5α-reductase inhibitors
Finasteride vs Dutasteride
The table compares the compounds’ key data from their entry pages. Open each compound’s full entry for details. Educational content, not medical advice.
| Finasteride (Propecia / Proscar) | Dutasteride (Avodart) | |
|---|---|---|
| What it is | Selective type-II 5α-reductase inhibitor. FDA-approved (Proscar 1992 BPH 5 mg, Propecia 1997 AGA 1 mg). In AAS: scalp DHT suppression to slow hair loss in genetically predisposed users. Type-I 5AR not inhibited. | Dual 5α-reductase inhibitor (type-I + type-II). FDA-approved (2001 GSK) for BPH. In AAS: ~90% scalp DHT + acne reduction. Long t1/2 ~5 weeks – washout ~6 months. Higher PFS risk vs finasteride. |
| Mechanism | Selective type-II 5α-reductase inhibitor, ~70% scalp DHT suppression at 1 mg/day | Dual 5α-reductase inhibitor (type-I + type-II), ~90% scalp DHT suppression at 0.5 mg/day |
| Dosing (AAS hair-loss prevention) | 1 mg/day (Propecia) continuous during cycle | — |
| Half-life | ~6 h parent, pharmacodynamic effect 24+ h enzyme inhibition | ~5 weeks (very long, steady-state ~6 months, washout ~6 months) |
| Onset | DHT reduction measurable 24 h, hair stabilization 3-6 months | DHT reduction measurable 1 week, hair stabilization 3-6 months |
| Legal status | FDA + EMA Rx, HU + PL approved, WADA allowed (not 5AR-banned) | FDA + EMA Rx (BPH), HU + PL approved, off-label AGA US/EU, WADA allowed |
| Dosing (AAS hair-loss + acne) | — | 0.5 mg/day continuous or every other day (cost-saving) |
| Full entry | Open → | Open → |
What it is
Finasteride (Propecia / Proscar)Selective type-II 5α-reductase inhibitor. FDA-approved (Proscar 1992 BPH 5 mg, Propecia 1997 AGA 1 mg). In AAS: scalp DHT suppression to slow hair loss in genetically predisposed users. Type-I 5AR not inhibited.
Dutasteride (Avodart)Dual 5α-reductase inhibitor (type-I + type-II). FDA-approved (2001 GSK) for BPH. In AAS: ~90% scalp DHT + acne reduction. Long t1/2 ~5 weeks – washout ~6 months. Higher PFS risk vs finasteride.
Mechanism
Finasteride (Propecia / Proscar)Selective type-II 5α-reductase inhibitor, ~70% scalp DHT suppression at 1 mg/day
Dutasteride (Avodart)Dual 5α-reductase inhibitor (type-I + type-II), ~90% scalp DHT suppression at 0.5 mg/day
Dosing (AAS hair-loss prevention)
Finasteride (Propecia / Proscar)1 mg/day (Propecia) continuous during cycle
Dutasteride (Avodart)—
Half-life
Finasteride (Propecia / Proscar)~6 h parent, pharmacodynamic effect 24+ h enzyme inhibition
Dutasteride (Avodart)~5 weeks (very long, steady-state ~6 months, washout ~6 months)
Onset
Finasteride (Propecia / Proscar)DHT reduction measurable 24 h, hair stabilization 3-6 months
Dutasteride (Avodart)DHT reduction measurable 1 week, hair stabilization 3-6 months
Legal status
Finasteride (Propecia / Proscar)FDA + EMA Rx, HU + PL approved, WADA allowed (not 5AR-banned)
Dutasteride (Avodart)FDA + EMA Rx (BPH), HU + PL approved, off-label AGA US/EU, WADA allowed
Dosing (AAS hair-loss + acne)
Finasteride (Propecia / Proscar)—
Dutasteride (Avodart)0.5 mg/day continuous or every other day (cost-saving)