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Alpha blocker Silodosin: Side Effects and Dosage

• Alpha blockers: General pharmacology
• Alpha blocker Alfuzosin
• Alpha blocker Doxazosin
• Alpha blocker Silodosin
• Alpha blocker Tamsulosin
• Alpha blocker Terazosin

Mechanism of Action of Silodosin

Silodosin is a selective alpha_1A-blocker with a long half-life and favorable cardiovascular side effects (Cantrell et al., 2010). Please see section general pharmacology of alpha blocker.

Structural formula of silodosin

Indications for Silodosin

• Treatment of lower urinary tract symptoms due to benign prostatic hyperplasia.
• Off-label treatment of female LUTS due to neurogenic bladder neck obstruction.
• Off-label treatment: improve the spontaneous passage of distal ureteral stones.

Pharmacokinetics of Silodosin

Bioavailability 32%, high plasma protein binding, hepatic metabolization, elimination half life 13 h, biliary and renal excretion of metabolites.

General Side Effects of Alpha Blocker

Decreased side effect profile since silodosin is a selective α1A blocker.

• Hypotension, orthostatic syncope, reflex tachycardia
• Stuffy nose
• Retrograde ejaculation
• Dizziness, weakness
• Overall rate of side effects is between 10–30%.

Contraindications of Silodosin

Urological Contraindications:

Conservative treatment of BPH with silodosin is not indicated, if surgical treatment is imperative: chronic urinary retention with renal failure, recurrent hematuria due to prostatic enlargement, recurrent infections and bladder stones.

Cardiac Contraindications:

Hypotension, mechanical heart failure (valvular, pulmonary embolism, pericarditis), congestive heart failure.

Other contraindications:

Silodosin should be paused perioperatively for cataract surgery to prevent an intraoperative floppy iris syndrome.

Specific Contraindications of Silodosin

• Severe chronic kidney disease (<30 ml/min)
• Not approved in children.
• Inhibitors of CYP3A4 like ketoconazol

Dosage of Silodosin

8 mg orally once daily. Reduce dosage to 4 mg in patients with renal insufficiency (<50 ml/min).

References

  Deutsche Version: Silodosin