Procainamide Derivative- Metoclopramide *Reglan Blocks receptors in the CRTZ. Prokinetic drug: increases gastric contractions and speeds emptying, strengthens cardiac sphincter tone. DO NOT GIVE WITH GI OBSTRUCTION More effective in dogs than cats.

Antihistamines- Diphenhydramine *Benadryl, Dimenhydrinate *Dramamine 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 than cats. May cause sedation. Although injectables are available, oral dose can be given prophylactically.

Serotonin Receptor Antagonists- Ondansetron. Zofran, Dolasetron Serotonin Receptor Antagonists- Ondansetron *Zofran, Dolasetron *Anzemet 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 cytotoxic chemotherapy drugs Pricey, but may be worth it for short-term treatment.

NK-1 Receptor Antagonist- Maropitant citrate *Cerenia Inhibit the binding of Substance P (a neuropeptide) to neurokinin receptors in the Emetic center. 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.

ANTIDIARRHEALS Atropine, Aminopentamide, Propantheline Loperamide, Diphenoxylate Bismuth subsalicylate Sulfasalazine

Antidiarrheals change intestinal motility or reduce secretions. Diarrhea is the abnormal frequency and liquidity of fecal material due to failure of the intestinal tract to adequately absorb fluids from the intestinal contents. It is NOT a disease It IS a sign of disease It is a normal protective mechanism to remove substances from the GI tract. Antidiarrheals change intestinal motility or reduce secretions.

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

Anticholinergics- Atropine, Aminopentamide. Centrine, Propantheline Anticholinergics- Atropine, Aminopentamide *Centrine, Propantheline *Pro-Banthine Work against the effects of the neurotransmitter Acetylcholine. Also called parasympatholytics. Use with caution in animals who are already in Sympathetic mode (tachycardia, ileus) Most effective at reducing spastic contractions of the colon and diarrhea associated with tenesmus.

Opiod family- Loperamide *Immodium, Diphenoxylate *Lomotil Increase segmental contractions, decrease intestinal secretions, enhance intestinal absorption. Use with caution in cats and horses as they can cause CNS stimulation/excitement. Can cause constipation, ileus, sedation. May also mask GI pain. Atropine is often added to discourage abuse (will cause dry mouth). Lomotil is a Class V controlled substance, Immodium is OTC

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 listed on the previous slide are also in this category.

Bismuth subsalicylate *Pepto-Bismol, *Kaopectate Breaks down in the gut to bismuth carbonate and salicylate. Bismuth coats the mucosa, decreases secretions, and has an anti-bacterial effect, while salicylate (aspirin-like compound) decreases inflammation and secretions. Cats as they have 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.

Sulfasalazine *Azulfidine Sulfonamide antimicrobial that is chemically similar to a salicylate, producing an anti-inflammatory effect and decreasing GI secretions. Use with caution in cats. Little effect as an antibacterial.

ADSORBENTS/PROTECTANTS Bismuth Barium Kaolin Pectin -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.

Bismuth Barium Active ingredient in Pepto-Bismol and Kaopectate Protectant that also reduces GI secretions. Barium Provides radiographic contrast. Protectant that may also reduce chronic diarrhea.

Kaolin and pectin *Kaopectolin Activated Charcoal Adsorbent that has little effect on diarrhea. Decreases a toxin’s ability to be absorbed by the body. Charcoal and toxin are excreted in the feces. Messy! Kaolin and pectin *Kaopectolin 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. Do not give simultaneously with other oral medications. Improves vomiting and diarrhea.