Dutasteride

Dutasteride, sold under the brand name Avodart among others, is a medication primarily used to treat the symptoms of a benign prostatic hyperplasia (BPH), an enlarged prostate not associated with cancer. A few months may be required before benefits occur. It is also used for pattern hair loss in men and as a part of hormone therapy in transgender women. It i

Dutasteride, sold under the brand name Avodart among others, is a medication primarily used to treat the symptoms of a benign prostatic hyperplasia (BPH), an enlarged prostate not associated with cancer. A few months may be required before benefits occur.[5] It is also used for pattern hair loss in men and as a part of hormone therapy in transgender women.[6][7] It is usually taken by mouth.[8][9][5]

The most commonly reported side effects of dutasteride, although rare, include sexual dysfunction. In the largest available study of 6,729 men with BPH, 9% experienced erectile dysfunction (compared to 5.7% treated with a placebo), 3.3% experienced decreased sex drive (vs 1.6% of placebo), and 1.9% had enlarged breasts (vs 1% of placebo).[10][11] Exposure during pregnancy is specifically contraindicated because antiandrogens such as dutasteride have been shown to interfere with the sexual development of male fetuses.[3][8]

Dutasteride was patented in 1993 by Glaxo Wellcome (later known as GSK after additional mergers) and was approved for medical use in 2001.[12][8] In the United States and elsewhere, it is available as a generic medication.[5] In 2023, it was the 236th most commonly prescribed medication in the US with more than 1 million prescriptions.[13]

Medical uses

Benign prostatic hyperplasia and prostate cancer

Dutasteride is used for treating BPH, colloquially known as an "enlarged prostate".[9][14] It is approved by the Food and Drug Administration (FDA) in the U.S. for this indication.[15] A 2010 Cochrane review found a 25–26% reduction in the risk of developing prostate cancer with 5α-reductase inhibitor chemoprevention.[16]

Scalp hair loss and excessive hair growth

Dutasteride is approved for the treatment of male androgenetic alopecia in South Korea and Japan at a dosage of 0.5 mg per day.[6][17] Several studies have found it to induce hair regrowth in men more rapidly and to a greater extent than even the highest approved dosage of finasteride.[6][18][19][20] The superior effectiveness of dutasteride relative to finasteride for this indication is because the inhibition of 5α-reductase and consequent reduction of dihydrotestosterone (DHT) production within the hair follicles is more complete with dutasteride. Dutasteride is also used off-label in the treatment of female pattern hair loss.[21][22]

Other 5α-reductase inhibitors such as finasteride (a type 2 inhibitor) have been used off-label to treat excessive hair growth in women with hirsutism.[3][23] Since dutasteride is an inhibitor of both type 1 and 2 5α-reductases, it could theoretically be a more effective therapy for hirsutism. However, dutasteride is not recommended for this indication due to a lack of supportive clinical evidence and a substantial risk of birth defects in female patients who inadvertently become pregnant.[23][24]

Transgender hormone therapy

Dutasteride is sometimes used as a component of hormone therapy for transgender women in combination with an estrogen and/or another antiandrogen such as spironolactone.[7] It may be useful for preventing and treating scalp hair loss and can also be used as a general antiandrogen for those who have issues tolerating spironolactone, though as a α-reductase inhibitor it has limited effects compared to AR antagonists.[7]

Available forms

Dutasteride is provided in the form of soft, oil-filled gelatin capsules containing 0.5 mg dutasteride each.[25]

Contraindications

Women who are or who may become pregnant should not handle the drug. Dutasteride can cause birth defects in male fetuses, specifically ambiguous genitalia and undermasculinization.[25][26] This is due to its antiandrogenic effects similar to what is seen in 5α-reductase deficiency.[26] For the same reason, women who are currently pregnant should never take dutasteride.[25] People taking dutasteride should not donate blood to prevent birth defects if a pregnant woman receives blood and should also not donate blood for at least 6 months after the cessation of treatment due to the drug's long elimination half-life.[25]

Children and people with known significant hypersensitivity (e.g., serious skin reactions, angioedema) to dutasteride should not take it.[25]