Background
Androgenetic alopecia (AGA), also known as male pattern hair loss (MPHL), is
the most common form of hair loss, affecting approximately 50% of Caucasians
over the age of 40 years (1). In males, AGA can begin as early as late
adosescence; however, the usual onset is at around the age of 30 years (1). AGA
results from naturally circulating androgens which progressively transform large
terminal scalp follicles to smaller vellus ones, thus resulting in a visibly
less dense scalp (2).
Testosterone is the major circulating androgen in the body, but must be
converted to dihydrotestosterone (DHT) via the enzyme 5 a -reductase in order to
be active in the skin (3). Studies have shown that men with 5 a -reductase
deficiency do not develop AGA (*3,4). Therefore, 5 a -reductase inhibitors have
been evaluated for the treatment of AGA due to their ability to inhibit the
conversion of testosterone to dihydrotestosterone (3,5). Two isoforms of 5 a
-reductase are known, type 1 and type 2. Type 2 is predominately located in
human genital tissue. Type 1 is distributed throughout the body, and
predominates in the skin and scalp (3).
Avodart is a competitive inhibitor of 5 a -reductase, the enzyme
responsible for the conversion of testosterone eo dihydrotestosterone (DHT) in
the prostate. It inhibits both enzyme types 1 and 2 and is incdicated for the
treatment of symptomatic BPH in men with an enlarged prostate to improve
symptoms, reduce the risk of acute urinary retention, and reduce the risk of the
need for BPH-related sur4gery. Avodart is contraindicated for use in women and
children and for patients with known hypersensitivity to dutatsteride, other 5 a
-reductase inhibitors, or any component of the preparation (6).
One clinical trial evaluating the use of Avodart in AGA has been
conducted and is discussed below. No large, prospective clinical trials have
evaluated the use of Avodart for this use.
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