Women of child-bearing potential or who are pregnant should not handle crushed or broken tab. Excreted in semen therefore use of condom is recommended.
Monitoring Parameters
Rule out other urological diseases (e.g. prostate cancer) before initiation of therapy. Perform digital rectal examination and other assessment for prostate cancer before and during therapy. Obtain new baseline prostate-specific antigen (PSA) level after ≥6 months of treatment then monitor periodically thereafter. Monitor for psychiatric symptoms, objective and subjective signs of relief of benign prostatic hyperplasia (e.g. improvement in urinary flow, reduction in symptoms of urgency, relief of difficulty in micturition).
Lab Interference
Decreases serum PSA level by approx 50% within 6 months of use.
Action
Description: Mechanism of Action: Finasteride, a 4-azasteroid, is a competitive inhibitor of type II 5-α reductase. This results in the suppression of the conversion of testosterone to dihydrotestosterone, leading to significantly decreased serum dihydrotestosterone (DHT) levels. In male-pattern baldness, finasteride decreases scalp DHT levels found in hairy scalp thus increases hair regrowth and slows hair loss. Duration: Prostate volume reverts to baseline within approx 3 months after stopping treatment (benign prostatic hyperplasia); reversal of effect within 12 months of stopping treatment (male-pattern baldness). Pharmacokinetics: Absorption: Bioavailability: Approx 63-80%. Time to peak plasma concentration: 1-2 hours. Distribution: Crosses the blood-brain barrier and detected in the seminal fluid (small amounts). Volume of distribution: 76 L. Plasma protein binding: Approx 90%. Metabolism: Extensively metabolised in the liver by CYP3A4 into 2 active metabolites. Excretion: Via faeces (57%); urine (39%, as metabolites). Elimination half-life: Approx 5-6 hours.
Chemical Structure
Finasteride Source: National Center for Biotechnology Information. PubChem Database. Finasteride, CID=57363, https://pubchem.ncbi.nlm.nih.gov/compound/Finasteride (accessed on Jan. 21, 2020)
Storage
Store below 30°C. Protect from light and moisture.
D11AX10 - finasteride ; Belongs to the class of other dermatologicals. G04CB01 - finasteride ; Belongs to the class of testosterone-5-alpha reductase inhibitors. Used in the treatment of benign prostatic hypertrophy.
References
Anon. Finasteride. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 29/01/2021.Buckingham R (ed). Finasteride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 29/01/2021.Finasteride 1 mg Tablet, Film Coated (Accord Healthcare, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 29/01/2021.Finasteride 1 mg Tablets (Dr Reddy’s Laboratories [UK] Ltd). MHRA. https://products.mhra.gov.uk. Accessed 01/02/2021.Finasteride 5 mg Tablet, Film Coated (Accord Healthcare, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 02/02/2021.Finasteride 5 mg Tablets (Dr Reddy’s Laboratories [UK] Ltd). MHRA. https://products.mhra.gov.uk. Accessed 29/01/2021.Organon New Zealand Limited. Propecia 1 mg Film Coated Tablets data sheet 1 December 2020. Medsafe. http://www.medsafe.govt.nz. Accessed 29/01/2021.Proscar 5 mg Tablet (Merck Sharp & Dohme [Malaysia] Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 02/02/2021.Rex Medical Limited. Ricit 5 mg Film Coated Tablets data sheet 5 May 2017. Medsafe. http://www.medsafe.govt.nz. Accessed 02/02/2021.
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