Usage
Solifenacin + Tamsulosin is prescribed for the treatment of moderate to severe storage symptoms (urgency, frequency) and voiding symptoms associated with benign prostatic hyperplasia (BPH) in men who have not adequately responded to monotherapy.
Pharmacological Classification:
- Solifenacin: Muscarinic receptor antagonist, specifically M3 selective.
- Tamsulosin: α1-adrenergic receptor antagonist, specifically α1A and α1D selective.
Mechanism of Action: This combination targets two distinct mechanisms involved in BPH and lower urinary tract symptoms (LUTS). Solifenacin reduces bladder contractions by blocking M3 receptors in the detrusor muscle, thus alleviating storage symptoms. Tamsulosin relaxes smooth muscle in the prostate and bladder neck by blocking α1-adrenergic receptors, improving urine flow and reducing voiding symptoms.
Alternate Names
The combination of Solifenacin and Tamsulosin is not widely known by other generic names. It is sometimes described simply as solifenacin/tamsulosin fixed-dose combination (FDC) therapy.
Brand Names: Vesomni®, Tamsolin-S®, Solifenacin/Tamsulosin Clonmel, Vecit and other generic variations.
How It Works
Pharmacodynamics:
- Solifenacin: Reduces detrusor muscle contractility, increasing bladder capacity and reducing urgency and frequency.
- Tamsulosin: Decreases smooth muscle tone in the prostate and bladder neck, reducing urethral resistance and improving urine flow.
Pharmacokinetics:
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Solifenacin:
- Absorption: Well-absorbed after oral administration, with food having minimal effect.
- Metabolism: Primarily hepatic, via CYP3A4.
- Elimination: Mainly renal excretion.
-
Tamsulosin:
- Absorption: Well-absorbed after oral administration, with food slightly delaying absorption.
- Metabolism: Primarily hepatic.
- Elimination: Mainly renal excretion.
Mode of Action/ Receptor Binding/ Enzyme Inhibition:
Solifenacin competitively binds to M3 muscarinic receptors in the bladder, inhibiting acetylcholine-mediated detrusor contractions. Tamsulosin competitively binds to α1A and α1D adrenergic receptors in the prostate and bladder neck, inhibiting norepinephrine-mediated smooth muscle contraction. Neither drug significantly inhibits CYP450 enzymes at therapeutic doses.
Dosage
Standard Dosage
Adults:
One tablet (6 mg solifenacin/0.4 mg tamsulosin) orally once daily, with or without food. The tablet should be swallowed whole and not crushed or chewed.
Children: This combination is not indicated for use in children.
Special Cases:
-
Elderly Patients: Standard adult dose, but monitor for potential adverse effects.
-
Patients with Renal Impairment:
- Mild to moderate (creatinine clearance > 30 mL/min): Standard adult dose.
- Severe (creatinine clearance ≤ 30 mL/min): Use with caution; maximum daily dose is one tablet.
-
Patients with Hepatic Dysfunction:
- Mild (Child-Pugh score ≤ 7): Standard adult dose.
- Moderate (Child-Pugh score 7-9): Use with caution; maximum daily dose is one tablet.
- Severe (Child-Pugh score > 9): Contraindicated.
Clinical Use Cases
Solifenacin + Tamsulosin is not indicated for use in intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. Its use is limited to the management of BPH/LUTS.
Side Effects
Common Side Effects:
Dry mouth, dizziness, blurred vision, constipation, nausea, dyspepsia, abnormal ejaculation (including retrograde ejaculation).
Rare but Serious Side Effects:
Angioedema, anaphylaxis, urinary retention, QT interval prolongation, narrow-angle glaucoma.
Long-Term Effects:
Limited data exists for long-term effects however, solifenacin has the possibility of increase risk of cognitive decline.
Contraindications
- Hypersensitivity to solifenacin, tamsulosin, or any component of the formulation.
- Urinary retention.
- Gastric retention.
- Uncontrolled narrow-angle glaucoma.
- Severe hepatic impairment (Child-Pugh score > 9).
- Patients undergoing hemodialysis.
Drug Interactions
- Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): Use with caution; may increase exposure to both drugs.
- Moderate CYP3A4 inhibitors (e.g., verapamil, erythromycin): Use with caution.
- Other alpha-blockers: May potentiate hypotensive effects.
- Anticholinergics: May increase anticholinergic side effects.
Pregnancy and Breastfeeding
Solifenacin + Tamsulosin is not indicated for use in women. Therefore, pregnancy and breastfeeding safety categories are not applicable.
Drug Profile Summary
- Mechanism of Action: Solifenacin (antimuscarinic) reduces bladder contractions; Tamsulosin (alpha-blocker) relaxes prostate and bladder neck smooth muscle.
- Side Effects: Dry mouth, dizziness, blurred vision, constipation, abnormal ejaculation. Rarely: angioedema, anaphylaxis, urinary retention.
- Contraindications: Hypersensitivity, urinary retention, gastric retention, narrow-angle glaucoma, severe hepatic impairment, hemodialysis.
- Drug Interactions: Strong CYP3A4 inhibitors, other alpha-blockers, anticholinergics.
- Pregnancy & Breastfeeding: Not applicable (not for use in women).
- Dosage: One tablet (6 mg/0.4 mg) orally once daily.
- Monitoring Parameters: Blood pressure, prostate-specific antigen (PSA), urinary flow rate, post-void residual (PVR) volume.
Precautions
- Assess for pre-existing medical conditions, including renal and hepatic impairment.
- Monitor for orthostatic hypotension, especially in the elderly.
- Caution in patients with a history of QT prolongation.
FAQs
Q1: What is the recommended dosage for Solifenacin + Tamsulosin?
A: One tablet (6 mg solifenacin/0.4 mg tamsulosin) orally once daily.
Q2: Can Solifenacin + Tamsulosin be used in patients with renal impairment?
A: Yes, but with caution. In patients with severe renal impairment (creatinine clearance ≤ 30 mL/min), the maximum dose is one tablet daily.
Q3: What are the most common side effects?
A: Dry mouth, dizziness, blurred vision, and constipation.
Q4: Are there any serious side effects?
A: Although rare, serious side effects include angioedema, anaphylaxis, and acute urinary retention.
Q5: What are the contraindications for using this medication?
A: Contraindications include hypersensitivity, urinary retention, gastric retention, uncontrolled narrow-angle glaucoma, severe hepatic impairment and hemodialysis.
Q6: Can this drug be crushed or chewed?
A: No, the tablets should be swallowed whole. Crushing or chewing can alter drug release and potentially lead to adverse effects.
Q7: Can patients drink alcohol while taking this medication?
A: While moderate alcohol consumption is not strictly contraindicated, caution is advised as it may exacerbate dizziness and other side effects.
Q8: What should patients do if they miss a dose?
A: Patients should take the missed dose as soon as remembered, unless it is close to the time for the next dose. In that case, they should skip the missed dose and take the next dose at the regular time. They should not double the dose.
Q9: How should this drug be stored?
A: Store at room temperature, protected from moisture and excessive heat.
