In a *study presented by the Journal of American Academy of Dermatology 2006, 416 men with male pattern hair loss (MPHL) ages 21 to 45 years old, were randomized to receive dutasteride (Avodart) 0.05, 0.1, 0.5 or 2.5 mg, finasteride 5 mg, or placebo daily for 24 weeks. The results of the study showed that dutasteride (Avodart) increased hair counts in a dose-dependent fashion and dutasteride 2.5 mg was superior to finasteride 5mg at 12 and 24 weeks.
While it is true that testosterone is the major circulating androgen (killer of hair follicles), to be maximally active in the scalp hair follicles it must first be converted to dihydrotestosterone (DHT) by the enzyme 5a-reductase. There are two types of the enzyme 5a-reductase. Type 2 has been shown to be the principal factor in hair loss of men with Male Pattern Hair Loss (MPHL). Avodart ( dutasteride ) inhibits both type 1 and type 2 5α-reductase and is approved at the 0.5-mg dose for treatment of symptomatic benign prostatic hyperplasia (BPH). It is about 3 times as potent as Propecia ( finasteride ) at inhibiting type 2 5α-reductase and more than 100 times as potent at inhibiting the type 1 5α-reductase enzyme.
Avodart ( dutasteride) effects on Scalp and Serum DHT
Scalp DHT refers to the concentration of DHT found in the scalp, while serum DHT refers to the DHT present circulating through the blood. Avodart dutasteride caused scalp and serum DHT levels to lower and testosterone levels to increase in a dose-dependent fashion. Whereas 5-mg Proscar finasteride decreases serum DHT by about 70%, Avodart dutasteride can decrease serum DHT by more than 90%.
Avodart and Propecia study results
In this phase II, dose-ranging study, 2.5-mg dutasteride was superior to 5-mg finasteride in improving scalp hair growth in men between ages 21 and 45 years with MPHL as judged by target area hair counts, expert panel assessment, and investigator assessment at 12 and 24 weeks.
In a test area at 24 weeks, results showed:
Placebo −32.3 hairs
Finasteride 5mg 75.6 hairs
Dutasteride 0.1 mg 78.5 hairs
Dutasteride 0.5 mg 94.6 hairs
Dutasteride 2.5 mg 109.6 hairs
Avodart and Propecia Sexual Side Effects
As far as possible sexual adverse events, there was no evidence in the present study that either Avodart dutasteride or Propecia finasteride was associated with impotence. However, 9 men in the 2.5-mg Avodart dutasteride group complained of decreased libido, compared with 1 man in the 0.5-mg Avodart dutasteride group and 3 men in the Proepcia finasteride group. As with previous studies with finasteride, this adverse event was characterized as either mild or moderate in severity and often resolved with continuation of the medication. In the 4-year follow-up of the phase III trials in BPH, dutasteride (0.5 mg) was well tolerated and the occurence of the most common sexual adverse events was low and tended to decrease over time.
Will Glaxo develop Avodart or Dutasteride for approval to treat hair loss?
It is unlikely that Glaxo Smith Kline will see enough of a profit margin in Avodart by investing in a controlled trial to get FDA approval for treating male pattern baldness. Right now it’s a matter of economics. However, some doctors will issue a prescription for the “off-label” approved use of Avodart for hair loss as long the patient is well informed about the medication and side effects
*Journal of the American Academy of Dermatology 2006; 55(6): 1014-1023 |
