Dutasteride

What it is and how it works

Mechanism of Action Dutasteride inhibits the conversion of testosterone to DHT. DHT is the androgen primarily responsible for the initial development and subsequent enlargement of the prostate gland. Testosterone is converted to DHT by the enzyme 5 alpha-reductase, which exists as 2 isoforms, type 1 and type 2. The type 2 isoenzyme is primarily active in the reproductive tissues, while the type 1 isoenzyme is also responsible for testosterone conversion in the skin and liver. Dutasteride is a competitive and specific inhibitor of both type 1 and type 2 5 alpha-reductase isoenzymes, with which it forms a stable enzyme complex.

Mechanism class: 5-alpha Reductase Inhibitors

Indications

Dutasteride capsules is a 5 alpha-reductase inhibitor 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, and reduce the risk of the need for BPH-related surgery. Dutasteride capsules in combination with the alpha-adrenergic antagonist, tamsulosin, is indicated for the treatment of symptomatic BPH in men with an enlarged prostate. Limitations of Use: Dutasteride capsules is not approved for the prevention of prostate cancer. Monotherapy 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. Combination with Alpha-adrenergic Antagonist Dutasteride capsules in combination with the alpha-adrenergic antagonist, tamsulosin, is indicated for the treatment of symptomatic BPH in men with an enlarged prostate.

Dosage and administration (summary)

The capsules should be swallowed whole and not chewed or opened, as contact with the capsule contents may result in irritation of the oropharyngeal mucosa. Dutasteride capsules may be administered with or without food. Monotherapy: 0.5 mg once daily. Combination with tamsulosin: 0.5 mg once daily and tamsulosin 0.4 mg once daily. Dosing considerations: Swallow whole. May take with or without food. Monotherapy The recommended dose of dutasteride is 1 capsule (0.5 mg) taken once daily. Combination with Alpha-adrenergic Antagonist The recommended dose of dutasteride is 1 capsule (0.5 mg) taken once daily and tamsulosin 0.4 mg taken once daily.

Contraindications

Dutasteride capsules are contraindicated for use in: Pregnancy. Dutasteride use is contraindicated in women who are pregnant. In animal reproduction and developmental toxicity studies, dutasteride inhibited development of male fetus external genitalia. Therefore, dutasteride may cause fetal harm when administered to a pregnant woman. .

Warnings and precautions

Dutasteride capsules reduce serum prostate-specific antigen (PSA) concentration by approximately 50%. However, any confirmed increase in PSA while on dutasteride capsules may signal the presence of prostate cancer and should be evaluated, even if those values are still within the normal range for untreated men. Dutasteride capsules may increase the risk of high-grade prostate cancer. ( 5.2 , 6.1 ) Prior to initiating treatment with dutasteride capsules, consideration should be given to other urological conditions that may cause similar symptoms.

Pregnancy

Pregnancy Risk Summary Dutasteride is contraindicated for use in pregnancy because it may cause harm to the male fetus . Dutasteride is not indicated for use in women. Dutasteridem is a 5 alpha-reductase inhibitor that prevents conversion of testosterone to dihydrotestosterone (DHT), a hormone necessary for normal development of male genitalia.

Storage and supply

Dutasteride Capsules 0.5 mg are opaque, yellow, oblong shape capsules imprinted with “PC23” in red ink, packaged in bottles of 60 (NDC 68071-3757-6) with child-resistant closures. Store at 25°C (77°F); excursions permitted to 15º to 30ºC (59º to 86ºF) . Dutasteride is absorbed through the skin.

Source: Dutasteride (Dutasteride) — US FDA prescribing information, 2025-01-03, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.