Products
Silodosin has been approved in hard capsule form in the United States since 2008, in the EU since 2010, and in many countries since 2016 (Urorec). Generic versions are registered in some countries.
Structure and properties
Silodosin (C25H32F3N3O4, Mr = 495.5) exists as a white to yellowish powder that is sparingly soluble in water. It has structural similarities to the pharmacologically comparable tamsulosin and is not a quinazoline derivative like terazosin and alfuzosin.
Effects
Silodosin (ATC G04CA04) binds as a competitive antagonist to postsynaptic α1-adrenoreceptors, thereby relaxing prostatic and urethral smooth muscle. This increases urinary flow, improves urination and filling symptoms. Because of its selectivity for the α1A receptor (urinary tract) versus the α1B receptor (vasculature), fewer cardiovascular side effects should occur, as with tamsulosin.
Indications
For the treatment of signs and symptoms of benign prostatic hyperplasia (BPH) in adult men.
Dosage
According to the SmPC. The capsule is taken once daily with a meal and always at the same time of day.
Contraindications
- Hypersensitivity
For complete precautions, see the drug label.
Interactions
Silodosin is metabolized by CYP3A4, alcohol dehydrogenase, and UGT2B7. It is a substrate for P-glycoprotein. Other interactions are possible with drugs that lower blood pressure.
Adverse effects
The most common possible adverse effects include ejaculatory dysfunction, dizziness, low blood pressure, nasal congestion, and diarrhea.
