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finasteride (Proscar, Propecia)

Tradenames: Proscar, Propecia. Indications: 1) benign prostatic hypertrophy (BPH) a) 5 mg PO QD b) induces regression of hyperplastic prostate tissue c) 2-6 months may be required before improvement of symptoms d) combination therapy finasteride + alpha blocker is no better than either agent alone e) efficacy in treatment of BPH generally confined to patients with a large prostate (40 mL) [4,6] 2) used in combination with other androgen antagonists for prostate cancer 3) lowers 7 year risk of prostate cancer 25% [11] - statistically insignificant decline in prostate cancer mortality [11] 4) hair growth/prevention of hair loss (androgenic alopecia) a) 1 mg PO QD b) 3-12 months before benefits seen c) may be inferior to dutasteride 5) hirsuitism Contraindications: - pregnancy - prostate cancer prophylaxis - see finasteride prophylaxis study - although finasteride lowers serum PSA by as much as 50%, it does not diminish risk of prostate cancer [6] - not useful for urge incontinence associated with benign prostatic hypertrophy Dosage: 1) 1-5 mg PO QD a) 1 mg PO QD for androgenic alopecia b) 5 mg PO QD for BPH 2) 10 mg PO QD for prostate cancer Tabs: 1 & 5 mg. Pharmacokinetics: 1) oral bioavailability is 64%, unaffected by food 2) metabolized by liver by cyt P450 3A4 to inactive compounds 3) metabolites excreted mainly in the bile Adverse effects: 1) impotence, erectile dysfunction (common [4]) 2) decreased libido may persist after discontinuation [7,8,12] 3) decreased volume of ejaculate 4) breast swelling 5) hypersensitivity 6) not a risk factor for high-grade prostate cancer [10] 7) depression, anxiety, suicide ideation [13] - men seeking treatment for alopecia have a higher prevalence of depression & sexual dysfunction than the general population, - FDA requires addition of suicidal ideation & behavior to adverse effects [13] Drug interactions: 1) any drug that inhibits cyt P450 3A4 may increase levels of finasteride 2) any drug that induces cyt P450 3A4 may diminish levels of finasteride Test interactions: - lowers prostate-specific antigen in serum (PSA) Laboratory: - finasteride in serum/plasma Mechanism of action: 1) inhibits testosterone 5-alpha reductase 2 which converts testosterone to dihydrotestosterone (DHT) 2) DHT is responsible for stimulation of prostatic growth 3) decreases prostate size (after several months) 4) diminishes risk of prostate cancer [5] Clinical trial: -> Proscar Long-Term Efficacy and Safety Study (PLESS)

Interactions

drug adverse effects of 5-alpha reductase inhibitors

Related

finasteride prophylaxis study

General

5-alpha reductase inhibitor

Properties

MISC-INFO: elimination route LIVER

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. http/www.propecia.com
  3. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  4. Medical Knowledge Self Assessment Program (MKSAP) 11, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2015, 2018, 2022.
  5. Prescriber's Letter 15(8): 2008 Finasteride (Proscar) Reduces Prostate Cancer Risk Detail-Document#: 240807 (subscription needed) http://www.prescribersletter.com
  6. Geriatric Review Syllabus, 7th edition Parada JT et al (eds) American Geriatrics Society, 2010 - Geriatric Review Syllabus, 8th edition (GRS8) Durso SC and Sullivan GN (eds) American Geriatrics Society, 2013
  7. FDA: Questions and Answers: Finasteride Label Changes http://www.fda.gov/Drugs/DrugSafety/InformationbyDrugClass/ucm299754.htm
  8. Prescriber's Letter 19(9): 2012 Finasteride (Propecia, Proscar) and Persistent Sexual Adverse Events Detail-Document#: 280923 (subscription needed) http://www.prescribersletter.com - Prescriber's Letter 20(3): 2013 Persistent Sexual Dysfunction with Finasteride and Dutasteride Detail-Document#: 290308 (subscription needed) http://www.prescribersletter.com
  9. Thompson IM Long-Term Survival of Participants in the Prostate Cancer Prevention Trial. N Engl J Med 2013; 369:603-610 PMID: 23944298 http://www.nejm.org/doi/full/10.1056/NEJMoa1215932 - LeFevre M A Role for Finasteride in the Prevention of Prostate Cancer? N Engl J Med 2013; 369:670-671August 15, 2013 PMID: 23944306 http://www.nejm.org/doi/full/10.1056/NEJMe1307059
  10. Unger JM, Hershman DL, Till C et al. Using Medicare claims to examine long-term prostate cancer risk of finasteride in the Prostate Cancer Prevention Trial. J Natl Cancer Inst 2018 Nov; 110:1208-1215. PMID: 29534197
  11. Goodman PJ, Tangen CM, Darke AK et al Long-Term Effects of Finasteride on Prostate Cancer Mortality. N Engl J Med 2019; 380:393-394 PMID: 30673548 https://www.nejm.org/doi/full/10.1056/NEJMc1809961
  12. Ho RS Ongoing Concerns Regarding Finasteride for the Treatment of Male-Pattern Androgenetic Alopecia. JAMA Dermatol. Published online November 11, 2020 PMID: 33175098 https://jamanetwork.com/journals/jamadermatology/fullarticle/2772815
  13. Kneisel K Renewed Concerns About Finasteride and Mental Health - Database study links popular alopecia treatment with increased risks of suicidality, depression. MedPage Today 2020-11-27 https://www.medpagetoday.org/dermatology/generaldermatology/89913 - Nguyen DD, et al Investigation of suicidality and psychological adverse events in patients treated with finasteride. JAMA Dermatol 2020. Nov 11 PMID: 33175100 PMCID: PMC7658800 https://jamanetwork.com/journals/jamadermatology/article-abstract/2772818 - Ho RS Ongoing Concerns Regarding Finasteride for the Treatment of Male-Pattern Androgenetic Alopecia. JAMA Dermatol. Published online November 11, 2020. PMID: 33175098 https://jamanetwork.com/journals/jamadermatology/article-abstract/2772815 - Levine D FDA Requires Disclosure of Suicide Risk for Anti-baldness Drug. Medscape. June 24, 2022 https://www.medscape.com/viewarticle/975401