Silodosin

BRAND NAMES:

Silodyx: Silodyx contains the active components of silodosin. It is available in pill form and is intended to treat the symptoms of benign prostate hyperplasia in adults.

Rapaflo: Rapaflo includes the active components from silodosin. It is offered as capsules.

Urorec: Urorec includes the active components from silodosin. It is offered as capsules.

MEACHNISM OF ACTION:

Silodosin works by inhibiting the α1A-adrenoceptor signalling pathway, which relaxes prostatic and urethral smooth muscles and improves lower urinary tract symptoms, including voiding. Silodosin also affects afferent neurones in the bladder, reducing bladder overactivity and storing symptoms.

PHARMACOKINETICS:

ABSORPTION: Silodosin has an absolute bioavailability of about 32% following oral dosing. Silodosin's Tmax was 2.6 ± 0.90 hours.

DISTRIBUTION: The apparent volume of distribution of silodosin is 49.5L.

METABOLISM: Silodosin is metabolised by the enzyme CYP3A4, which catalyses the oxidation process. Silodosin's key metabolic routes, in addition to glucuronidation, dehydrogenation, and oxidation, include dealkylation, N-dealkylation, hydroxylation, glucosylation, and sulphate conjugation.

EXCRETION: The excretion of silodosin is 33.5% of the dose recovered in the urine, and 54.9% was recovered in feces.

PHARMACODYNAMICS:

Silodosin binds to α1A-adrenoaceptors and relaxes the lower urinary tract, reducing symptoms and preventing bladder outlet blockage. 

DOSAGE AND ADMINISTRATION:

Silodosin is available in the form of capsules for oral administration. It is typically taken with meals once per day. Avoid taking silodosin on an empty stomach. Take silodosin at the same time each day. 
Silodosin capsules are available in dosages of 4 mg and 8 mg.

DRUG INTERACTIONS:

Drug interactions of silodosin may include

• Antifungal: itraconazole, ketoconazole
• Blood pressure-lowering pills: verapamil, metoprolol, and diltiazem
• Antiviral: ritonavir
• Immune suppression drugs: cyclosporine
• Antibiotics: clarithromycin, erythromycin
• Erectile dysfunction pills: tadalafil and sildenafil

CONTRAINDICATIONS:

Silodosin is contraindicated with hypersensitivity, severe renal impairment, severe hepatic impairment, and concomitant strong CYP3A4 inhibitors and P-glycoprotein inhibitors.

SIDE EFFECTS:

Side effects of silodosin may include

• Diarrhoea
• Stuffy nose
• Dizziness
• Low blood pressure

Side effects of silodosin may include

• Painful erection of penis that lasts for several hours

OVERDOSE:

Symptoms of overdose may include

• Fainting
• Blurred vision
• Dizziness
• Light headedness

TOXICITY:

In the situation of a chemical overdose that causes hypotension, the patient should be put in a supine posture to restore blood pressure and heart rate. Additional procedures, such as administering intravenous fluids, may be implemented. When using vasopressors, the actual function should be monitored and supported as needed. Silodosin is heavily attached to plasma proteins; hence, dialysis is unlikely to be useful.