Budesonide

Budesonide is a potent synthetic glucocorticoid that combines high topical anti-inflammatory activity with extensive (~80–90%) first-pass hepatic metabolism. The result is strong local efficacy in the airway, nasal mucosa, gut, or perianal tissue with markedly reduced systemic glucocorticoid exposure compared with prednisolone or dexamethasone — making it the corticosteroid of choice when local action without HPA-axis suppression is desired.

Mechanism of Action

• Glucocorticoid receptor binding: budesonide diffuses into cells and binds the cytosolic glucocorticoid receptor (NR3C1). The ligand-receptor complex translocates to the nucleus, where it modulates gene transcription via glucocorticoid response elements (GREs) and by tethering to other transcription factors.
• Anti-inflammatory effects (genomic, hours to days): induction of anti-inflammatory genes (e.g., IL-10, annexin A1/lipocortin-1), repression of pro-inflammatory transcription factors (NF-κB, AP-1), inhibition of phospholipase A2 (reducing arachidonic acid release and prostaglandin/leukotriene synthesis), and downregulation of cytokine, chemokine, and adhesion molecule expression.
• Cellular effects: inhibition of neutrophil apoptosis and demargination; promotion of eosinophil apoptosis; reduction of mast cell, basophil, and dendritic cell function; reduction of capillary permeability and tissue oedema.
• Dose-dependent immunosuppression: at higher cumulative systemic exposures, broader immune suppression and HPA-axis effects emerge — the rationale for site-targeted formulations that limit systemic bioavailability.

Pharmacokinetics (Differ Markedly by Formulation)

• Oral delayed/extended-release: 9–21% bioavailability; Tmax 2–8 h; AUC dose-proportional.
• Inhaled (DPI/pMDI): ~34% lung deposition; ~39% systemic bioavailability; Tmax ~10 min.
• Nebulised: ~6% systemic bioavailability.
• Nasal spray: very low systemic exposure.
• Volume of distribution: 2.2–3.9 L/kg.
• Protein binding: 85–90%.
• Metabolism: extensive first-pass via CYP3A (mainly CYP3A4) to 6β-hydroxybudesonide and 16α-hydroxyprednisolone — both with <1% of parent glucocorticoid activity.
• Half-life: 2–3.6 hours plasma; clinical effect outlasts plasma half-life due to receptor binding.
• Excretion: ~60% renal (as inactive metabolites). No unchanged drug recovered in urine.

Indications are formulation-specific. Below lists the major approved uses; check the relevant product for exact licensed indications in your jurisdiction.

Inhaled budesonide

• Asthma — maintenance treatment in adults and children; the SMART/MART strategy (fixed-dose budesonide/formoterol combination used both as maintenance and reliever) is recommended by GINA across step 1–5 in adolescents and adults.
• COPD — reduction of exacerbations in selected patients (typically as part of ICS-LABA or triple therapy).

Intranasal budesonide

• Seasonal and perennial allergic rhinitis; non-allergic rhinitis with eosinophilia; symptomatic relief of nasal polyposis.

Oral delayed/extended-release

• Crohn’s disease (mild-to-moderate, ileal or right-colonic) — induction and maintenance of remission.
• Ulcerative colitis (mild-to-moderate distal/extensive) — induction of remission.
• Eosinophilic oesophagitis (orodispersible tablets or oral suspension).
• IgA nephropathy at risk of rapid progression — targeted-release capsules delivering budesonide to the terminal ileum/Peyer’s patches to suppress mucosal IgA production.

Rectal foam / enema

• Mild-to-moderate distal ulcerative colitis (proctosigmoiditis).

• Hypersensitivity to budesonide or any of the excipients.
• Tuberculous, fungal, or untreated viral infections of the respiratory tract (for inhaled use) or relevant mucosa (for other routes).
• Local infection at the application site for rectal formulations (e.g., perianal abscess).
• Severe hepatic impairment (for oral systemic formulations — exposure markedly increased).

Common across formulations: headache, nasopharyngitis, upper respiratory tract infection.

Inhaled-specific: oropharyngeal candidiasis (thrush — counsel patients to rinse mouth and gargle after inhalation), dysphonia, throat irritation, cough.

Intranasal-specific: nasal irritation, epistaxis, sneezing, dryness; rare septal perforation with chronic high-dose use.

Oral systemic-specific (low but not zero with prolonged high doses): features of hypercorticism — moon facies, acne, easy bruising, weight gain, hypertension, hyperglycaemia, HPA-axis suppression, growth retardation in children, reduced bone mineral density.

Rectal-specific: anal irritation, abdominal discomfort.

Class effects with prolonged systemic exposure: cataract, glaucoma, osteoporosis, immunosuppression with infection risk, mood changes (insomnia, agitation), peripheral oedema.

• Strong CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, cobicistat, clarithromycin, grapefruit juice): substantially increase systemic budesonide exposure — avoid or use with caution; the effect is most clinically important for oral systemic formulations.
• Strong CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, phenobarbital, St John’s Wort): reduce budesonide exposure and may reduce efficacy.
• Other corticosteroids: additive systemic glucocorticoid load.
• Live vaccines: avoid during high-dose oral budesonide therapy; inhaled and topical formulations at standard doses generally do not preclude live vaccines.
• Drugs affecting potassium balance (loop and thiazide diuretics, amphotericin B, β2-agonists, theophylline): additive hypokalaemia risk with high-dose systemic glucocorticoids.

Dosing is highly formulation- and indication-specific. The summary below covers the principal regimens; refer to the relevant product label for full details.

Asthma (Inhaled DPI/pMDI)

• Adults and adolescents: 200–800 μg/day in 1–2 divided doses; up to 1,600 μg/day in severe disease.
• Children: 200–400 μg/day in 1–2 divided doses.
• Budesonide/formoterol MART: maintenance plus reliever doses as needed, up to manufacturer-specified maximum daily inhalations.

Asthma (Nebulised) — Children Unable to Use Inhalers

• 0.25–1 mg twice daily, titrated to control.

COPD (Inhaled, as Part of Combination Therapy)

• 320 μg twice daily within a fixed-dose combination, typically with formoterol ± glycopyrronium.

Allergic Rhinitis (Nasal Spray)

• Adults and children ≥6 years: 64–256 μg/day, divided as 1–2 sprays per nostril once or twice daily; titrate to the lowest effective dose.

Crohn’s Disease (Oral Delayed-Release Capsules)

• Induction (mild-to-moderate ileal/right-colonic disease): 9 mg once daily in the morning for up to 8 weeks.
• Maintenance: 6 mg once daily for up to 3 months; longer use balanced against systemic exposure.

Ulcerative Colitis (Oral Extended-Release Tablets / MMX)

• Induction: 9 mg once daily in the morning for up to 8 weeks.

Eosinophilic Oesophagitis (Orodispersible Tablet, Jorveza)

• Induction: 1 mg twice daily for 6–12 weeks.
• Maintenance: 0.5 mg twice daily.

IgA Nephropathy (Delayed-Release Capsules, Kinpeygo/Tarpeyo)

• 16 mg once daily in the morning for 9 months, followed by a 2-week taper.

Distal Ulcerative Colitis (Rectal Foam)

• 2 mg (one actuation) rectally once daily for 6–8 weeks.

Renal Impairment

No dose adjustment required for inhaled, nasal, or rectal formulations. Oral systemic formulations — limited data; standard dosing generally retained.

Hepatic Impairment

Mild-to-moderate: caution and monitor for systemic effects. Severe (Child-Pugh C): contraindicated for oral systemic formulations.

Missed Dose

Take as soon as remembered unless close to the next scheduled dose. Do not double up. For asthma reliever use within MART regimens, additional doses are taken on symptoms, not on missed scheduled doses.

HPA-Axis and Systemic Effects

Even non-systemic budesonide formulations can cause HPA suppression at high cumulative doses, in prolonged use, with concomitant CYP3A4 inhibitors, or in children. Periodically reassess the need for the lowest effective dose. Patients on prolonged high-dose therapy may require stress-dose corticosteroid cover for surgery, trauma, or severe illness, and should not abruptly stop after prolonged systemic use.

Oropharyngeal Candidiasis (Inhaled Formulations)

Rinse mouth, gargle, and spit after each inhalation. Spacer devices reduce oropharyngeal deposition. Treat thrush with topical antifungals as needed.

Growth in Children

Long-term inhaled corticosteroid use in children may reduce growth velocity. Use the lowest effective dose and monitor height regularly. Final adult height is generally not meaningfully affected at usual asthma doses.

Visual Disturbances

Patients reporting blurred vision or other visual symptoms should be evaluated for cataract, glaucoma, or rare conditions such as central serous chorioretinopathy.

Infections

Treat active infections appropriately. Avoid in patients with untreated tuberculosis or in close contact with measles or varicella when on high systemic doses.

Pregnancy and Lactation

• Pregnancy: inhaled and intranasal budesonide are first-line ICS choices in pregnancy with extensive safety data. Oral systemic formulations to be used only when clearly needed.
• Breastfeeding: budesonide is excreted in breast milk in very low amounts; inhaled and intranasal use is generally compatible.

Effect on Driving

No or negligible influence at standard doses.

Store below 30 °C in the original package to protect from moisture. Do not freeze nebuliser respules. Some pMDI products should not be exposed to temperatures above 50 °C (e.g., in a hot car).

Typically 2–3 years depending on formulation. After-opening windows differ — most DPIs and pMDIs are usable for 3–6 months after first opening; nebuliser respules must be used promptly after opening the protective envelope and any opened respule discarded after single use.

Prescription required for most formulations (Rx). Selected nasal spray strengths are available over the counter in some jurisdictions (e.g., the United States) but remain prescription-only in many EU markets.