines- diphenhydramine (__________), dimenhydrinate (_________) • Used for vomiting caused by motion sickness or inner ear abnormalities. • Decrease impulses sent from the vestibular apparatus by blocking H1 receptors at the CRTZ. • More effective in dogs as they have larger numbers of H1 receptors on the CRTZ. • May cause sedation and decrease the response to an allergy test. • Although injectables are available, oral dose can be given prophylactically.

2. Prokinetic- metoclopramide (________) • Blocks receptors in the CRTZ, but is known for its local effect: Increasing upper GI motility. • DO NOT GIVE WITH GI OBSTRUCTION • More effective in dogs than cats as it targets dopamine receptors. • Now found to increase risk of seizure activity in animals prone to seizures. • Atropine and narcotics can negate its effects.

3. Serotonin Receptor Antagonists- ondansetron (_________), dolasetron (__________) • Also called 5-HT3 receptor antagonists, these drugs block serotonin (a neurotransmitter) receptors on the vagus nerve and in the CRTZ. • Used when emesis is caused by chemotherapy drugs, severe parvovirus, and pancreatitis

4. NK-1 Receptor Antagonist- maropitant citrate (_________) • Inhibit the binding of Substance P (a neuropeptide) to neurokinin receptors in the Emetic center. • Considered a broad-spectrum antiemetic • Injectable form is approved for use in both dogs and cats. Oral form is for dogs. • Injection may be painful. • Can be given prophylactically to prevent motion sickness (without causing drowsiness), but also used to treat vomiting from other causes.

5. ANTIDIARRHEALS Change intestinal motility or reduce secretions. loperamide, diphenoxylate atropine, aminopentamide, propantheline bismuth subsalicylate sulfasalazine kaolin, pectin bismuth, barium

6. Motility Modifiers • Increase segmental contractions and/or decrease peristaltic contractions to slow the movement of feces.

7. Opiod family- loperamide (__________), diphenoxylate (__________) • Opiods are known to cause constipation. These medications use this as a benefit. • Increase segmental contractions, decrease peristalsis, and decrease intestinal secretions in patients with diarrhea. • Can cause sedation, especially in collie-related breeds. • Atropine is often added to discourage abuse (will cause dry mouth, dilated pupils). • Lomotilis a Class V controlled substance, Immodiumis OTC

8. Anticholinergics- atropine, scopolamine • Work against the effects of the neurotransmitter Acetylcholine. Also called parasympatholytics. Remember, the parasympathetic nervous system stimulates intestinal motility. • Effects often noted after use in surgical patients • Use with caution in animals who are already in Sympathetic mode (tachycardia, ileus)

9. Antisecretory agents • Stimulation of the cells that line the GI tract can result in secretion of ions that pull water with them into the gut lumen. • When inflammation damages the tight junctions between GI cells, sugars, proteins, and red blood cells can also be lost in the lumen. • These animals are at risk for dehydration. • The opioids and serotonin antagonist drugs listed previously are also in this category.

10. bismuth subsalicylate (_____________), (___________) • Bismuth coats the mucosa and has an anti-bacterial effect (Helicobacter), while salicylate (aspirin-like compound) decreases inflammation and secretions. • Recommended doses are typically safe for cats, but owners should be cautioned against over-use due to their limited ability to metabolize/excrete salicylates. • Bismuth can cause stools to become black and tarry, resembling melena. • Shows up opaque on radiographs. • Animals dislike the taste. Refrigeration may help or use tablet form.

11. sulfasalazine (___________) • Sulfonamide antimicrobial that is chemically similar to a salicylate, producing an anti-inflammatory effect and decreasing GI secretions in the colon. • Use high doses with caution in cats due to salicylate. • Little effect as an antibacterial. • Sulfonamide antibiotics can cause keratoconjunctivitis sicca

12. AdsorbentsandProtectants -Many toxins/irritants cause hypersecretion and diarrhea by coming into direct contact with intestinal mucosal cells. An ADSORBENT will prevent this by adhering to the substance while a PROTECTANT will coat the gut wall like a blanket.

13. bismuth • Active ingredient in Pepto-Bismol and Kaopectate • Adsorbent of E. coli kaolin and pectin • Kaolin is a clay and pectin is a polysaccharide found in plant cell walls. • Combination acts as an adsorbent for bacteria and enterotoxins to bind to. • Found in OTC products but is not very effective at controlling diarrhea.

14. barium activated charcoal • Provides radiographic contrast. • Protectant that may also reduce chronic diarrhea after a contrast study is performed. • Adsorbent that has little effect on diarrhea. • Charcoal and toxin are excreted in the feces. • Messy! • Will not adsorb alcohol compounds, metals, or petroleum products