Spiriva
Tiotropium
Generic Name
Tiotropium
Mechanism
Tiotropium competitively blocks muscarinic M3 receptors on airway smooth muscle, preventing acetylcholine‑mediated bronchoconstriction.
* Selectivity: High affinity for M3 over M2/M1 receptors → minimal tachycardia and dry‑mouth.
* Duration: Binding is almost irreversible for ~24 h, enabling once‑daily dosing.
Pharmacokinetics
| Parameter | Typical Values (Adults) |
| Absorption | ~45 % bioavailability via inhalation (rapid pulmonary absorption). |
| Distribution | Large lung‑to‑plasma ratio; minimal systemic exposure. |
| Metabolism | Conjugation to glucuronide in the liver; no active metabolites. |
| Elimination | Renal (≈ 70 %) and fecal; half‑life ≈ 60 h. |
| Special populations | Minimal adjustment for renal impairment; caution in hepatic impairment (data limited). |
Indications
- Maintenance therapy for COPD (emphysema, chronic bronchitis).
- Maintenance therapy for asthma refractory to inhaled corticosteroids (ICS) and long‑acting β₂‑agonists (LABAs).
Contraindications
- Contraindicated in patients with known hypersensitivity to tiotropium or any component.
- Avoid in acute bronchospasm; use rescue inhaler first.
- Precautions:
- COPD patients with frequent exacerbations or heart failure (≥ NYHA class II).
- Asthmatic patients with comorbid asthma‑COPD overlap.
- Use caution in children < 12 yr (not approved).
Dosing
| Formulation | Dose | Frequency | Instructions |
| Spiriva Respimat® (inhaler) | 18 µg | Once daily (morning or bedtime) | Shake 3–5 s before use; inhale slowly, hold breath 5 s. |
| Spiriva Ellipta® (dry‑powder inhaler) | 18 µg | Once daily | Place device on mouth, inhale forcefully for 5 s. |
• Initial titration: Start at 18 µg once; if COPD exacerbation within 6 week and patient tolerates, consider stepping up to 36 µg (double‑dose) on alternate days.
• Combination: Can be used with inhaled corticosteroids or LABAs; no need for dose adjustment.
Adverse Effects
- Common (≤ 10 %)
- Dry mouth, dysphagia, cough, nasopharyngitis.
- Serious (> 1 %)
- Bradycardia, arrhythmias, heart failure exacerbation.
- Asthma–COPD overlap exacerbation.
- Urinary retention (rare).
Management: Monitor cardiac status; discontinue if symptomatic bradycardia or heart failure.
Monitoring
- Spirometry: FEV₁ and FVC pre‑ and post‑dose (baseline, 6 wks, 12 wks).
- ECG: In patients with known cardiac disease (baseline, 12 wks).
- Blood pressure: Especially in patients on β₁‑blockers.
- Symptom diaries: Exacerbation frequency, rescue inhaler use.
Clinical Pearls
- Fast‑track inhalation: The *Respimat®* form delivers a fine mist; ensure patient inhales slowly to maximize deposition, especially in severe COPD.
- Double‑dose strategy: In patients with COPD who continue to exhibit significant airflow limitation, a 36 µg dose on alternate days can be considered while monitoring heart rate.
- Combination synergy: Tiotropium is most effective when paired with an inhaled corticosteroid for asthma; however, avoid adding a LABA if the patient is already on a fixed‐dose combination inhaler.
- Avoid overuse: Although tiotropium is once‑daily, patients often misuse it as a rescue inhaler; emphasize the distinction from short‑acting bronchodilators.
- Dry‑mouth prophylaxis: Offer sugar‑free lozenges or stimulants (e.g., pilocarpine eye drops) for patients reporting xerostomia.
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• References *(summaries for quick reference)*
1. GOLD 2024 Report – COPD management algorithms.
2. NICE Guideline NG45 – Asthma.
3. LAMA pharmacology review, *Pulmonary Pharmacotherapy* 2023.