Oral GI protectants and adsorbents

Oral protectants and adsorbents work locally within the GI tract either by coating inflamed mucosa with a protective layer or by binding bacteria, toxins, and digestive juices and, thus, preventing mucosal damage and systemic absorption. Adsorbents lack specificity and may prevent drug absorption as well. The most commonly used drugs in this category are bismuth subsalicylate (Pepto-Bismol—Procter & Gamble) and kaolin-pectin (Kaopectate—Pharmacia).

The old formulation of Kaopectate contained only kaolin and pectin, while later formulations contain attapulgite. These substances change the consistency of the feces but have no effect on fluid or electrolyte loss. All three of these substances are safe for cats as they are not absorbed into the bloodstream. Recently, Kaopectate was reformulated to contain bismuth subsalicylate. Bismuth subsalicylate has antibacterial, antienterotoxin, and anti-inflammatory properties. Exercise caution when using this drug because salicylate compounds are slowly eliminated in cats if systemic absorption occurs. Bismuth subsalicylate can be used in cats at a dose of 0.5 to 1 ml/kg orally every 12 hours for no longer than two or three days.²⁸ Cats strongly resist the taste of this medication, and its use may produce green-black stools resembling melena.

Motility modifiers increase GI transit time, thereby allowing more water reabsorption from the luminal contents. These drugs may be indicated if fluid losses are high, fluid replacement is not sufficient to maintain adequate hydration, and the diarrhea is intractable. Motility modifiers are contraindicated in patients with infectious diarrhea because they may increase absorption of bacterial toxins.

Centrine (Pfizer Animal Health) is an antispasmodic and anticholinergic agent whose active ingredient is aminopentamide hydrogen sulfate. It is commonly used to treat diarrhea, abdominal visceral spasm, vomiting, and gastritis in dogs and cats. The dose for cats is 0.1 mg orally every eight to 12 hours.²⁹ Adverse effects include dry eyes and mouth, inability to urinate, difficulty swallowing, vomiting, constipation, sedation or excitement, staggering, seizures, enlarged pupils, and abnormal heart rhythms; death may also occur.²⁹

Cats can also be given diphenoxylate hydrochloride³⁰ (1.25 mg orally every 12 hours) or loperamide hydrochloride (0.04 to 0.06 mg/kg orally every 12 hours).³¹ However, we think that these drugs are rarely appropriate in feline patients and can cause adverse reactions, including respiratory depression and excitatory behavior.

CONCLUSION

Chronic diarrhea doesn't resolve overnight. Even with a specific diagnosis, diarrhea may not resolve with targeted pharmacologic therapy alone. Dietary, prebiotic, and probiotic therapy are important complementary options and may serve as sole therapy in some patients with nonspecific disease. A multimodal approach often produces the best chance for clinical improvement.

Sally Purcell, DVM
Audrey K. Cook, BVM&S, MRCVS, DACVIM, DECVIM-CA
Department of Small Animal Clinical Sciences
College of Veterinary Medicine
Texas A&M University College Station, TX 77843-4474