Carbamazepine
Moderate
Textbook
Reduced plasma levels and potentially decreased efficacy of dutasteride.
Interactions with CYP3A4 inducers are possible; dose adjustments or monitoring may be required.
Source: KDT 7e · p303
Drug reference
Dutasteride
5-alpha-reductase inhibitor (type 1 and 2) · Benign Prostatic Hyperplasia agent; Androgen inhibitor
Also known as Avodart, Dutasterid
START
0.5 mg PO once daily (± tamsulosin 0.4 mg)
TYPICAL MAX
0.5 mg/day
STOP IF
Significant depression/suicidality, suspected breast malignancy, planned conception (long washout)
WATCH
PSA — establish new baseline at 6 months and double measured PSA when screening; mood; sexual function
CDSCO approvedSchedule HATC G04CB02
KDIGO 2024 + manufacturer label
- ONSET
- 38min · absorption onset
- PEAK
- 2.5h · Cmax
- t½
- 5w · steady-state t½ (~5 weeks)
- DURATION
- 1d · once-daily dosing
EXCRETION
Hepatic CYP3A4; faecal metabolites, negligible renal
route + CYP
INTERACTIONS
—
none in our sources
PREGNANCY
Contraindicated — risk of male-fetus genital abnormalities; women must not handle leaking capsules
FDA category + note
Available in India
50 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Dual inhibition of 5-alpha-reductase types 1 and 2, blocking conversion of testosterone to dihydrotestosterone (>90% serum DHT suppression), reducing prostate volume and androgenetic hair loss.
Indications
Symptomatic benign prostatic hyperplasia (alone or with tamsulosin)Androgenetic alopecia (off-label/region-dependent)
Dosing
- Adult
- 0.5 mg PO once daily (monotherapy or with tamsulosin 0.4 mg).
- Pediatric
- Contraindicated.
- Renal adjustment
- No adjustment (minimal renal excretion).
- Hepatic adjustment
- No data in hepatic impairment — use with caution (extensive hepatic metabolism).
- Geriatric
- No specific adjustment.
- Max dose
- 0.5 mg/day
Pharmacokinetics
Onset
DHT suppression within days; clinical benefit 3–6 months
Peak effect
~2–3 h (Cmax); clinical 6 months
Duration
Long (accumulates)
Half-life
~5 weeks at steady state
Bioavailability
~60%
Protein binding
>99%
Metabolism
Hepatic CYP3A4/3A5
Excretion
Faecal (metabolites); negligible renal unchanged
Contraindications
- Pregnancy and women of childbearing potential (teratogenic — male fetus)
- Children
- Hypersensitivity to dutasteride or other 5-ARIs
Side effects
Common
Decreased libidoErectile dysfunctionEjaculation disordersGynaecomastia/breast tenderness
Serious
- Persistent sexual dysfunction (may continue after stopping)
- Depressed mood/suicidality (reported)
- Possible increased high-grade prostate cancer (class signal)
- Male breast cancer (rare)
Pregnancy & lactation
Pregnancy
Contraindicated — risk of male-fetus genital abnormalities; women must not handle leaking capsules
Lactation
Not indicated in women
Drug interactions
Ketoconazole
Moderate
Database
Increased plasma levels and potential for adverse effects of dutasteride.
Interactions with CYP3A4 inhibitors are possible; dose adjustments or monitoring may be required.
Source: DDInter
Strong Cyp3a4 Inhibitors
Moderate
Database
Increased dutasteride exposure
Consider dose interval reduction with long-term potent inhibitors
Source: Kimi deep-research + Cla
Tamsulosin
Moderate
Database
Intended combination — additive BPH benefit; additive hypotension/ejaculatory effects
Standard combination; counsel on orthostasis/IFIS
Source: Kimi deep-research + Cla
Testosterone
Moderate
Database
Opposing hormonal effect; confounds therapy
Avoid concurrent unless clinically justified
Source: Kimi deep-research + Cla
7 additional low-confidence interactions hidden — those rows lack a documented mechanism or management plan in our sources.
Related guidelines
Ask House about Dutasteride
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Katzung, BNF·Verified: 2026-05-19 · House clinical team·Cockpit curated: 2026-05-19