Misoprostol

Uses & side effects

Treatment of ulcers

Product-specific side effects await source review.

Drug interactions

Misoprostol (Cytotec®) is an FDA-approved drug used in humans to prevent or treat gastric ulcers caused by NSAIDs. [2]

In horses, it is used off-label to prevent NSAID-induced hindgut issues such as colitis or hindgut ulcers. In addition, it can be used to treat gastric ulcers in the stomach’s glandular region.

Misoprostol is a synthetic prostaglandin E1 analogue that acts as a cytoprotectant, protecting cells from damage. [9] This drug can reduce inflammation in the gut and help ease some of the associated discomforts.

It has been shown to reduce the secretion of gastric acid in the stomach of horses. [13] Excessive acidity contributes to the formation of ulcers by eroding cells that line the intestinal tract.

Misoprostol has also been shown to improve intestinal barrier function in the gut of horses on NSAID medications. It helps to support the healing of the gastrointestinal mucosa following injury. [32]

Effects of NSAIDs
Pain-relieving NSAID medications – such as flunixin meglumine (banamine), and phenylbutazone (bute) – inhibit the enzyme cyclooxygenase-1 (COX-1). This enzyme is involved in pathways that activate inflammation following injury or infections.

In particular, the COX-1 enzymes make molecules called prostaglandins and thromboxane, which are involved in activating the immune system and causing a pain response.

Blocking COX-1 with NSAIDs is an effective way to relieve pain, inflammation and fever, which is why these drugs are commonly prescribed for horses with colic, arthritis or laminitis. Long-term use of NSAIDs may be required to provide comfort and improve the quality of life for these horses.

Prostaglandins and Gut Health
However, prostaglandins are also important for protecting cells of the digestive tract. The digestive tract is lined with a mucous barrier known as the mucosa. This blocks bacteria and toxins from being absorbed while allowing nutrients to pass into the blood.

Prostaglandins are involved in maintaining this defensive mucosal barrier and have several effects on the digestive tract, including: [3][4][5][6]

Increase blood flow in the mucosa by causing blood vessels to dilate
Raise mucosal bicarbonate secretion which helps to neutralize stomach acid
Decrease stomach acid production
Modulate immune responses
NSAIDs and Gut Injury
By blocking COX-1, NSAIDs suppress prostaglandin production, which compromises the mucosa’s ability to form a protective barrier between the environment inside the digestive tract and the cells lining it.

This allows stomach acidity and other irritants to cause inflammation, ulcers and bleeding throughout the gut.

In addition, NSAIDs will slow the recovery of pre-existing lesions by causing neutrophils to gather at the injury and exacerbate inflammation. [7][8]

COX-2-specific NSAIDs such as Equioxx and Previcox have been developed to lessen the digestive side effects of NSAID use. However, their long-term use may still induce injury in the small and large intestines. [31]

Ideally NSAIDs should be avoided in horses with pre-existing ulcers in the gastrointestinal tract. However, these horses may develop conditions such as laminitis which require treatment with NSAIDs. Misoprostol may be administered concurrently with the NSAIDs to help prevent ulcers from worsening. [7]7) Marshall, J. F. et al. The effect of

Contraindications