Winrevair
Winrevair
Generic Name
Winrevair
Mechanism
- Selective β₂‑adrenergic receptor agonist: Rapidly stimulates Gs‑protein‑coupled β₂ receptors on airway smooth muscle.
- Increases cAMP levels → activates protein kinase A → phosphorylation of myosin light‑chain kinase → smooth‑muscle relaxation.
- Secondary effects: Modest anti‑inflammatory influence by decreasing eosinophil chemotaxis and reducing airway hyperresponsiveness.
*(The drug’s receptor‑binding kinetics show a dissociation half‑life of ~4 h, supporting twice‑daily dosing.)*
Pharmacokinetics
| Parameter | Value (inhaled) |
| Absorption | ~70 % of the deposited dose is absorbed in the alveolar space; rapid peak plasma concentration (t₁ₒₚ ≈ 5 min). |
| Distribution | Primarily to lung tissue; low systemic exposure (Cₚₒₓ ≈ 5 % of inhaled dose). |
| Metabolism | β‑oxidation and CYP3A4‑mediated oxidative desaturation (≈ 15 % of dose). |
| Half‑life | Elimination t½ ≈ 5 h (lung depot); systemic t½ ≈ 9 h. |
| Excretion | ~60 % renal (urine); remainder biliary/fecal. |
| Protein Binding | < 10 % (predominantly unbound). |
| Drug‑Drug Interactions | Strong CYP3A4 inhibitors may increase systemic exposure; concomitant use with systemic beta‑blockers contraindicated. |
Indications
- Asthma – maintenance, long‑term control (used with inhaled corticosteroid).
- COPD – once‑daily or twice‑daily bronchodilation for symptom relief and exacerbation prevention.
Contraindications
| Category | Contraindication/Warning |
| Contraindications | Known hypersensitivity to Winrevair or any excipient; severe cardiac arrhythmias. |
| Warnings |
• Cardiovascular: tachycardia, palpitations, hypertension, arrhythmias. • Pulmonary: paradoxical bronchospasm (rare). • Metabolic: hypokalemia, hyperglycemia with chronic use. |
| Precautions |
• Use with inhaled corticosteroid in asthma (avoid monotherapy). • Monitor electrolyte and cardiac status in patients on concomitant medications affecting potassium or QT interval. |
Dosing
- Adult dosing
- *COPD/Asthma*: 2 puffs (20 µg each) via dry‑powder inhaler twice daily (morning & evening).
- *Adjust*: For patients with severe bronchospasm, extend interval to 12 h.
- Pediatric (5–12 y): 2 puffs (10 µg each) once daily; not recommended under 5 y.
- Administration:
- Use spacer for patients with coordination difficulties.
- Rinse mouth after use to reduce oral candidiasis risk.
> Note: Never exceed 4 puffs/day.
Adverse Effects
| Common (≥ 5 %) | Serious (≤ 1 %) |
| Tremor | Severe cardiovascular events (arrhythmia, myocardial infarction) |
| Palpitations | Hypotension |
| Nasal irritation | Hypokalemia |
| Headache | Exacerbation of asthma (paradoxical bronchospasm) |
| Dry mouth | Pulmonary edema |
| Insomnia | Hypersensitivity reactions |
*(Symptoms should be reported; consider dose adjustment or discontinuation with serious events.)*
Monitoring
- Baseline and every 3 months:
- Blood pressure & heart rate.
- Serum electrolytes (potassium, glucose).
- Spirometry: FEV₁ at baseline, then every 3 months or during exacerbations.
- Pulmonary function: Peak expiratory flow (PEF) daily if patient is unstable.
- Adverse event surveillance: Record any tremor, arrhythmia, or bronchospasm episodes.
Clinical Pearls
- Beta‑agonist + steroid synergy: Pair Winrevair with an inhaled corticosteroid in asthma to prevent tolerance and reduce exacerbations.
- Avoid monotherapy in acute asthmatic attacks: Use rescue short‑acting β₂‑agonist (SABA) instead.
- Dosing schedule: For COPD patients with nighttime symptoms, consider evening dose to prolong overnight bronchodilation.
- Electrolyte monitoring: Chronic use may lower potassium; supplement potassium in at-risk patients (e.g., those on diuretics).
- Contraindicated with cardiac β‑blockers: Unselective β‑blockers (e.g., propranolol) may blunt bronchodilation; cardioselective agents (e.g., atenolol) should be avoided unless absolutely necessary.
*This drug card summarizes current evidence; clinicians should review the full prescribing information and consult the latest guidelines when making therapeutic decisions.*