Budesonide

Budesonide is a potent glucocorticoid used orally in veterinary medicine mainly for selected chronic inflammatory enteropathies. Its therapeutic concept is strong local anti-inflammatory activity within the gut with extensive hepatic first-pass metabolism of absorbed drug. This can reduce systemic exposure compared with an equivalent systemic glucocorticoid effect, but does not eliminate it.

Release characteristics differ between formulations, so the part of the intestine exposed to active drug is clinically relevant. Budesonide can still cause systemic corticosteroid effects and suppression of the hypothalamic–pituitary–adrenal axis; it is not intrinsically confined to the bowel.

Group

Locally acting glucocorticoid

Mechanism of Action

Budesonide binds intracellular glucocorticoid receptors in intestinal and other exposed cells. The receptor complex modifies gene transcription, reducing inflammatory mediator production and immune-cell activity. This suppresses mucosal inflammation rather than directly eradicating an infectious agent or correcting every cause of malabsorption.

Enteric coatings and controlled-release matrices delay or distribute release according to luminal conditions, influencing where the drug becomes available. Formulation-specific release patterns determine local intestinal exposure and the amount subsequently absorbed.

Absorbed budesonide undergoes extensive first-pass hepatic metabolism, limiting the amount reaching systemic circulation. Nevertheless, sufficient active drug can escape to cause glucocorticoid effects, and altered hepatic function can increase systemic exposure. Local accumulation and receptor potency contribute to clinical activity even when plasma concentrations are relatively low.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Inflammatory enteropathy	0.12–0.15 mg/kg	PO	Every 8–12 h	The interval may be extended to 24 hours when improvement is established.
Inflammatory enteropathy	3 mg/animal	PO	Every 24 h	Alternative using an intact 3 mg capsule; select according to patient size and response.
Inflammatory enteropathy	1 mg/animal	PO	Every 24 h	Small-dog fixed-dose alternative; exact weight boundaries are not assigned.
Inflammatory enteropathy	2 mg/animal	PO	Every 24 h	Large-dog fixed-dose alternative; exact weight boundaries are not assigned.
Surface-area inflammatory enteropathy treatment	Reference only	PO		3 mg/m² orally once daily or every other day; explicitly not 3 mg/kg. Surface-area calculation is unsupported.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Inflammatory enteropathy	0.12–0.15 mg/kg	PO	Every 8–12 h	The interval may be extended to 24 hours when improvement is established.
Inflammatory enteropathy	0.5–0.75 mg/animal	PO	Every 24 h	Requires an appropriately reformulated oral preparation.
Inflammatory enteropathy	1 mg/animal	PO	Every 24 h
Inflammatory enteropathy	1 mg/animal	PO	Every 12–24 h

Indications

Selected canine chronic inflammatory enteropathy or inflammatory bowel disease requiring glucocorticoid treatment.
Canine colitis when the formulation provides an appropriate intestinal release pattern.
Selected feline inflammatory bowel disease, including situations where another systemic glucocorticoid is poorly tolerated.

Contraindications

Use cautiously in patients in whom systemic corticosteroid exposure is undesirable.
Budesonide hypersensitivity; use cautiously with active infection, diabetes, gastrointestinal ulcers or cataracts.

Interactions

CYP450 inhibitors may increase systemic exposure.
CYP3A inhibitors including azole antifungals, macrolides, cimetidine and diltiazem can markedly increase systemic steroid exposure.
Do not give oral antacids simultaneously with pH-dependent enteric products. Effects of other acid-suppressive medicines depend on the formulation; avoid assuming that all enteric-release products behave identically.

Adverse effects

Adrenal suppression
Elevation of liver enzymes
Other systemic corticosteroid effects

Preparations

Preparation	Form	Strength	Route
Budesonide 3 mg enteric capsule Do not crush; enteric release differs from extended-release tablets.	Capsule	3 mg / capsule	PO
Budesonide 6 mg tablet Extended-release presentation; not interchangeable with conventional enteric capsules.	Tablet	6 mg / tablet	PO
Budesonide 9 mg tablet Extended-release presentation; not interchangeable with conventional enteric capsules.	Tablet	9 mg / tablet	PO

Monitoring and Administration

Monitor clinical response, liver enzymes and adrenal suppression during prolonged treatment.

Do not crush enteric-coated capsules or compound their contents unless proximal intestinal release is specifically intended.

The described dog size-based alternatives are 1 mg daily at 3–7 kg, 2 mg at 7–15 kg, 3 mg at 15–30 kg and 5 mg above 30 kg. Boundaries overlap in the source, so these are not encoded as product weight bands.

When reformulating into smaller capsules, preserve the enteric-coated internal spheres; damaging them changes the site of release.