5a-Reductase Inhibitor

Aka: 5a-Reductase Inhibitor, Finasteride, Proscar, Propecia, Dutasteride, Duagen, Avodart

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II. Indications

  1. Benign Prostatic Hyperplasia
    1. BPH-Associated Gross Hematuria
    2. Large Prostate size >40 ml (see PSA to estimate Prostate size)
  2. Androgenic Alopecia in males (Finasteride)
    1. Adjunct to hair transplantation

III. Mechanism

  1. Inhibits Testosterone to Dihydrotestosterone conversion
    1. Competitive inhibition of enzyme 5a-reductase
    2. Finasteride inhibits Type II 5a reductase
    3. Dutasteride inhibits both Type I and II 5a reductase
  2. Reduces volume of Prostate
  3. Improves urine blood flow

IV. Preparations

  1. Finasteride (Propecia, Proscar)
  2. Dutasteride (Avodart)

V. Dosing

  1. Alopecia
    1. Finasteride 1 mg orally daily (or one quarter tablet daily of the 5 mg tablet)
  2. Benign Prostatic Hyperplasia (typically used in combination with Tamsulosin or Terazosin)
    1. Finasteride 5 mg orally daily
    2. Dutasteride 0.5 mg orally daily

VI. Advantages: Finasteride

  1. Alopecia
    1. Increases Hair Growth and reduces Hair Loss
    2. Effective on vertex and anterior mid-scalp
    3. Side effects uncommon
  2. Benign Prostatic Hyperplasia
    1. May be more effective in men with large Prostate

VII. Disadvantages: Finasteride

  1. Alopecia
    1. Improvements take 6-12 months
    2. Any benefits are lost when medication is stopped
    3. Finasteride 1 mg tablet is much more expensive then 5 mg tablet
      1. Consider quartering the 5 mg tablet (generic, cheap) which drops the cost considerably
  2. Benign Prostatic Hyperplasia
    1. Increased urine flow not evident for 6-12 months
    2. Mediocre effects on obstructive symptoms and urine flow (better in Prostate size >40 ml)
      1. Less effective than alpha blockers (e.g. Hytrin)
      2. Less effective than surgery
      3. Only as effective as Saw Palmetto
    3. Highly effective in reducing BPH-related Gross Hematuria (80%)
      1. Kearney (2002) J Urol 167:2489-91 [PubMed]

VIII. Adverse Effects

  1. Decreased Libido or Erectile Dysfunction (2%)
    1. Longterm Erectile Dysfunction may persists even after stopping Finasteride in up to 0.1% of patients
    2. Irwig (2012) J Sex Med 9(11): 2927-32 [PubMed]
  2. Lowers Prostate Specific Antigen (PSA) Values by 30-50%
    1. Obtain PSA baseline prior to starting Finasteride
    2. Double the actual PSA to determine work-up
    3. Obtain baseline Digital Rectal Exam
  3. Longterm use associated with high grade Prostate Cancer
    1. Thompson (2003) N Engl J Med 349:215-24 [PubMed]

IX. References

  1. (1992) Med Lett Drugs Ther 34:83 [PubMed]
  2. Nickel (1996) CMAJ 155:1251-9 [PubMed]
  3. Guess (1996) J Urol 155:3-9 [PubMed]

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Related Studies

Cost: Medications

Finasteride (on 6/18/2017 at Walmart.com)
Finasteride 5mg #30 tablets for $9.00 $0.30 each
finasteride (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
FINASTERIDE 1 MG TABLET Generic $0.15 each
FINASTERIDE 5 MG TABLET Generic $0.10 each
proscar (on 6/8/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
PROSCAR 5 MG TABLET Generic $0.10 each
propecia (on 6/8/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
PROPECIA 1 MG TABLET Generic $0.15 each
dutasteride (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
DUTASTERIDE 0.5 MG CAPSULE Generic $0.30 each
DUTASTERIDE-TAMSULOSIN 0.5-0.4 Generic $3.41 each
avodart (on 2/22/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
AVODART 0.5 MG SOFTGEL Generic $0.30 each
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information.

Ontology: Finasteride (C0060389)

Definition (MSH) An orally active 3-OXO-5-ALPHA-STEROID 4-DEHYDROGENASE inhibitor. It is used as a surgical alternative for treatment of benign PROSTATIC HYPERPLASIA.
Definition (NCI) A synthetic 4-azasteroid compound. Finasteride competitively binds to and inhibits steroid type II 5-alpha-reductase in the prostate gland, liver, and skin, thereby interfering with the enzymatic conversion of testosterone to 5-dihydrotestosterone (DHT) and reducing serum DHT levels. The reduction in serum DHT levels results in diminished stimulation of androgen receptors in the nuclei of prostate cells and, so, diminished prostate cell proliferation.
Definition (NCI_NCI-GLOSS) A drug used to reduce the amount of male hormone (testosterone) produced by the body.
Definition (CSP) orally active testosterone 5-alpha reductase inhibitor, used as an alternative to surgery for treatment of benign prostatic hyperplasia.
Definition (PDQ) A synthetic 4-azasteroid compound. Finasteride competitively binds to and inhibits steroid type II 5-alpha-reductase in the prostate gland, liver, and skin, thereby interfering with the enzymatic conversion of testosterone to 5-dihydrotestosterone (DHT) and reducing serum DHT levels. The reduction in serum DHT levels results in diminished stimulation of androgen receptors in the nuclei of prostate cells and, so, diminished prostate cell proliferation. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=41096&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=41096&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C1099" NCI Thesaurus)
Concepts Hormone (T125) , Pharmacologic Substance (T121) , Steroid (T110)
MSH D018120
SnomedCT 109035006, 386963006
LNC LP101034-9, MTHU036233
English Finasteride, 4-Azaandrost-1-ene-17-carboxamide, N-(1,1-dimethylethyl)-3-oxo-, (5alpha,17beta)-, (5alpha,17beta)-N-(1,1-Dimethylethyl)-3-oxo-4-azaandrost-1-ene-17-carboxamide, finasteride, finasteride (medication), FINASTERIDE, Finasteride [Chemical/Ingredient], finasteride products, Finasteride (product), Finasteride (substance)
Swedish Finasterid
Czech finasterid
Finnish Finasteridi
Russian FINASTERID, ФИНАСТЕРИД
Japanese フィナステリド
Polish Finasteryd
Spanish Finasteride, finasterida (producto), finasterida (sustancia), finasterida, Finasterida
Portuguese Finasteride, Finasterida
French Finastéride
German Finasterid
Italian Finasteride
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Proscar (C0678149)

Concepts Pharmacologic Substance (T121) , Steroid (T110)
MSH D018120
English finasteride (Proscar), proscar, Proscar, Cahill May Roberts Brand of Finasteride, MSD Chibropharm Brand of Finasteride, Merck Brand 2 of Finasteride, Merck Frosst Brand 2 of Finasteride, Merck Sharp & Dhome Brand 2 of Finasteride
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Propecia (C0722858)

Concepts Steroid (T110) , Pharmacologic Substance (T121)
MSH D018120
English finasteride (Propecia), propecia, Propecia, Propeshia, MSD Brand of Finasteride, Merck Brand 1 of Finasteride, Merck Frosst Brand 1 of Finasteride, Merck Sharp & Dohme Brand 1 of Finasteride
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Dutasteride (C0754659)

Definition (NCI) A synthetic 4-azasteroid compound. Dutasteride competitively and specifically binds to isoenzymes 1 and 2 of 5 alpha-reductase, forming stable enzyme complexes and inhibiting the conversion of testosterone to 5 alpha-dihydrotestosterone (DHT); the reduction in DHT activity may mitigate or prevent enlargement of the prostate gland. The type 2 5 alpha-reductase isoenzyme is primarily active in the reproductive tissues, while the type 1 isoenzyme is also active in skin and the liver.
Definition (NCI_NCI-GLOSS) A drug used to treat symptoms of an enlarged prostate gland. It is being studied in the treatment of male hair loss and prostate cancer. Avodart blocks enzymes the body needs to make male sex hormones. It is a type of 5-alpha reductase inhibitor.
Definition (PDQ) A synthetic 4-azasteroid compound. Dutasteride competitively and specifically binds to isoenzymes 1 and 2 of 5-alpha-reductase, forming stable enzyme complexes and inhibiting the conversion of testosterone to 5-alpha-dihydrotestosterone (DHT); the reduction in DHT activity may mitigate or prevent enlargement of the prostate gland. The type 2 5-alpha-reductase isoenzyme is primarily active in the reproductive tissues, while the type 1 isoenzyme is also active in skin and the liver. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=479183&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=479183&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C47503" NCI Thesaurus)
Concepts Steroid (T110) , Pharmacologic Substance (T121)
MSH C108373
SnomedCT 408009000, 385570006, 385572003
English DUTASTERIDE @ @ UNIDENTIFIED, DUTASTERIDE UNIDENTIFIED, alpha,alpha,alpha,alpha',alpha',alpha'-Hexafluoro-3-oxo-4-aza-5alpha-androst-1-ene-17beta-carboxy-2',5'-xylidide, Avolve,(5alpha,17beta)-N-(2,5-Bis(trifluoromethyl)phenyl)-3-oxo-4-azaandrost-1-ene-17-carboxamide, 17beta-N-(2,5-bis(trifluoromethyl))phenyl-carbamoyl-4-aza-5alpha-androst-1-en-3-one, dutasteride (medication), DUTASTERIDE, dutasteride [Chemical/Ingredient], Dutasteride, Dutasteride (product), Dutasteride (substance), dutasteride
Spanish dutasterida (producto), dutasterida (sustancia), dutasterida
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: 5-alpha Reductase Inhibitor [EPC] (C1318898)

Concepts Pharmacologic Substance (T121)
English 5-alpha Reductase Inhibitor, 5-alpha Reductase Inhibitor [EPC]
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Pharmacology

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