Symbicort
Symbicort
Generic Name
Symbicort
Mechanism
- Budesonide binds intracellular glucocorticoid receptors → ↑ trans‑activation of anti‑inflammatory genes, ↓ pro‑inflammatory cytokines (IL‑5, TNF‑α, IFN‑γ).
- Formoterol competitively activates β₂‑adrenergic receptors on airway smooth muscle → Gs protein ↑ cAMP → protein kinase A → smooth‑muscle relaxation and bronchodilation.
- The dual action suppresses airway inflammation and provides prolonged bronchodilation (onset ~5 min, duration 12‑14 hrs).
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Pharmacokinetics
| Parameter | Data |
| Absorption | Rapid pulmonary deposition; systemic absorption ~15–20 % after inhalation. |
| Distribution | Budesonide: 4.8 L/kg; Formoterol: 1.4 L/kg. |
| Metabolism | Budesonide → glucuronidation (UGT‑2B7) → inactive metabolites. Formoterol → hydroxylation (CYP3A4/5) → inactive. |
| Elimination | Budesonide: 80 % renal excretion; Formoterol: 60 % renal, 25 % biliary. |
| Half‑life | Budesonide ~7–8 h (pulmonary); Formoterol ~14 h (systemic). |
| Peak plasma concentration | 5–10 min post‑inhalation. |
| Drug‑drug interactions | Moderately ↑ systemic β₂ agonist effect with beta‑blockers; CYP3A4 inhibitors moderately increase formoterol exposure. |
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Indications
- Asthma – maintenance treatment to reduce exacerbations, improve lung function, and control symptoms.
- Chronic Obstructive Pulmonary Disease (COPD) – maintenance therapy to decrease exacerbations and improve airflow.
- Large‑airways obstruction in patients unable to use rescue inhalers alone.
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Contraindications
- Contraindications
- Severe hypersensitivity to budesonide, formoterol, or any excipient.
- Unsuitable for use as rescue medication (cannot provide rapid symptom relief).
- Warnings
- Cardiovascular: β₂‑agonist may cause tachycardia, tremor, palpitations. Avoid if isolated heart block or severe arrhythmia without a cardio‑selective β₂ agonist.
- Eye pressure: rarely increases IOP; caution in glaucoma.
- Growth suppression: possible decrease in linear growth in pediatric patients; dose optimization recommended.
- Systemic effects: risk of Cushingoid features with systemic absorption; avoid concomitant oral steroids at higher doses.
- Pregnancy & Lactation: Category C; local effects minimal but monitoring recommended.
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Dosing
| Indication | Typical Dose | Administration Frequency | Notes |
| Asthma (maintenance) | 2–4 puffs BID (total daily 400–800 µg budesonide + 12–24 µg formoterol) | Twice daily | Start at 2 puffs BID, titrate up per response. |
| COPD (maintenance) | 2–4 puffs BID | Twice daily | Similar titration; monitor FEV₁. |
| Pediatric (≥6 yr) | 1–2 puffs BID | Twice daily | Half adult dose for 6–12 y, full adult dose for 13–18 y; adjust per growth. |
• Use rinse: After use, rinse mouth and spit to reduce oral candidiasis risk.
• Reconstitution: No liquid reconstitution required.
• Device instructions: Shake well before each puff; dose indicator guides remaining doses.
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Adverse Effects
| Category | Examples |
| Common |
• Headache, insomnia, dry mouth, nausea. • Local thrush, oral erythema (use mouth rinse). • Palpitations or tremor (β₂‑agonist). |
| Serious |
• Systemic steroid effects: Cushingoid features, adrenal suppression. • Cardiovascular events: tachycardia, hypertension, arrhythmias. • Hypersensitivity reaction, anaphylaxis (rare). • Osteoporosis with long‑term use (>6 mo). |
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Monitoring
- Pulmonary function: FEV₁, peak expiratory flow (PEF) every 4–6 weeks.
- Growth: Height velocity in pediatric patients.
- Blood pressure & heart rate: Monitor for β₂‑agonist side effects.
- Glucose: Check baseline/follow‑up if risk for steroid‑induced hyperglycemia.
- Respiratory status: Exacerbation frequency, rescue inhaler use.
- Corticosteroid‑related labs: Serum cortisol, HPA axis function if prolonged systemic exposure suspected.
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Clinical Pearls
- Synergistic dosing: Because budesonide and formoterol mechanistically complement each other, the combination allows lower systemic steroid exposure than equivalent oral regimens.
- Device technique matters: Inadequate inhaler technique (e.g., low‑force inhalation) reduces drug deposition; teach and re‑teach technique every visit.
- Efficacy in COPD: Symbicort improves FEV₁ and reduces exacerbations more markedly when used in patients with a history of ≥2 exacerbations per year.
- Avoid accidental exceedance: The storm‑like supratherapeutic exposure can precipitate β₂‑agonist toxicity; thus, keep pump handle left side to remind patients of dosing limits.
- Formoterol onset: Rapid onset allows using Symbicort as an add‑on rescue (in conjunction with a short‑acting β₂‑agonist) *only in patients who have been titrated appropriately*; it is not intended alone for acute relief.
- Pregnancy & lactation: Evidence suggests no major teratogenic risk but ocular irritation is possible; instruct to rinse mouth and avoid nursing if systemic absorption is high.
- Drug interaction check: In patients on CYP3A4 inhibitors (e.g., macrolides, azoles), monitor for increased formoterol systemic exposure and β₂‑agonist cardiac effects.
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• References (for further reading)
1. Global Initiative for Asthma (GINA). 2024 Update.
2. Global Initiative for Chronic Obstructive Lung Disease (GOLD). 2024 Report.
3. Symbicort (budesonide/formoterol) prescribing information, Janssen Pharmaceuticals.
*This drug card serves as a concise reference for medical students and clinicians. Always consult the full prescribing information before clinical use.*