Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Overview
Budesonide (Entocort EC®, Uceris®) is an orally administered, locally active glucocorticoid used primarily in dogs and cats for the management of chronic inflammatory enteropathies. It is designed to exert potent anti-inflammatory effects within the gastrointestinal tract while undergoing extensive first-pass hepatic metabolism, thereby reducing—but not eliminating—systemic glucocorticoid exposure.
In veterinary medicine, budesonide has been used as an alternative to systemic corticosteroids in patients that are intolerant of traditional agents such as prednisone. Clinical studies in dogs with chronic inflammatory enteropathies have demonstrated modest improvement in clinical and/or histopathologic parameters. Anecdotal reports suggest benefit in some cats with similar conditions.
Mechanism of Action (MOA): Budesonide is a potent glucocorticoid (approximately 15 times more potent than prednisolone) with high topical activity and weak mineralocorticoid effects. Enteric-coated formulations delay dissolution until the drug reaches the small intestine, allowing targeted local anti-inflammatory action. Although absorbed into the portal circulation, extensive hepatic first-pass metabolism limits systemic bioavailability; however, hypothalamic-pituitary-adrenal (HPA) axis suppression has been documented in dogs and cats.
Indications
In dogs and cats, budesonide is used primarily for the management of chronic inflammatory gastrointestinal diseases, particularly in patients that are intolerant of or poorly controlled with traditional systemic glucocorticoids.
- Chronic inflammatory enteropathies (dogs): Used for management of chronic inflammatory bowel disease (IBD) and related enteropathies. Clinical studies have shown modest improvement in clinical signs and/or histopathologic findings compared with placebo.
- Steroid-intolerant patients (dogs and cats): Considered in patients experiencing unacceptable adverse effects from systemic corticosteroids, although evidence supporting fewer systemic adverse effects is limited.
- Chronic inflammatory enteropathies (cats): Anecdotally reported to be beneficial in some cats with chronic gastrointestinal inflammation.
- Feline asthma (inhaled form): Inhaled budesonide has been reported to improve clinical signs in cats with asthma or chronic bronchitis; however, commercially available inhalation devices may limit practical use.
Dosage (Reference)
Dog
In dogs, budesonide is most commonly administered orally for chronic inflammatory enteropathies. Dosing is typically based on body size rather than strictly on mg/kg calculations.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| Chronic inflammatory enteropathies | PO | Small dogs: 1 mg once daily Large/Giant dogs: up to 3 mg every 12–24 hours |
Total dose should probably not exceed 3 mg every 12 hours. |
| Inhaled therapy | Inhalation | No dosing information available | Commercial inhaler devices may limit veterinary use. |
• Do not crush or chew enteric-coated capsules.
• HPA axis suppression has been documented even with oral formulations.
• Consider stress-dose steroid supplementation during major procedures if long-term therapy has been used.
Cat
In cats, budesonide is used orally for chronic inflammatory enteropathies and may also be administered by inhalation for asthma.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| Chronic inflammatory enteropathies | PO | Total dose should probably not exceed 1 mg every 8 hours | Use caution with long-term administration. |
| Feline asthma (inhaled) | Inhalation | 400 µg every 12 hours | HPA axis suppression has been reported with inhaled use. |
• Capsules intended for human use may require compounding to achieve appropriate feline doses.
• Do not alter or damage enteric-coated microspheres if reformulating capsules.
• Monitor for signs of systemic glucocorticoid effects with prolonged use.
Warnings & Precautions
Although budesonide is formulated to minimize systemic glucocorticoid exposure, clinically relevant systemic effects can still occur. Careful patient selection and monitoring are required in dogs and cats receiving this medication.
- Hypersensitivity: Contraindicated in patients with known hypersensitivity to budesonide.
- Systemic glucocorticoid effects: Despite high first-pass hepatic metabolism, systemic corticosteroid effects—including hypothalamic-pituitary-adrenal (HPA) axis suppression—have been documented in dogs and cats.
- Conditions affected by corticosteroids: Use cautiously in patients with gastrointestinal ulceration, active infections, diabetes mellitus, or cataracts, as glucocorticoids may exacerbate these conditions.
- Hepatic impairment: Risk of increased systemic exposure may be present in patients with liver dysfunction; dosage reduction may be necessary.
- Stressful events: Because HPA axis suppression may occur, supplemental exogenous corticosteroids should be considered for animals undergoing surgery or other major stressors.
- Pregnancy: Budesonide has demonstrated embryocidal and teratogenic effects in laboratory species; use only when potential maternal benefits outweigh fetal risks.
- Nursing animals: Specific data in veterinary species are lacking; use cautiously, weighing potential risks and benefits.
Drug Interactions
Budesonide is extensively metabolized by hepatic CYP3A enzymes and may also increase the risk of gastrointestinal injury when combined with other ulcerogenic medications. When used in dogs and cats, concurrent drug therapy should be reviewed carefully.
- Aspirin: Increased risk of gastrointestinal erosion, ulceration, or perforation when used concurrently.
- NSAIDs (e.g., carprofen, meloxicam, robenacoxib): Additive risk of GI erosion, ulceration, or perforation.
- Oral antacids: Because dissolution of enteric-coated formulations is pH dependent, separate administration by at least 2 hours.
- CYP3A inhibitors: Drugs that inhibit CYP3A may significantly increase systemic exposure to budesonide. Reported or theoretical examples include:
• Azole antifungals (e.g., fluconazole, itraconazole, ketoconazole)
• Cimetidine
• Cyclosporine
• Diltiazem
• Erythromycin
• Grapefruit juice products
Side Effects & Overdose
Side Effects
Although budesonide is formulated to reduce systemic exposure, clinically relevant glucocorticoid adverse effects may still occur in dogs and cats, particularly with prolonged use or higher doses.
- HPA axis suppression: Documented in dogs and cats receiving oral or inhaled formulations.
- Systemic glucocorticoid effects: Increased appetite, thirst, urination, panting, lethargy, muscle weakness, weight gain, abdominal distention, and coat or skin changes may occur, especially with long-term use.
- Hepatic enzyme elevations: Increases in liver enzyme activity have been reported in some dogs.
- Gastrointestinal injury: Because budesonide is a potent locally active glucocorticoid, overdosing may increase the risk of GI erosion, ulceration, or even perforation.
Overdose
Acute overdoses of glucocorticoids used alone are unlikely to result in life-threatening effects; however, gastrointestinal signs can occur in dogs and cats. Chronic excessive dosing increases the risk of significant systemic corticosteroid adverse effects.
- Clinical signs: Gastrointestinal upset (vomiting, diarrhea), lethargy, and signs consistent with glucocorticoid excess.
- Chronic overexposure: May result in pronounced systemic corticosteroid effects and persistent HPA axis suppression.
- Management: Provide supportive care as needed and monitor for GI injury and endocrine complications. Consultation with a veterinary poison resource is recommended in suspected significant overdose.
Key Notes
Practical clinical considerations for the use of budesonide in dogs and cats:
- Size-based dosing in dogs: Dosing is commonly based on patient size rather than strict mg/kg calculations, simplifying administration in clinical practice.
- Delayed-release formulation: Enteric-coated capsules are designed to dissolve at higher intestinal pH, targeting delivery to the small intestine.
- Bioavailability considerations: Oral bioavailability in dogs is approximately 10%–20% due to extensive first-pass metabolism.
- Withdrawal strategy: Avoid abrupt discontinuation after prolonged therapy; gradual tapering may be appropriate depending on duration of treatment.
- Compounding caution: If reformulating capsules into smaller doses, the enteric-coated microspheres should not be crushed or damaged.
- Intradermal allergy testing: Inhaled budesonide may reduce skin test reactivity; consider an appropriate withdrawal period before intradermal skin testing.
