Budesonide
Budesonide is a potent, locally acting corticosteroid (strong glucocorticoid, weak mineralocorticoid). In humans, the enteric coated oral form is used to treat or to manage Crohn's Disease and the inhaled formulations are used to manage asthma and allergies. Because of its low systemic bioavailability and high first-pass hepatic metabolism, it is regarded as a "topical" corticosteroid at the site of delivery. In large-scale clinical trials in humans with mild to moderate Crohn's Disease, budesonide was well tolerated with fewer corticosteroid-related adverse effects than prednisolone. The presence of food in the GI tract will affect the speed but not the amount of the drug that is absorbed.
Dogs and Cats
IBD is a common problem and a diagnostic challenge in small animal practice. It is seen in both dogs and cats, although the presentation is somewhat different. The diagnosis of IBD is based on histologic evidence of inflammation in the intestine. Further classification is based on the affected region of the intestine and the predominant cell type in the infiltrate. Diagnostic tests include CBC, chemistry, fecal cytology and parasitology, urinalysis, abdominal radiograph and ultrasound and, ultimately, intestinal biopsy. There are some breeds including Basenjis, Wheaten Terriers, Boxers and Norwegian Lundehunds with an increased incidence of specific forms of IBD. Animals rarely are cured of IBD unless a specific underlying cause (such as parasitism) is determined and, more commonly, the goal of therapy is to control clinical signs with the minimum amount of drugs. The majority (85%) of cats with IBD respond favorably to corticosteroid therapy.
Budesonide is a newer corticosteroid that, in some instances, can replace prednisone or prednisolone for immunosuppression therapy. Although research has demonstrated hypothalamopituitary-adrenal suppression in normal dogs receiving budesonide, many side-effects associated with long-term corticosteroid therapy were not as apparent.
The human budesonide product is enteric coated; non-enteric-coated formulations may be preferable in small animals because the location of IBD tends to be more proximal within the GI tract in dogs and cats.
Budesonide Side Effects
Although corticosteroid-related side effects are less common with budesonide, they include polyuria, polydipsia, increased appetite and changes in hair coat.
Precautions
- Budesonide should be used with caution in animals with decreased liver function.
- Because budesonide is a corticosteroid, it should be used with additional caution in animals with GI ulceration, active infection, diabetes or cataracts. Additional corticosteroid supplementation may be needed for budesonide treated animals undergoing surgery.
- There has been positive research in humans on the use of budesonide during pregnancy for women with Crohn's Disease. The FDA considers budesonide a Category C drug.
Drug Interactions
- Budesonide should not be used concomitantly with erythromycin, cimetidine, ketoconazole, itraconazole, fluconazole, and diltiazem. Budesonide is metabolized by a hepatic enzyme (CYP3A), which is inhibited by these drugs.
- Oral antacids will dissolve the enteric coating of budesonide. Simultaneous dosing with omeprazole has been studied in humans and does not affect the pharmacokinetics of budesonide.
Overdose
Experimentally, massive (100x) overdose was lethal in mice. In the event of overdose, prompt gut-evacuation may be indicated.
