Usage
Trospium is prescribed for the treatment of overactive bladder (OAB) with symptoms of urinary urgency, frequency, and urge urinary incontinence. It is pharmacologically classified as an antimuscarinic agent, specifically a competitive muscarinic receptor antagonist. Trospium works by blocking the action of acetylcholine at muscarinic receptors in the bladder, thus inhibiting involuntary bladder contractions and reducing the urge to urinate.
Alternate Names
Trospium chloride is the chemical name. A commonly used brand name is Sanctura (for both immediate-release tablets and extended-release capsules), and Sanctura XR (specifically for the extended-release capsules).
How It Works
Pharmacodynamics: Trospium exerts its therapeutic effect by competitively antagonizing the muscarinic receptors in the bladder, primarily the M2 and M3 subtypes. This action inhibits the binding of acetylcholine, a neurotransmitter that stimulates bladder contractions. By reducing the sensitivity of the detrusor muscle to acetylcholine, trospium decreases the frequency and intensity of bladder contractions, thereby improving bladder capacity and control.
Pharmacokinetics:
- Absorption: Trospium is well-absorbed after oral administration, but absolute bioavailability is low (approximately 9% for immediate-release tablets, and 20% for the extended-release capsules).
- Metabolism: Minimally metabolized in the liver, with a small fraction converted to inactive metabolites. There is no evidence of polymorphism associated with cytochrome P450 (CYP) enzymes.
- Elimination: Primarily excreted unchanged in the urine. The elimination half-life is approximately 20 hours. Renal impairment significantly affects elimination and necessitates dose adjustments.
Dosage
Standard Dosage
Adults:
- Immediate-release tablets: 20 mg twice daily, taken on an empty stomach at least one hour before a meal.
- Extended-release capsules: 60 mg once daily in the morning, taken on an empty stomach at least one hour before a meal.
Children:
The safety and efficacy of trospium in children have not been established, and its use is not recommended in patients younger than 18 years.
Special Cases:
- Elderly Patients (≥75 years): Initial dose should be the same as for adults, but can be titrated down to 20 mg once daily based on individual tolerability, especially for the immediate-release tablets.
- Patients with Renal Impairment:
- Creatinine Clearance (CrCl) < 30 mL/min: 20 mg once daily at bedtime (immediate-release tablets only; extended-release is not recommended).
- CrCl 30-50 mL/min: Close monitoring is required; dosage adjustment may be necessary.
- Patients with Hepatic Dysfunction: Exercise caution, as dosage adjustments may be needed. Limited data available.
- Patients with Comorbid Conditions:
- Bladder outflow obstruction: Use with caution due to an increased risk of urinary retention.
- Gastrointestinal obstructive disorders: Use with caution due to an increased risk of gastric retention.
- Narrow-angle glaucoma: Use with caution and careful monitoring. Uncontrolled narrow-angle glaucoma is a contraindication.
Clinical Use Cases
Trospium’s clinical use is specifically focused on managing OAB symptoms and is not indicated for use in situations such as intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dosage adjustments based on renal function are crucial. For moderate to severe renal impairment (CrCl < 50 mL/min), careful monitoring and dose reductions might be required. Hepatic impairment and comedications should be carefully considered.
Side Effects
Common Side Effects
- Dry mouth
- Constipation
- Headache
- Blurred vision
- Abdominal pain or discomfort
- Dyspepsia
Rare but Serious Side Effects
- Angioedema (swelling of face, lips, tongue, or throat)
- Anaphylactic reaction
- Urinary retention
- Gastric retention
- Worsening of narrow-angle glaucoma
- Severe allergic reactions
Long-Term Effects
Long-term use might be associated with chronic dry mouth and constipation if not adequately managed.
Adverse Drug Reactions (ADR)
Clinically significant ADRs include angioedema, anaphylaxis, urinary retention, and worsening of glaucoma. These require immediate medical attention.
Contraindications
- Urinary retention
- Gastric retention
- Uncontrolled narrow-angle glaucoma
- Hypersensitivity to trospium or any of its components
Drug Interactions
Trospium can interact with several medications, including other antimuscarinics (e.g., antihistamines, tricyclic antidepressants), which can potentiate anticholinergic effects. Concomitant use with drugs that prolong the QT interval should be done with caution. It is important to disclose all current medications, including OTC drugs and supplements, to your doctor.
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CYP450 Interactions: Trospium is minimally metabolized by CYP enzymes. Metformin can decrease trospium levels.
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Interactions with Commonly prescribed medications: Other antimuscarinic drugs, such as those used to treat OAB, should be used with caution due to increased risk of shared side effects.
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OTC drugs and supplements: Some OTC antihistamines and sleep aids have antimuscarinic properties.
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Food and lifestyle factors: High-fat meals can alter the absorption of the extended-release formulation. Alcohol should not be consumed within 2 hours of taking extended-release trospium.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Category C (US FDA). Trospium should be used during pregnancy only if the potential benefit outweighs the risk to the fetus.
- Breastfeeding: It is unknown if trospium is excreted in breast milk. Caution should be exercised when administered to a nursing woman.
Drug Profile Summary
- Mechanism of Action: Muscarinic receptor antagonist, reducing bladder contractions.
- Side Effects: Dry mouth, constipation, headache, blurred vision, abdominal discomfort.
- Contraindications: Urinary/gastric retention, uncontrolled narrow-angle glaucoma, hypersensitivity.
- Drug Interactions: Other antimuscarinics, metformin.
- Pregnancy & Breastfeeding: Category C; use with caution if benefits outweigh risks.
- Dosage: Adults: IR: 20 mg BID; XR: 60 mg QD. Dose adjustment for renal impairment is required.
- Monitoring Parameters: Monitor for urinary retention, constipation, and signs of anticholinergic toxicity.
Popular Combinations
Trospium is generally used as monotherapy. However, combination therapy with other OAB medications may be considered if trospium alone isn’t effective.
Precautions
Standard precautions include assessing for allergies, renal/hepatic function, and other comorbidities. Patients should be counseled about potential side effects.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Trospium?
A: Adults: Immediate-release: 20 mg twice daily; Extended-release: 60 mg once daily. Dosages should be adjusted for renal impairment. Pediatric use is not recommended.
Q2: How should Trospium be taken?
A: On an empty stomach with water, at least one hour before a meal.
Q3: What are the common side effects of Trospium?
A: Dry mouth, constipation, headache, blurred vision, and abdominal discomfort.
Q4: What are the contraindications for Trospium?
A: Urinary retention, gastric retention, uncontrolled narrow-angle glaucoma, and hypersensitivity.
Q5: Can Trospium be used during pregnancy?
A: Pregnancy Category C. Use only if the potential benefit outweighs the risk to the fetus.
Q6: Can Trospium be used while breastfeeding?
A: It’s unknown if trospium passes into breast milk. Use with caution.
Q7: How does Trospium interact with other antimuscarinic medications?
A: Concomitant use may increase the frequency and severity of anticholinergic side effects.
Q8: Does Trospium affect renal function?
A: No, but renal impairment affects trospium elimination, requiring dosage adjustments.
Q9: What should patients be advised regarding lifestyle while taking Trospium?
A: Advise patients to avoid alcohol within 2 hours of taking extended-release trospium. Caution patients about potential blurred vision impacting driving.
