TIOTROPIUM BROMIDE
Clinical safety rating: safe
Animal studies have demonstrated safety
Tiotropium bromide is a long-acting, competitive, and reversible muscarinic receptor antagonist (anticholinergic). It binds preferentially to M3 receptors in the smooth muscle of the bronchi, inhibiting acetylcholine-mediated bronchoconstriction and mucus secretion, leading to prolonged bronchodilation.
| Metabolism | Tiotropium undergoes minimal hepatic metabolism via cytochrome P450 enzymes, primarily CYP2D6 and CYP3A4, but the extent is negligible (<20% of dose). The majority of the drug is excreted unchanged in urine via active tubular secretion. |
| Excretion | Primarily renal: 14% of dose excreted unchanged in urine; remainder as inactive metabolites via biliary/fecal (70%) and renal (30% total). |
| Half-life | Terminal elimination half-life: 5–6 days (inhalation). Longer half-life allows once-daily dosing. Steady-state reached in 2–3 weeks. |
| Protein binding | ~72% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | 32 L/kg (steady-state). High Vd indicates extensive tissue distribution, including lung tissue binding. |
| Bioavailability | Inhalation: Absolute bioavailability ~19.5% (due to lung deposition and oral fraction). Oral bioavailability negligible (<1%). |
| Onset of Action | Inhalation: Onset within 30 minutes (bronchodilation). |
| Duration of Action | Inhalation: Duration >24 hours (once-daily dosing). Bronchodilation sustained over 24h with minimal peak/trough fluctuation. |
| Molecular Weight | 472.4 |
Inhalation (oral): 18 mcg once daily via HandiHaler; or 2.5 mcg (2 puffs) once daily via Respimat inhaler.
| Dosage form | POWDER |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment (CrCl >=30 mL/min). For severe (CrCl <30 mL/min), use only if benefit outweighs risk; no specific dose adjustment established. |
| Liver impairment | No dosage adjustment required for hepatic impairment; pharmacokinetics not studied in Child-Pugh Classes B or C. |
| Pediatric use | Not approved for pediatric patients <18 years of age. |
| Geriatric use | No dose adjustment recommended; monitor for anticholinergic effects (e.g., urinary retention, constipation) due to age-related decline in renal function. |
| 1st trimester | Limited human data; animal studies show no teratogenicity at inhaled doses. Use only if benefit outweighs risk. |
| 2nd trimester | Limited human data; animal studies show no teratogenicity. Use only if benefit outweighs risk. |
| 3rd trimester | Limited human data; potential for uterine relaxation and preterm labor inhibition. Avoid near term due to anticholinergic effects. |
Clinical note
Other anticholinergic drugs can have additive effects Can cause paradoxical bronchospasm and narrow-angle glaucoma.
| Placental transfer | Following intravenous administration, tiotropium crosses the placenta in rats. In humans, placental transfer is likely limited due to quaternary ammonium structure and low passive diffusion. No specific data on degree. |
| Breastfeeding | Excretion into human milk unknown; due to low bioavailability and short half-life, infant exposure likely minimal. Use with caution. |
■ FDA Black Box Warning
None
| Common Effects | Dry mouth |
| Serious Effects |
Hypersensitivity to tiotropium or any component (including lactose)History of hypersensitivity reactions to atropine or its derivatives
| Precautions | Not indicated for acute bronchospasm or as rescue therapy, May cause paradoxical bronchospasm (discontinue immediately if occurs), Caution in patients with narrow-angle glaucoma (may worsen intraocular pressure), Caution in patients with urinary retention (prostatic hyperplasia or bladder-neck obstruction), Use with caution in patients with moderate to severe renal impairment (creatinine clearance <60 mL/min) due to increased systemic exposure, Immediate hypersensitivity reactions (angioedema, urticaria, rash, pruritus) may occur |
| Food/Dietary | No significant food-drug interactions known. Tiotropium is inhaled; systemic absorption is minimal. Drink adequate fluids to counteract dry mouth. |
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| Lactation Rating | L3 - Moderately Safe |
| Teratogenic Risk | FDA Pregnancy Category C. No adequate and well-controlled studies in pregnant women. In animal studies, tiotropium bromide caused fetal resorption, litter loss, delayed ossification, and decreased fetal weight at maternal toxic doses (approximately 5-10 times the maximum recommended human daily inhalation dose). Risk cannot be ruled out; use only if potential benefit justifies potential risk to the fetus. |
| Fetal Monitoring | Monitor for signs of anticholinergic toxicity (e.g., blurred vision, urinary retention, tachycardia) in mother and neonate. Assess fetal growth and well-being via ultrasound if used in pregnancy. |
| Fertility Effects | No human data. In animal studies, no impairment of fertility was observed at doses up to approximately 5 times the maximum recommended human daily inhalation dose. |
| Clinical Pearls | Tiotropium is a long-acting muscarinic antagonist (LAMA) used as maintenance bronchodilator in COPD and asthma. It is not for acute bronchospasm. Administered via HandiHaler, Respimat, or soft mist inhaler. Monitor for anticholinergic effects: dry mouth, constipation, urinary retention, and angle-closure glaucoma (if powder gets in eyes). Inhaled form has minimal systemic absorption, but caution in severe renal impairment (CrCl <30 mL/min). No dose adjustment needed for hepatic impairment. |
| Patient Advice | Use as a daily maintenance treatment, not for sudden breathing problems. · Do not swallow capsules; they are for inhalation only using the specific inhaler device. · Rinse mouth after each use to prevent dry mouth (avoid swallowing rinse water). · If a dose is missed, take it as soon as remembered but skip if next dose is due; do not double. · Store capsules in blister pack until use; protect from moisture. · Seek immediate medical help if signs of allergic reaction or eye pain/vision changes occur. · Inform doctor if you have glaucoma, prostate problems, or kidney issues. |