Dutasteride is a synthetic 4-azasteroid compound that inhibits both Type 1 and Type 2 isoforms of the 5-alpha reductase enzyme, reducing serum dihydrotestosterone (DHT) by up to 94%. It was approved by the FDA in 2001 under the brand name Avodart for the treatment of bph/">benign prostatic hyperplasia (BPH) and is widely used off-label for androgenetic alopecia (pattern hair loss) in men and postmenopausal women.
What Is Dutasteride?
Dutasteride is a prescription medication in the 5-alpha reductase inhibitor (5ARI) drug class. It was developed by GlaxoSmithKline (GSK) and received FDA approval on November 20, 2001, for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate gland. Its chemical name is (5α,17β)-N-{2,5-bis(trifluoromethyl)phenyl}-3-oxo-4-azaandrost-1-ene-17-carboxamide, with a molecular formula of C₂₇H₃₀F₆N₂O₂.
Unlike finasteride, which blocks only the Type 2 isoform of 5-alpha reductase, dutasteride inhibits both Type 1 and Type 2 isoforms. This dual inhibition results in a more complete suppression of DHT, the androgen primarily responsible for prostate enlargement and androgenetic hair loss.
Brand Names and Availability
Dutasteride is available under several brand names worldwide:
- Avodart: the original brand name (GSK), available in the United States and globally
- Duagen: available in some European markets
- Avolve: available in select markets
- Duodart / Combodart: combination product containing dutasteride 0.5 mg + tamsulosin 0.4 mg, for BPH
Generic dutasteride (0.5 mg capsules) became available after patent expiration and is now widely accessible at significantly lower cost than the brand-name versions.
How Dutasteride Differs from Finasteride
Both dutasteride and finasteride belong to the 5ARI drug class, but they differ in important ways. Dutasteride blocks both Type 1 and Type 2 5-alpha reductase isoforms, while finasteride blocks only Type 2. This results in dutasteride reducing serum DHT by approximately 94%, against approximately 65% for finasteride at the 1 mg hair-loss dose and approximately 70% at the 5 mg BPH dose (PROPECIA and PROSCAR prescribing information, section 12.2). Dutasteride also has a significantly longer half-life (approximately 5 weeks versus about 5 to 6 hours for finasteride in men aged 18 to 60, and about 8 hours in men over 70), meaning it remains in the body much longer after discontinuation. Read the full dutasteride vs finasteride comparison.
FDA-Approved and Off-Label Uses
Dutasteride’s only FDA-approved indication is the treatment of symptomatic BPH. However, it is widely prescribed off-label for:
- Androgenetic alopecia (male pattern hair loss): the most common off-label use, supported by multiple clinical trials. Learn more
- Female pattern hair loss: used in postmenopausal women. Learn more
- Prostate cancer chemoprevention: studied in the REDUCE trial. Learn more
See all dutasteride uses · How dutasteride works · Dosage guide
Key Facts at a Glance
| Property | Detail |
|---|---|
| Drug class | 5-alpha reductase inhibitor (5ARI) |
| FDA approval | November 20, 2001 |
| Manufacturer | GlaxoSmithKline (GSK) |
| Standard dose | 0.5 mg oral capsule, once daily |
| DHT reduction | Up to 94% |
| Half-life | Approximately 5 weeks |
| Use in pregnancy | Contraindicated. Dutasteride can cause abnormal genital development in a male fetus (FDA label sections 4 and 8.1) |
| Available as generic | Yes |
Who Should Not Take Dutasteride
Dutasteride is contraindicated in:
- Women who are pregnant or may become pregnant. Dutasteride is contraindicated in pregnancy because it can cause abnormal genital development in a male fetus (FDA label sections 4 and 8.1)
- Children and adolescents
- Patients with known hypersensitivity to dutasteride, other 5ARIs, or any component of the formulation
- Patients with severe hepatic impairment (dutasteride is extensively metabolized by the liver)
Due to its long half-life, dutasteride remains in the body for months after discontinuation. Blood donation should be avoided for at least 6 months after the last dose to prevent exposure to pregnant transfusion recipients.
Sources
- FDA. Avodart (dutasteride) prescribing information. accessdata.fda.gov
- FDA. PROPECIA (finasteride) prescribing information. dailymed.nlm.nih.gov
- FDA. PROSCAR (finasteride) prescribing information. dailymed.nlm.nih.gov
- NCBI StatPearls. Dutasteride. ncbi.nlm.nih.gov
- MedlinePlus. Dutasteride. medlineplus.gov