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. Suicidal Ideation
    1. Irwig (2012) J Clin Psychiatry 73(9):1220-3 +PMID: 22939118 [PubMed]
  2. 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]
  3. 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
  4. Longterm use associated with high grade Prostate Cancer
    1. Thompson (2003) N Engl J Med 349:215-24 [PubMed]

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Cost: Medications

finasteride (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
FINASTERIDE 1 MG TABLET Generic $0.04 each
FINASTERIDE 5 MG TABLET Generic $0.06 each
propecia (on 10/19/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
PROPECIA 1 MG TABLET Generic $0.04 each
dutasteride (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
DUTASTERIDE 0.5 MG CAPSULE Generic $0.19 each
DUTASTERIDE-TAMSULOSIN 0.5-0.4 Generic $2.02 each
avodart (on 11/4/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
AVODART 0.5 MG SOFTGEL Generic $0.19 each