Symbicort (Budesonide / Formoterol)
budesonide and formoterol fumarate dihydrate inhalation aerosol
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Asthma — maintenance treatment | ≥6 years | ICS/LABA for patients not controlled on ICS alone or warranting dual therapy | FDA Approved |
| COPD — maintenance of airflow obstruction and exacerbation reduction (160/4.5 only) | Adults | Maintenance; patients with exacerbation history | FDA Approved |
Budesonide-formoterol (Symbicort) is a fixed-dose ICS/LABA combination approved for asthma in patients 6 years and older and for COPD maintenance in adults. In asthma, it is reserved for patients not adequately controlled on ICS alone or whose disease warrants initiation of dual therapy. GINA guidelines position ICS/LABA at step 3 and above, and notably endorse low-dose budesonide-formoterol as both maintenance and reliever therapy (MART strategy) in some contexts, although this specific use is not FDA-approved. For COPD, only the 160/4.5 strength is indicated. Symbicort is not for the relief of acute bronchospasm.
Maintenance and reliever therapy (MART / SMART strategy): GINA recommends low-dose budesonide-formoterol as both daily controller and as-needed reliever for mild-to-moderate asthma. This approach reduces exacerbations compared with ICS plus SABA reliever. Not FDA-approved in the US for this use. Evidence quality: High (multiple RCTs).
Asthma-COPD overlap (ACO): ICS/LABA combinations are a cornerstone of ACO management per GOLD/GINA recommendations. Evidence quality: Moderate.
Dosing
Asthma — Adults & Adolescents (≥12 Years)
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Mild-to-moderate persistent asthma — inadequately controlled on low-dose ICS | 2 inh of 80/4.5 mcg BID | 2 inh of 80/4.5 BID | 2 inh of 160/4.5 BID (640/18 mcg/day) | Step up to 160/4.5 after 1–2 weeks if inadequate Onset within 15 min; max benefit 2 weeks+ |
| Moderate-to-severe persistent asthma — on medium/high-dose ICS or warranting dual therapy | 2 inh of 160/4.5 mcg BID | 2 inh of 160/4.5 BID | 2 inh of 160/4.5 BID (640/18 mcg/day) | Titrate to lowest effective dose once stable Do not exceed 2 inhalations BID of any strength |
Asthma — Pediatric (6 to <12 Years)
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Persistent asthma — not controlled on ICS alone | 2 inh of 80/4.5 mcg BID | 2 inh of 80/4.5 BID | 2 inh of 80/4.5 BID | Only strength approved for ages 6–11 Safety profile similar to adults at this dose |
COPD — Adults
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| COPD maintenance with exacerbation history | 2 inh of 160/4.5 mcg BID | 2 inh of 160/4.5 BID | 2 inh of 160/4.5 BID | 160/4.5 is the only COPD-approved strength Pneumonia not increased vs placebo in Symbicort COPD trials |
Formoterol has a rapid onset of bronchodilation (within 1–3 minutes), which is significantly faster than salmeterol (~10–20 minutes). This rapid onset underpins the GINA-endorsed MART strategy (not FDA-approved) and makes budesonide-formoterol attractive for patients who value quick symptom perception after dosing. Maximum anti-inflammatory benefit still requires 2 weeks or longer of regular use. Do not exceed 2 inhalations twice daily of the prescribed strength, and never add a separate LABA product.
Pharmacology
Mechanism of Action
Budesonide (ICS component): A non-halogenated glucocorticoid with potent topical anti-inflammatory activity and a favorable ratio of local-to-systemic effects. Budesonide binds intracellular glucocorticoid receptors, modulating transcription to suppress inflammatory mediators (cytokines, leukotrienes, prostaglandins) and reduce eosinophil, mast cell, and lymphocyte recruitment. A unique feature of budesonide is its ability to undergo reversible fatty acid esterification within airway epithelial cells, creating an intracellular depot that prolongs local anti-inflammatory duration beyond what plasma half-life would predict.
Formoterol (LABA component): A selective, long-acting beta2-agonist with a rapid onset of action (~1–3 minutes). Formoterol relaxes bronchial smooth muscle through beta2-receptor stimulation, increasing intracellular cyclic AMP. Unlike salmeterol, formoterol achieves near-full receptor activation rapidly due to its moderate lipophilicity, providing both fast-acting relief and sustained 12-hour bronchodilation. The ICS/LABA combination achieves complementary anti-inflammatory and bronchodilator effects that together provide superior asthma control compared with increasing the ICS dose alone.
ADME Profile
| Parameter | Budesonide | Formoterol |
|---|---|---|
| Absorption | Oral bioavailability ~6–11% (extensive first-pass ~90%); MDI lung deposition ~34%; rapid pulmonary absorption | Rapid pulmonary absorption; onset of bronchodilation within 1–3 min; Tmax ~10 min (inhaled) |
| Distribution | Vd: ~3 L/kg; protein binding: 85–90%; undergoes reversible fatty acid esterification in lung tissue (intracellular retention) | Protein binding: 61–64% (albumin); distributed into tissues |
| Metabolism | Hepatic via CYP3A4 to 16α-hydroxyprednisolone and 6β-hydroxybudesonide (∼100× less active than parent) | Direct glucuronidation (major); O-demethylation via CYP2D6 and CYP2C |
| Elimination | t½: ~2.8 h; ~60% urine, ~40% feces (as metabolites) | t½: ~10 h; excreted in urine (majority) and feces |
Side Effects
Asthma (FDA PI Table 1 — Adults/Adolescents ≥12 y, Pooled 3 Studies)
| Adverse Effect | Incidence (80/4.5 | 160/4.5) | Clinical Note |
|---|---|---|
| Nasopharyngitis | 10.5% | 9.7% | Placebo 9.0%; most common event; not clearly drug-related |
| Headache | 6.5% | 11.3% | Placebo 6.5%; dose-related at 160/4.5 (11.3%) |
| Upper respiratory tract infection | 7.6% | 10.5% | Placebo 7.8% |
| Adverse Effect | Incidence (80/4.5 | 160/4.5) | Clinical Note |
|---|---|---|
| Pharyngolaryngeal pain | 6.1% | 8.9% | Placebo 4.8% |
| Sinusitis | 5.8% | 4.8% | Placebo 4.8% |
| Stomach discomfort | 1.1% | 6.5% | Placebo 1.8%; notably dose-related |
| Influenza | 3.2% | 2.4% | Placebo 1.3% |
| Back pain | 3.2% | 1.6% | Placebo 0.8% |
| Vomiting | 1.4% | 3.2% | Placebo 1.0% |
| Nasal congestion | 2.5% | 3.2% | Placebo 1.0% |
| Oral candidiasis | 1.4% | 3.2% | Placebo 0.8%; emphasize mouth rinsing after use |
COPD-Specific (FDA PI Table 2 — 160/4.5, Pooled 2 Studies)
| Adverse Effect | Incidence (160/4.5) | Clinical Note |
|---|---|---|
| Nasopharyngitis | 7.3% | Placebo 4.9% |
| Oral candidiasis | 6.0% | Placebo 1.8%; higher than in asthma trials; emphasize mouth rinsing |
| Bronchitis | 5.4% | Placebo 3.5% |
| Sinusitis | 3.5% | Placebo 1.8% |
| Upper respiratory tract infection viral | 3.5% | Placebo 2.7% |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Lung infections other than pneumonia (COPD) | 7.6–8.1% (160/4.5) vs 3.3–6.2% placebo | Variable | Pneumonia itself was NOT increased vs placebo (1.1% vs 1.3% in 6-mo; 4.0% vs 5.0% in 12-mo). Differentiate from pneumonia clinically. |
| Adrenal suppression / HPA dysfunction | Rare at recommended doses | Weeks to months | Gradual dose reduction; cortisol assessment during steroid taper or stress |
| Hypersensitivity (urticaria, angioedema, bronchospasm) | Rare (postmarketing) | Minutes after dose | Discontinue; emergency treatment if anaphylaxis |
| Paradoxical bronchospasm | Rare | Immediately after inhalation | Rescue bronchodilator; discontinue Symbicort; alternative therapy |
| Cardiovascular effects (tachycardia, arrhythmias, QTc prolongation) | Uncommon; dose-related for formoterol | Variable | Use with caution in cardiovascular disease; ECG if symptomatic |
| Posterior subcapsular cataracts (COPD 12-mo study) | 9.0% score increase (160/4.5) vs 5.2% placebo (in subset of 461 patients) | Months to years | Periodic ophthalmological exams; refer for visual changes |
| Growth suppression (pediatric) | ~1 cm/year reduction (ICS class effect) | First year | Regular stadiometry; titrate to lowest effective dose |
Unlike fluticasone-based ICS/LABA combinations, budesonide-formoterol did not show a significant increase in pneumonia incidence compared with placebo in COPD trials (1.1% vs 1.3% at 6 months; 4.0% vs 5.0% at 12 months). Non-pneumonia lung infections were increased (7.6–8.1% vs 3.3–6.2%). This difference may relate to budesonide’s lower lipophilicity and faster clearance from the lung compared to fluticasone propionate, although head-to-head data are limited.
Drug Interactions
Budesonide is metabolized primarily via CYP3A4; formoterol via direct glucuronidation and CYP2D6/2C. No formal drug interaction studies have been performed with Symbicort, but concurrent use with short-acting beta2-agonists, intranasal corticosteroids, and antihistamines did not increase adverse reactions in clinical studies.
Monitoring
- Lung FunctionBaseline; 1–2 weeks; then q3–12 mo
RoutineImprovement may begin within 15 minutes; max benefit 2 weeks+. Step up if inadequate after 1–2 weeks at 80/4.5. - Oropharyngeal ExamEach visit
RoutineCandidiasis 1.4–3.2% in asthma, 6.0% in COPD. Reinforce mouth rinsing after every dose. - Growth (Pediatric)Every 3–6 months
RoutineICS class effect: ~1 cm/year growth velocity reduction. Titrate to lowest effective dose. - OphthalmologyAnnually for long-term users
RoutineIn COPD 12-month subset (461 patients), posterior subcapsular score increase: 9.0% (160/4.5) vs 5.2% placebo. Screen for cataracts and glaucoma. - Bone DensityBaseline (COPD); per risk factors
Trigger-based12-month COPD study: BMD for hip and spine were stable over treatment period. DEXA scan recommended for patients with osteoporosis risk factors. - Adrenal FunctionDuring steroid taper; if Cushingoid features
Trigger-basedCortisol assessment when transferring from oral steroids or using high-dose budesonide chronically. - Potassium / GlucoseIf concurrent diuretics or diabetes
Trigger-basedClinically significant changes in glucose and potassium were infrequent in Symbicort clinical trials.
Contraindications & Cautions
Absolute Contraindications
- Status asthmaticus or acute episodes of asthma/COPD requiring intensive measures
- Known hypersensitivity to budesonide, formoterol, or any excipient — postmarketing reports of anaphylaxis, angioedema, urticaria, and bronchospasm
Relative Contraindications (Specialist Input Recommended)
- Active or quiescent pulmonary tuberculosis
- Untreated systemic fungal, bacterial, viral, or parasitic infections
- Ocular herpes simplex
Use with Caution
- Cardiovascular disorders — coronary insufficiency, arrhythmias, hypertension; formoterol can produce clinically significant cardiovascular stimulation
- Convulsive disorders, thyrotoxicosis — sympathomimetic amine effects
- Diabetes mellitus — beta2-agonists may aggravate hyperglycemia
- Hepatic impairment — budesonide cleared via CYP3A4; monitor for increased systemic exposure
- Concurrent strong CYP3A4 inhibitors — increased budesonide exposure
- Do not combine with other LABA-containing products
Long-acting beta2-adrenergic agonists such as formoterol increase the risk of asthma-related death when used without an ICS. This finding is based on the SMART trial with salmeterol (13 deaths per 13,176 vs 3 per 13,179 on placebo; RR 4.37) and is considered a class effect of all LABAs including formoterol. No study adequate to determine whether asthma-related death is increased with Symbicort specifically has been conducted. Symbicort should only be used for patients not adequately controlled on ICS alone or whose severity warrants dual therapy. Once control is achieved, assess regularly and step down if possible.
Deaths due to adrenal insufficiency have occurred during and after transfer from systemic corticosteroids to inhaled corticosteroids. Taper prednisone by 2.5 mg/day on a weekly basis after ≥1 week on Symbicort. Patients previously on ≥20 mg/day prednisone are most susceptible.
Patient Counselling
Purpose of Therapy
Symbicort contains two medicines: budesonide (a corticosteroid that reduces airway inflammation) and formoterol (a long-acting bronchodilator that relaxes airway muscles for 12 hours). Together they prevent asthma or COPD symptoms more effectively than either alone. Symbicort is a controller — it must be used every day and is not for sudden breathing problems.
How to Take
Take 2 inhalations twice daily, approximately 12 hours apart. Shake well for 5 seconds before each inhalation. Prime with 2 sprays before first use or if not used for more than 7 days. After every dose, rinse the mouth with water and spit it out. Always carry a separate rescue inhaler. Never exceed the prescribed dose or add another LABA product.
Sources
- Symbicort (budesonide and formoterol fumarate dihydrate) inhalation aerosol prescribing information. AstraZeneca. Revised 2017. FDA Label Primary source for all dosing, adverse reaction Tables 1 and 2, pharmacokinetic data, boxed warning text, and drug interaction guidance.
- DailyMed — Symbicort label. National Library of Medicine. DailyMed Current structured FDA-approved labeling with full prescribing information.
- Rabe KF, Pizzichini E, Stallberg B, et al. Budesonide/formoterol in a single inhaler for maintenance and relief in mild-to-moderate asthma. Chest. 2006;129(2):246–256. DOI Key trial supporting the MART/SMART concept of budesonide-formoterol as both maintenance and reliever therapy.
- O’Byrne PM, FitzGerald JM, Bateman ED, et al. Inhaled combined budesonide-formoterol as needed in mild asthma. N Engl J Med. 2018;378(20):1865–1876. DOI SYGMA 1 trial demonstrating as-needed budesonide-formoterol was superior to as-needed SABA for symptom control in mild asthma.
- Reddel HK, FitzGerald JM, Bateman ED, et al. GINA 2019: a fundamental change in asthma management. Eur Respir J. 2019;53(6):1901046. DOI Landmark GINA update that placed budesonide-formoterol as preferred reliever across all asthma steps.
- Tashkin DP, Rennard SI, Martin P, et al. Efficacy and safety of budesonide and formoterol in one pressurized metered-dose inhaler in patients with moderate to very severe chronic obstructive pulmonary disease. Drugs. 2008;68(14):1975–2000. DOI Pivotal COPD efficacy trial supporting the 160/4.5 BID indication; source of COPD adverse event data.
- Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2024 Update. GINA Reports Positions ICS/LABA at step 3+ and endorses low-dose budesonide-formoterol as preferred reliever across all steps.
- Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for Prevention, Diagnosis and Management of COPD. 2024 Report. GOLD Reports COPD guideline positioning ICS/LABA for patients with exacerbation history and elevated eosinophil counts.
- Miller-Larsson A, Mattsson H, Hjertberg E, et al. Reversible fatty acid conjugation of budesonide: novel mechanism for prolonged retention of topically applied steroid in airway tissue. Drug Metab Dispos. 1998;26(7):623–630. PubMed Describes the unique intracellular fatty acid esterification of budesonide that prolongs local anti-inflammatory activity beyond what plasma half-life predicts.
- Barnes PJ. Scientific rationale for inhaled combination therapy with long-acting beta2-agonists and corticosteroids. Eur Respir J. 2002;19(1):182–191. DOI Review of the synergistic molecular mechanisms underlying ICS/LABA combination therapy.
- Donnelly R, Williams P, Coughtrie MWH, et al. Clinical pharmacokinetics of inhaled budesonide. Clin Pharmacokinet. 2001;40(6):427–440. DOI Comprehensive PK review: Vd ~3 L/kg, protein binding 85–90%, t½ ~2–3 h, oral bioavailability ~6–13% after first-pass.
- Cazzola M, Page CP, Calzetta L, et al. Pharmacology and therapeutics of bronchodilators. Pharmacol Rev. 2012;64(3):450–504. DOI Comprehensive pharmacology review covering formoterol PK, rapid onset mechanism, and 12-hour duration of action.