What are 5α-Reductase Inhibitors?
5α-Reductase Inhibitors are a class of drug that blocks the 5α-Reductase enzyme in the body. Well, what does the 5α-Reductase enzyme do? The 5α-Reductase enzyme, is the enzyme by which Testosterone gets converted into DHT (Dihydrotestosterone), which is the hormone we want to eviscerate in out bodies.
What 5α-Reductase Inhibitors exist and their differences?
There are two 5α-Reductase Inhibitors we can chose from.
- Finasteride
- Dutasteride
When concerning ourselves with DHT (Dihydrotestosterone), we have to realise that there are two isoenzymes. There is the type 1 isoenzyme, and the type 2 isoenzyme. Finasteride (branded name being Propecia) is the most commonly used 5α-Reductase Inhibitors and is what is typically prescribed for hair loss. Finasteride will only inhibit the type 2 isoenzyme, however Dutasteride (branded name being Avodart) will block both the type 1 and type 2 isoenzymes of DHT.
What effects does 5α-Reductase Inhibition have on development?
This question can be answered through the research conducted on twins, two of which are deficient in the 5α-Reductase enzyme, and the other having normal 5α-Reductase enzyme. This allows us to compare their development to each other, and actually deduce what effects the inhibition of the 5α-Reductase enzyme, or lack of DHT will have on development.
Effects on bone development/growth
Here we can see 3 individuals. The two on the left are deficient in the 5α-Reductase enzyme, where as the one on the right has normal 5α-Reductase enzyme activity. Despite the fact that they are deficient in 5α-Reductase enzyme (meaning they have extraordinarily low, practically 0 DHT in their bodies) they still have a normal bone structure and an identical height, bone density and skeletal mass to their healthy siblings. From this we can easily conclude that DHT does not have any effect on bone growth and development.
Effects on dick growth
This is the reason that we should keep DHT circulating our bodies until we are about 16 years old. In the twin studies, the twins who are deficient in the 5α-Reductase enzyme developed a micropenis, which is obviously not idea. So, clearly, DHT is essential for the development of the male genital. However, as I mentioned, earlier, this is largely completed by the age of 16, during puberty. So after this point is does not provide any befits, and only detriments to our looks.
Why we want to use Dutasteride over Finasteride (skin)
As I previously mentioned, Dutasteride is going to block the type 1 and type 2 isoenzymes, where as Finasteride only inhibits the type 2 enzyme. Both are going to help reduce your hair loss or halt it, however the real reason we also wasn't to inhibit the Type 1 enzyme is for the skin benefits. Androgens will cause an upregulation of the sebaceous glands, which cause more oil and sebum production. This result is more acne. It also causes loss of elastin over time, which is impossible to get back, so prevention is the best thing to do, and that requires Dutasteride.
Will 5α-Reductase Inhibition and a lack of DHT detriment muscle building?
DHT has absolutely zero effect on muscle building and is not anabolic in the slightest. DHT is metabolised by 3-alpha-hydroxysteroid reductase in muscle tissue which converts into 3α-androstanediol which has close to no androgen receptor affinity. This rapid inactivation significantly diminishes its anabolic effects in skeletal muscle which means it is not anabolic in the slightest.
https://pubmed.ncbi.nlm.nih.gov/22396515/
Dosage protocols
When dealing with Dutasteride, the typical dosage is 0.5mg per day. However, for maximal DHT suppression we will be wanting to take 2.5mg every day. This will give maximal DHT suppression allowing the preservation of your hair and skin.
If you are opting for Finasteride, 1mg is enough for hair loss. 5mg is prescribed for enlarged prostate, but does not serve any benefit for hair loss. 1mg and 5mg are as effective as each other for hair loss.
Side effect profile
Many are concerned about the sexual side effects of 5α-Reductase enzyme inhibitors. There are going to be the very unfortunate minority that may get side effects, however they are very very over blown through places like Reddit and social media.
Even in long-term studies (10 yr +) in Asians, no evidence of PFS symptoms were ever discovered. Only 1-3% get sexual sides, which wasn't even significantly different from the placebo arm in the original trials.
Only after social media started popping off did the side effect reports started skyrocketing. And no, it’s not because there were fewer users back in the 2000s, millions of men were already on it back then.