Finasteride 1.25mg, 100 capsules per bottle

Finasteride was available for years as Proscar (5mg tabs), but only recently became available as Propecia (1mg tabs). It is in a class of chemicals known as 5alpha-reductase inhibitors. It is based on the progesterone skeleton (4) and has a high inhibitory activity for the enzyme 5alpha-reductase (5-AR). 5-AR, as you may recall, is the enzyme responsible for converting certain steroids into 5-Alpha Reduced versions of themselves (such as turning testosterone into dihydrotestosterone). Finasteride and similar compounds are used for the treatment of androgen dependent diseases such androgenic alopecia (hair loss), benign prostatic hyperplasia (prostate enlargement) and prostate cancer. Dihydrotestosterone is a 5alpha-reduced metabolite of testosterone and has been implicated as a causative factor for the onset and progression of these problems. This was discovered when males who are genetically deficient of the enzyme steroid 5alpha-reductase were shown to have much lower incidences of these problems (1)(2). Of course, these problems can be a major annoyance, and nothing to toy around with, but by using finasteride you risk reducing your gains on a given cycle, and can even suppress reproductive function (3). I’m not a big fan of this, as you could guess. However, if you are worried about your hairline, or have incidences of prostate issues in your family, then 1mg/day of Finasteride may be the answer you’ve been looking for.

It needs to be noted that there are actually 2 different 5-AR enzymes, and Finasteride specifically blocks the type-II variety. The type-II 5-AR enzyme is the one responsible primarily for hairloss and prostate enlargement, while type-I is often the culprit behind acne and hirsutism. In either case, type-II is responsible for around 2/3rds of the circulating DHT in your body, so it’s no surprise that Finasteride typically reduces your total DHT levels by around 65%.

1. Steroidal antiandrogens and 5alpha-reductase inhibitors. Curr Med Chem. 2005;12(8):927-43.
2. New 5alpha-reductase inhibitors: in vitro and in vivo effects. Steroids. 2005 Mar;70(3):217-24.
3. [Effect of selective 5alpha-reductase inhibitor or/and testosterone undecanoate on the reproductive function of male rats] Zhonghua Nan Ke Xue. 2005 Jan;11(1):38-41. Chinese.
4. New aromatic esters of progesterone as antiandrogens. J Enzyme Inhib Med Chem. 2004 Apr;19(2):99-105.
5. Biology of Reproduction 50, 1244-50 (1994)


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