DUTASTERIDE
Clinical safety rating: avoid
Contraindicated (not allowed)
Competitive inhibitor of type II and type I 5α-reductase isoenzymes, blocking conversion of testosterone to dihydrotestosterone (DHT) in prostate, hair follicles, and other tissues.
| Metabolism | Extensively metabolized in liver via CYP3A4 and CYP1A2; minor metabolism by CYP2C8, CYP2C9, CYP2C19, and CYP2D6. |
| Excretion | Primarily fecal (70%) as metabolites; renal excretion accounts for <5% unchanged drug. |
| Half-life | Terminal half-life approximately 3-4 weeks (21-35 days) in young adults; 5-6 weeks in elderly; supports once-daily dosing due to slow elimination. |
| Protein binding | >99% bound to albumin and alpha-1 acid glycoprotein; high affinity. |
| Volume of Distribution | Approximately 300-500 L (3-5 L/kg), indicating extensive tissue distribution, particularly to prostate and seminal vesicles. |
| Bioavailability | Oral: Approximately 60% (range 40-80%) with food; not administered parenterally. |
| Onset of Action | Oral: Clinical effect (reduction in serum DHT) observed within 1 week; maximal effect on prostate volume at 6-12 months. |
| Duration of Action | Prolonged due to slow elimination; effect persists for 6-12 months after discontinuation due to tissue binding. |
0.5 mg orally once daily.
| Dosage form | CAPSULE |
| Renal impairment | No dose adjustment required for renal impairment (including dialysis). |
| Liver impairment | Contraindicated in Child-Pugh Class C; use with caution in mild to moderate impairment (Child-Pugh A/B) with no specific dose adjustment established. |
| Pediatric use | Not indicated in pediatric patients; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment required; monitor for adverse effects (e.g., dizziness, orthostatic hypotension) due to age-related comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Strong CYP3A4 inhibitors may increase levels Pregnant women should not handle crushed capsules due to risk of fetal abnormality.
| Breastfeeding | No data on dutasteride in human milk. M/P ratio unknown. Dutasteride is highly lipophilic and likely excreted in breast milk. Because of potential adverse effects on the nursing infant (e.g., interference with androgen-mediated development in male infants), breastfeeding is contraindicated during therapy and for at least 6 months after the last dose due to long half-life (approximately 5 weeks). |
| Teratogenic Risk | Dutasteride is contraindicated in pregnancy. It is a 5α-reductase inhibitor that can inhibit the conversion of testosterone to dihydrotestosterone (DHT), potentially causing abnormal development of external genitalia in male fetuses. Risk extends throughout all trimesters due to potential disruption of androgen-mediated development in male fetuses during the first trimester and cumulative effects from drug accumulation in adipose tissue. No adequate human studies exist; animal studies show teratogenicity in male offspring at clinically relevant doses. |
■ FDA Black Box Warning
No FDA black box warning.
| Common Effects | Impotence Decreased libido Ejaculation disorder Orthostatic hypotension sudden lowering of blood pressure on standing Breast enlargement in male Breast tenderness in male |
| Serious Effects |
["Women of childbearing potential (pregnancy category X; risk of fetal harm due to inhibition of 5α-reductase)","History of hypersensitivity to dutasteride or other 5α-reductase inhibitors","Pediatric patients"]
| Precautions | ["Risk of high-grade prostate cancer in men aged 50-79 with elevated PSA and previous negative biopsy (see PLCO trial)","Increased risk of sexual adverse events (impotence, decreased libido, ejaculation disorders) that may persist after discontinuation","Elevated PSA levels: use caution when interpreting PSA values; establish new baseline after 6 months of treatment"] |
Loading safety data…
| Fetal Monitoring | If exposure occurs, assess pregnancy status. Monitor fetal development via ultrasound for potential genital anomalies in male fetuses. No specific maternal monitoring required; routine prenatal care. Dutasteride is not indicated for women; any inadvertent exposure warrants pregnancy counseling and follow-up. |
| Fertility Effects | Dutasteride may decrease sperm count, semen volume, and sperm motility, potentially impairing male fertility. Effects are reversible upon discontinuation. No direct female fertility data; as a 5α-reductase inhibitor, it could theoretically affect ovarian function, but evidence is lacking. Treatment of male partners with dutasteride does not appear to harm female fertility or pregnancy outcomes from limited studies. |