What is the use of Dutasteride (Avodart)?

From the Guidelines

Dutasteride is a medication primarily used to treat benign prostatic hyperplasia (BPH) by inhibiting the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), thereby reducing prostate size and improving urinary symptoms. The standard dose is 0.5 mg taken once daily with or without food. For BPH, dutasteride works by reducing the size of the prostate, increasing peak urinary flow rate, and reducing BPH symptoms 1. Treatment typically requires 3-6 months before maximum benefits are observed, and it should be continued long-term for sustained results. Common side effects include decreased libido, erectile dysfunction, ejaculation disorders, and breast tenderness or enlargement. Dutasteride is contraindicated in women, especially those who are pregnant or may become pregnant, as it can cause birth defects. It's also not recommended for men planning to father children soon, as it can affect sperm characteristics. Blood donation should be avoided during treatment and for 6 months after stopping. Regular PSA monitoring is important, as dutasteride reduces PSA levels by approximately 50%, which physicians need to account for when screening for prostate cancer 1.

Key Points

• Dutasteride is used to treat BPH by reducing prostate size and improving urinary symptoms
• The standard dose is 0.5 mg taken once daily with or without food
• Treatment requires 3-6 months before maximum benefits are observed and should be continued long-term
• Common side effects include decreased libido, erectile dysfunction, and breast tenderness or enlargement
• Dutasteride is contraindicated in women, especially those who are pregnant or may become pregnant

Mechanism of Action

Dutasteride inhibits the enzyme 5-alpha-reductase, which converts testosterone to dihydrotestosterone (DHT), thereby reducing prostate size and improving urinary symptoms 1. This leads to a reduction in androgenic growth and an increase in apoptosis and atrophy, shrinking the organ from 15-25% at six months. Atrophy is most pronounced in the glandular epithelial component of the prostate, the source of production and release of serum PSA, reducing levels by approximately 50% 1.

Clinical Use

Dutasteride is effective in partially relieving symptoms of BPH, but is less effective for this purpose than alpha-blocker therapy 1. However, due to the more progressive nature of the disease in men with larger glands and/or higher PSA values, conservatively treated patients face an increasingly worse prognosis, enhancing the difference over time in outcomes between dutasteride and no treatment or placebo groups. Dutasteride reduces the risk of subsequent acute urinary retention and the need for BPH-related surgery with the absolute benefit increasing with rising prostate volume or serum PSA 1.

From the FDA Drug Label

Dutasteride capsules are indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to: improve symptoms, reduce the risk of acute urinary retention (AUR), and reduce the risk of the need for BPH-related surgery. Dutasteride capsules in combination with the alpha-adrenergic antagonist, tamsulosin, are indicated for the treatment of symptomatic BPH in men with an enlarged prostate.

The use of Dutasteride (Avodart) is for the treatment of:

• Symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate
• Improving symptoms
• Reducing the risk of acute urinary retention (AUR)
• Reducing the risk of the need for BPH-related surgery It can be used alone or in combination with an alpha-adrenergic antagonist, such as tamsulosin 2.

From the Research

Use of Dutasteride (Avodart)

• Dutasteride (Avodart) is a potent, selective, irreversible inhibitor of type 1 and type 2 5alpha-reductase (5AR), used in the treatment of moderate to severe symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate 3.
• The primary use of dutasteride is to improve symptoms, reduce the risk of acute urinary retention (AUR), and decrease the need for BPH-related surgery 3, 4.
• Dutasteride has been shown to improve urinary symptoms, decrease total prostate volume (TPV), and reduce the risk of AUR and BPH-related surgery in men with moderate to severe symptoms of BPH and prostate enlargement 3.

Mechanism of Action

• Dutasteride inhibits both type 1 and type 2 isozymes of 5alpha-reductase, the enzyme responsible for converting testosterone to dihydrotestosterone (DHT) in the prostate and other tissues 5, 4.
• The inhibition of 5alpha-reductase leads to a decrease in DHT levels, resulting in a reduction in prostate volume and an improvement in urinary symptoms 5, 6.

Efficacy and Safety

• Dutasteride has been shown to be effective in reducing the risk of prostate cancer in at-risk men, although the clinical significance of this finding is still being debated 5, 7.
• The combination of dutasteride and tamsulosin has been shown to be well-tolerated and effective in improving BPH-related symptoms, peak urinary flow, and BPH-related health status 3.
• Common side effects of dutasteride include decreased libido, erectile dysfunction, ejaculation disorders, and gynecomastia 5, 6.