procainamide derivative- metoclopramide *reglan blocks receptors in the crtz. prokinetic drug:...

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

*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,

DiphenoxylateBismuth subsalicylate

Sulfasalazine

• 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

*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

-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.

BismuthBarium

KaolinPectin

Bismuth• Active ingredient in Pepto-Bismol and Kaopectate

• Protectant that also reduces GI secretions.

Barium• Provides radiographic contrast.

• Protectant that may also reduce chronic diarrhea.

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.