Budesonide
Budesonide is a corticosteroid used as inhaled therapy in asthma and chronic obstructive pulmonary disease, as nasal spray in allergic rhinitis, and in extended-release oral formulations for inflammatory bowel disease, with limited systemic exposure.
- Chemical formula
- C25H34O6
- CAS number
- 51333-22-3
- ATC code
- R03BA02
- Molecular weight
- 430.53 g/mol
- Drug class
- Inhaled corticosteroid
- Also known as
- Budesonida
What is it?
Budesonide is a synthetic glucocorticoid with high topical anti-inflammatory potency and limited systemic activity due to extensive first-pass hepatic metabolism. It is supplied as inhalation aerosol, nebuliser solution, dry powder inhaler, nasal spray, and as extended-release oral capsules and tablets for inflammatory bowel disease. The molecule is dispensed only on prescription in most markets and is widely used because of its favourable topical-to-systemic effect ratio.
Mechanism of action
Budesonide binds intracellular glucocorticoid receptors and modulates gene transcription, decreasing the synthesis of proinflammatory cytokines, chemokines and adhesion molecules and reducing the recruitment of inflammatory cells. In the airway it suppresses chronic inflammation that underlies asthma and COPD; in the bowel it acts on the mucosa with limited systemic absorption. Onset of clinical effect is gradual, requiring days to weeks of regular use for full benefit.
Pharmacokinetics
After inhalation, a small fraction of the dose reaches systemic circulation; oral bioavailability is only about 10% to 13% due to extensive first-pass metabolism, mainly by CYP3A4. Plasma protein binding is approximately 85% to 90%. The terminal half-life is two to three hours. Hepatic impairment and strong CYP3A4 inhibitors substantially increase systemic exposure and the risk of corticosteroid effects. Locally acting oral formulations rely on the same first-pass metabolism to limit systemic absorption.
Indications
Budesonide is approved as maintenance therapy in asthma and COPD as inhaled corticosteroid; as topical nasal therapy in allergic rhinitis and nasal polyps; and in extended-release oral formulations for the induction and maintenance of remission in mild to moderate Crohn's disease and microscopic colitis. According to international guidelines, inhaled budesonide is one of the recommended controllers in asthma, often as part of combination inhalers.
Safety profile
Local adverse effects include oral candidiasis, dysphonia and pharyngeal irritation, mostly preventable by mouth rinsing after use. Systemic corticosteroid effects are uncommon at recommended doses but can occur with high-dose long-term inhaled use, with strong CYP3A4 inhibitors or with the oral formulations. Adrenal suppression, growth slowing in children, glucose changes and bone effects should be monitored. According to the prescribing information, regular review of dose and technique by a clinician is essential.
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Frequently asked questions
How does inhaled budesonide compare with oral corticosteroids? ▾
Inhaled budesonide delivers the corticosteroid directly to the airway with much lower systemic absorption than oral therapy at equivalent topical effect. This typically reduces the systemic adverse-effect burden such as weight gain, glucose changes and bone effects. According to international guidelines, inhaled corticosteroids are the cornerstone of asthma maintenance, while oral corticosteroids are reserved for short courses in exacerbations or selected severe disease.
Why rinse the mouth after using a budesonide inhaler? ▾
Rinsing the mouth and gargling with water after each inhaled corticosteroid dose reduces the risk of local adverse effects, particularly oral candidiasis (thrush) and dysphonia. Use of a spacer also reduces deposition in the mouth and pharynx. According to the prescribing information, these simple measures should be reviewed by the clinician or pharmacist as part of inhaler technique training, alongside dose timing and storage.
Can children use inhaled budesonide? ▾
Yes. Inhaled budesonide is widely used in children with asthma, including via nebulisers in young children. According to international guidelines and the prescribing information, paediatric dosing is age-based and should always be reviewed by a paediatrician. Growth velocity may be slightly reduced at higher doses, particularly in pre-pubertal children, and should be monitored periodically by the prescriber.
How is oral budesonide for bowel disease different from inhaled? ▾
Oral budesonide formulations for Crohn's disease or microscopic colitis are designed to release the drug along the small or large bowel mucosa, with most of the absorbed dose extracted by the liver during first-pass metabolism. This gives a topical effect on the mucosa with limited systemic exposure, although it is greater than that of the inhaled formulation. According to the prescribing information, the duration of treatment is usually limited.
What are the main contraindications for budesonide? ▾
Budesonide is contraindicated in known hypersensitivity to the molecule or its excipients. Caution is required in active untreated infection, particularly tuberculosis, in severe hepatic impairment, in children for long-term high-dose inhaled use, and in pregnancy and breastfeeding, where benefits and risks should be reviewed. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
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