Budesonide
Budesonide
Generic Name
Budesonide
Mechanism
- Glucocorticoid receptor (GR) activation: Binds intracellular GR, translocates to the nucleus, and modulates gene transcription.
- Inhibits pro‑inflammatory cytokines (IL‑5, IL‑13, TNF‑α) and reduces eosinophil recruitment.
- Promotes anti‑inflammatory protein synthesis (e.g., lipocortin‑1) → inhibits phospholipase A₂, ↓ leukotrienes, prostaglandins.
- Decreases mucosal permeability and leukocyte adhesion, reducing edema.
Pharmacokinetics
| Parameter | Value | Notes |
| Absorption |
• Oral: ~15 % bioavailability (first‑pass hepatic metabolism). • Inhaled: ~50 % systemic absorption from lungs. | Concentrated dose delivered directly to target tissue. |
| Distribution | Highly lipophilic; extensive intracellular tissue binding. | Rapid distribution to pulmonary and intestinal mucosa. |
| Metabolism | Liver CYP‑3A4 → inactive 6‑α‑O‑demethyl‑budesonide. | Enzymatic rival hepatotoxic interactions minimal. |
| Elimination | Urine (70 %), feces (30 %). | Half‑life ~2 h (lung); systemic ~8 h. |
| Drug interactions | CYP‑3A4 inhibitors ↑ systemic exposure; inhalation minimal overlap. | Avoid high‑dose systemic steroid concomitants. |
Indications
- Respiratory
- Moderate‑to‑severe asthma (inhalation therapy).
- Chronic obstructive pulmonary disease (COPD) – maintenance inhalation.
- Exacerbation of severe asthma (add‑on to systemic steroids).
- Gastro‑intestinal
- Ulcerative colitis (oral mesalamine‑type dose).
- Crohn’s disease (topical formulation for ileocolonic disease).
- IBS‑D (oral once‑daily dose).
- Others
- Laryngeal and nasal corticosteroid sprays for allergic rhinitis.
- Subcutaneous injections for severe inflammatory conditions (rare).
Contraindications
- Absolute Contraindication: Known hypersensitivity to budesonide or any excipient.
- Absolute Contraindication: Clinically significant systemic viral or bacterial infection, unless under physician supervision.
- Cautions
- Pregnancy: Category C; use only if potential benefit outweighs risk.
- Breastfeeding: Risk of neonatal adrenal suppression (rare).
- Glaucoma/Glaucoma‑susceptibility: Risk of ocular hypertension >10 mm Hg → ophthalmic exam before long‑term use.
- Hepatic impairment: Reduced clearance; use lower oral dose.
- Immunosuppressed patients: Potential for opportunistic infections.
Dosing
| Condition | Formulation | Dose | Frequency | Notes |
| Asthma (maintenance) | Inhaler (Budesonide 200 μg/puff) | 200–400 μg /day | BID | Use spacer if needed. |
| Asthma (exacerbation) | Inhaler (400 μg/puff) | 400 μg /day | TID for 5–7 days | Transition to maintenance after response. |
| COPD | Inhaler | 400 μg /day | BID | Prefer once‑daily formulations if available. |
| Ulcerative colitis (induction) | Oral tablets (2 mg) | 2–4 mg /day | BID | Follow with mesalamine if needed. |
| Crohn’s disease (topical) | Enema or suppository (1 mg) | 1 mg /day | BID | Localize to terminal ileum/colon. |
| IBS‑D | Oral tablets (0.5 mg) | 0.5 mg /day | QD | Adjunct to diet, fiber. |
| Allergic rhinitis | Nasal spray (50 μg/puff) | 50 μg /puff | BID | Use all 4 puffs. |
| Laryngeal | Nebulized solution (4 mg/mL) | 4 mg /dose | TID | Avoid if severe reflux. |
> Spacer use: Improves delivery efficiency and reduces oral deposition, lowering candidiasis risk.
Monitoring
- Pulmonary function tests (PFTs): Baseline and at 1, 3, 6 months for asthma/COPD patients.
- Bone density scan: Patients > 45 yrs or long‑term (>2 yrs) oral use.
- Ophthalmology exam: Baseline, annually if >6 mths usage.
- Serum cortisol/adrenal axis: Baseline and after 3 weeks of high oral dosing.
- Blood counts: Monitor for cytopenias in immunocompromised.
- Weight and growth: For pediatric use; assess quarterly.
Clinical Pearls
- Spacer–Asthma Equivalence: A spacer can halve the expected oral bioavailability, reducing systemic side effects without compromising lung deposition.
- “Double‑Dose” Misconception: Inhaled budesonide offers dose‑response only up to ~800 μg; higher doses frequently lead to local adverse effects.
- Oral vs. Inhaled: Oral budesonide has a markedly higher first‑pass effect; use only when not feasible (e.g., active ulcerative colitis).
- Nasal Spray Award: Budesonide nasal spray is the only steroid approved specifically for acute allergic rhinitis flare‑ups (within 12 h of exposure).
- Pediatric Growth Concerns: A weight‑based dose of 0.5 mg/day maintains efficacy while minimizing growth retardation; adjust upward only if uncontrolled symptoms persist.
- Drug‑Drug Interaction Awareness: Strong CYP‑3A4 inhibitors (e.g., ketoconazole, clarithromycin) can raise oral budesonide levels up to 3‑fold; lower dose or monitor for Cushingoid features.
- Expired Formulations? Ignore the “expired” labelling for inhaled budesonide – if the solution is clear and odorless, usage remains safe for up to 30 days after expiration if stored correctly.
Take‑away: Budesonide is a high‑potency, low‑systemic‑load steroid ideal for targeted mucosal inflammation. Proper inhaler technique, spacer use, and routine monitoring keep patients safe and effective.