Silodosin


Concise Prescribing Info
Indications/Uses
Benign prostatic hyperplasia.
Dosage/Direction for Use
Adult : PO 8 mg daily as a single dose or in 2 divided doses.
Dosage Details
Oral
Benign prostatic hyperplasia
Adult: 8 mg daily as a single dose or in 2 divided doses, may be reduced based on patient’s condition.
Renal Impairment
CrCl (mL/min) Dosage
< 30 Contraindicated.
30-50 4 mg daily, may be adjusted to 8 mg daily after 1 week depending on patient response.
Hepatic Impairment
Severe (Child-Pugh class C): Contraindicated.
Administration
Should be taken with food.
Contraindications
Severe renal and hepatic impairment. Patient treated with CYP3A4 inhibitors and α-blockers.
Special Precautions
Patient with orthostatic hypotension. Patients undergoing cataract surgery. Prostate cancer should be ruled out prior to initiation of silodosin. Moderate renal and mild to moderate hepatic impairment. Not indicated for use in women and children.
Adverse Reactions
Significant: Orthostatic hypotension.
Cardiac disorders: Tachycardia.
Gastrointestinal disorders: Diarrhoea, abdominal pain, dry mouth.
Nervous system disorders: Dizziness, headache.
Psychiatric disorders: Insomnia.
Renal and urinary disorders: UTI.
Reproductive system and breast disorders: Abnormal ejaculation (e.g. retrograde ejaculation, decreased libido).
Respiratory, thoracic and mediastinal disorders: Nasopharyngitis, nasal congestion, influenza, sinusitis, rhinitis.
Patient Counseling Information
This drug may cause postural hypotension (with or without symptoms e.g. dizziness) and syncope, if affected, do not drive or operate machinery.
MonitoringParameters
Monitor blood pressure and urinary symptoms.
Overdosage
Symptoms: Postural hypotension. Management: Maintain patient in supine position. Induce vomiting or consider gastric lavage. Provide cardiovascular support if overdose leads to hypotension.
Drug Interactions
Silodosin plasma concentration may be increased by moderate CYP3A4 inhibitors (e.g. diltiazem, erythromycin, verapamil), P-glycoprotein transport inhibitors (e.g. ciclosporin) and uridine diphosphate-glucuronosyltransferase (e.g. fluconazole, probenecid, valproic acid). Concomitant use with antihypertensive agents may increase risk of adverse effect (orthostatic hypotension). Concomitant use with PDE-5 inhibitors (e.g. sildenafil) may lead to symptomatic hypotension.
Potentially Fatal: Significantly increased plasma concentration with strong CYP3A4 inhibitor (e.g. clarithromycin, itraconazole, ketoconazole, ritonavir). Additive cardiovascular effects with other α-adrenergic blockers.
Action
Description: Silodosin is a selective antagonist of post-synaptic α1-adrenoreceptors in the prostate and bladder. Blockade of α1-adrenoreceptors causes relaxation of smooth muscle resulting to improved urine flow and reduced BPH symptoms.
Pharmacokinetics:
Absorption: Rapidly absorbed. Bioavailability: Approx 32%. Time to peak plasma concentration: Approx 3 hours.
Distribution: Volume of distribution: 49.5 L. Plasma protein binding: Approx 97%.
Metabolism: Metabolised in the liver via glucuronidation (UGT2B7), alcohol and aldehyde dehydrogenase and oxidative pathways, primarily CYP3A4 to the main metabolite, KMD-3213G (glucuronide conjugate).
Excretion: Via faeces (55%) and urine (34%). Elimination half-life: Approx 13 hours (silodosin); approx 24 hours (KMD-3213G).
Chemical Structure

Chemical Structure Image
Silodosin

Source: National Center for Biotechnology Information. PubChem Database. Silodosin, CID=5312125, https://pubchem.ncbi.nlm.nih.gov/compound/Silodosin (accessed on Jan. 23, 2020)

Storage
Store below 30°C. Protect from light and moisture.
ATC Classification
G04CA04 - silodosin ; Belongs to the class of alpha-adrenoreceptor antagonists. Used in the treatment of benign prostatic hypertrophy.
References
Anon. Silodosin. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 21/05/2019.

Anon. Silodosin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 21/05/2019.

Buckingham R (ed). Silodosin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 21/05/2019.

Silodosin Capsule (Amneal Pharmaceuticals NY LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 21/05/2019.

Urief Fim-Coated Tablets 4 mg (Kissei Pharmaceutical Co., Ltd.). MIMS Malaysia. http://www.mims.com/malaysia. Accessed 30/05/2019.

Urorec 4mg Hard Capsules (Recordati Ireland Ltd.). European Medicines Agency [online]. Accessed 21/05/2019.

Disclaimer: This information is independently developed by MIMS based on Silodosin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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