FINASTERIDE EFFICACY – WHY PROPECIA DOESN’T ALWAYS WORK?
Propecia does not always work for everyone with androgenetic alopecia. There may be several reasons for this.
Propecia is a type II 5 alpha reductase inhibitor. That means it blocks about 70% of the 5 alpha reductase activity in the body. Propecia has no effect on type I 5 alpha reductase, which accounts for about 30% of reductase enzyme activity in the body. So even when using Propecia there is always some conversion of dihydrotestosterone or DHT from testosterone. This limited DHT supply may be enough to maintain androgenetic alopecia in some people.
The efficacy of finasteride in this case is not guaranteed.
Efficacy of finasteride – Better if androgenetic alopecia has just started
It is well known that drugs such as Propecia are less effective in people who have had pattern baldness for many years. This is due to hair follicle destruction. In the early stage of pattern baldness hair follicles become miniaturized but still produce small vellus hairs. These hair follicles could still potentially be reactivated to produce full terminal hair again. However, after several years of miniaturization, hair follicles become so weak that they stop growing altogether. These follicles are entirely destroyed. Once destruction occurs it is impossible to stimulate these follicles back into growth no matter how powerful the drug.
There are probably different types of pattern baldness where one contributing factor important in promoting hair loss in one person is different from the factor promoting hair loss in another person. For example, DHT may be a big promoter of hair loss, but for another person it may have a lesser role. Or perhaps the activity of type I 5 alpha reductase is greater than type II activity in one person but the complete opposite could happen to another person.
Efficacy of finasteride and androgenous receptors
Or one person has more androgen receptors on the cells of his hair follicles then small amounts of androgen hormone have a bigger adverse impact. The extent of hair loss may be the same in two individuals but the importance of different androgens and androgen receptors in the development of hair loss may differ from person to person.
All these subtle differences may mean that a treatment that works well by acting to block dihydrotestoerone production through 5 alpha reductase inhibition may work well for one person but will work less well for another where hair follicles have high numbers of androgen receptors that can be triggered.