5a-reductase, the enzyme responsible for converting testosterone to dihydrotestosterone, exists in 2 forms: Type 1 and Type 2. Finasteride selectively inhibits Type 2 (70%) whereas dutasteride inhibits both forms, (93%).
This is significant because dihydrotestosterone is thought to be important in the development of BPH; its suppression by these 2 agents may prove to be beneficial for patients with BPH.
Comparison of Clinical Trials With Finasteride and Dutasteride
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472914/pdf/RIU006009_0S31.pdf
Results of a phase II, double-blind, placebo-controlled, comparative dose-ranging trial of dutasteride and finasteride clearly demonstrated that serum DHT suppression was significantly greater with dutasteride (0.5 mg daily) than with finasteride (5 mg daily).3 The mean reduction in base-line DHT concentration in patients receiving 0.5 mg dutasteride daily was 94.7 ± 3.3% and for patients receiving finasteride 5 mg daily was 70.8 ± 18.3%, respectively (P < .001) (Figure 2). In non-comparative clinical trials, chronic therapy with dutasteride (0.5 mg daily) for up to 2 years in patients with BPH resulted in median reductions in serum DHT of 93%.4 In contrast, therapy with finasteride (5 mg daily) suppressed serum DHT concentrations by approximately 70% for up to 4 years in patients with BPH.5 These observations raise the question whether the pharmacologic differences in DHT suppression between a selective versus a dual inhibitor of 5AR results in clinically significant differences in the treatment of BPH.
Btw, rashes are reported in 5 AR therapy, the reason wasn't clear though.
This is significant because dihydrotestosterone is thought to be important in the development of BPH; its suppression by these 2 agents may prove to be beneficial for patients with BPH.
Comparison of Clinical Trials With Finasteride and Dutasteride
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472914/pdf/RIU006009_0S31.pdf
Results of a phase II, double-blind, placebo-controlled, comparative dose-ranging trial of dutasteride and finasteride clearly demonstrated that serum DHT suppression was significantly greater with dutasteride (0.5 mg daily) than with finasteride (5 mg daily).3 The mean reduction in base-line DHT concentration in patients receiving 0.5 mg dutasteride daily was 94.7 ± 3.3% and for patients receiving finasteride 5 mg daily was 70.8 ± 18.3%, respectively (P < .001) (Figure 2). In non-comparative clinical trials, chronic therapy with dutasteride (0.5 mg daily) for up to 2 years in patients with BPH resulted in median reductions in serum DHT of 93%.4 In contrast, therapy with finasteride (5 mg daily) suppressed serum DHT concentrations by approximately 70% for up to 4 years in patients with BPH.5 These observations raise the question whether the pharmacologic differences in DHT suppression between a selective versus a dual inhibitor of 5AR results in clinically significant differences in the treatment of BPH.
Btw, rashes are reported in 5 AR therapy, the reason wasn't clear though.
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