Budesonide is a synthetic glucocorticoid with potent anti-inflammatory and immunosuppressive properties. Its mechanism involves:

1. Binding to Glucocorticoid Receptors: Enters target cells and binds to intracellular receptors, modulating gene expression.
2. Inhibition of Inflammatory Mediators: Suppresses phospholipase A2, reducing prostaglandin and leukotriene synthesis (Lippincott).
3. Immune Cell Suppression: Inhibits cytokine release (e.g., IL-1, TNF-α) and reduces eosinophil, mast cell, and lymphocyte activity.
4. Localized Action: Designed for high topical potency with minimal systemic absorption, making it ideal for inhaled, nasal, and enteric formulations.

Budesonide is approved for:

1. Respiratory Diseases:
   • Asthma: Maintenance therapy via inhaler (often combined with formoterol in Symbicort®).
   • Chronic Obstructive Pulmonary Disease (COPD): Reduces exacerbations.
   • Allergic Rhinitis: Nasal spray (e.g., Rhinocort®).
2. Gastrointestinal Disorders:
   • Crohn’s Disease: Enteric-coated tablets (e.g., Entocort®) for ileal and ascending colon inflammation.
   • Eosinophilic Esophagitis: Off-label use.
3. Dermatological Conditions:
   • Topical cream for eczema and inflammatory skin disorders.
4. Croup in Children: Nebulized budesonide as an alternative to dexamethasone.

Adults:

• Asthma/COPD (Inhalation): 200–800 mcg twice daily (BNF).
• Allergic Rhinitis (Nasal): 100–200 mcg per nostril once daily.
• Crohn’s Disease (Oral): 9 mg once daily in the morning for up to 8 weeks; taper to 6 mg for maintenance.

Children:

• Asthma (≥6 years): 100–400 mcg twice daily via inhaler.
• Croup (Nebulized): 2 mg single dose.

Special Populations:

• Renal/Hepatic Impairment: No dose adjustment required for inhalation/nasal routes. Use oral forms cautiously in severe liver disease.
• Pregnancy: Category C; use lowest effective dose (BNF).
• Elderly: Monitor for systemic effects (e.g., osteoporosis).

• Local Effects:
  • Inhaled/Nasal: Oral thrush, hoarseness, epistaxis, nasal irritation.
  • Oral: Dyspepsia, nausea.
• Systemic Effects (rare with topical use):
  • Adrenal suppression, hyperglycemia, osteoporosis, growth retardation (children).
  • Mood changes, insomnia, glaucoma, cataracts (long-term use).

1. Contraindications: Hypersensitivity to corticosteroids, systemic fungal infections.
2. Infections: Avoid in active tuberculosis or untreated bacterial/viral infections.
3. Monitoring:
   • Adrenal Function: For long-term/high-dose therapy.
   • Bone Density: In patients at risk for osteoporosis.
   • Growth: In pediatric patients.
4. Withdrawal: Taper gradually to avoid adrenal crisis.

• CYP3A4 Inhibitors (e.g., ketoconazole, ritonavir): Increase budesonide levels (avoid combination or reduce dose).
• NSAIDs: Increased gastrointestinal ulcer risk.
• Vaccines: Avoid live vaccines (e.g., MMR, varicella) due to immunosuppression.
• Diuretics: Enhanced hypokalemia risk.

• Generic: Budesonide.
• Brand Names:
  • Inhaler: Pulmicort®, Symbicort® (with formoterol).
  • Nasal: Rhinocort®.
  • Oral: Entocort®.
  • Topical: Cortifoam®, Budesonide cream.