Reduce The Effectiveness / Side Effects Of Finasteride With St. John's Wort?

[stupidkoko]

So this is a topic I surprisingly haven't seen being discussed on this forum and I though it might be interesting to some.
I'm not sure if I should have posted this in the research section of the forum or here, but I hope it reaches the attention of those who are interested.

Study Summary: https://www.ncbi.nlm.nih.gov/pubmed/19073252
Full Study: http://www.diva-portal.org/smash/get/diva2:343053/FULLTEXT01.pdf

Basically from my understanding of this study, there's a drug interaction caused when finasteride and St. johns wort are taken simultaneously. Finasteride gets metabolized through the enzyme of CYP3A4 found mainly in the liver and with St. johns wort treatment the production of this enzyme is increased.
With induced metabolism of finasteride this leads to less plasma exposure of the drug, meaning finasterides effectivity is reduced from taking St. johns wort.
In a separate part of the study they also tested the effect from inhibition of CYP3A4 with ketoconazole (in pig) and found it would lead to increased finasteride plasma exposure and therefore increased side effects.

Of course this also means that one is getting effects from the St. johns wort treatment which may or may not be desired for the time it's used simultaneously.
The herb is otherwise mainly used to treat mild to moderate depression, anxiety and insomnia.

A high enough concentration of pharmaceutical drugs are necessary to achieve the desired effect, but a too high concentration may also cause undesired side effects. Could this be a way to minimize the risks of gettings side effects from finasteride? Or could this be an effective way to slowly wean on/off finasteride?

I'm no doctor and this is not intended to be medical advice, please don't quote me on anything because this has only been my understanding of the study.
I've experienced side effects myself when taking finasteride years ago. I've not tried taking it in conjunction with St. johns wort.

 

[hopeforhappiness]

Does st. johns wort have a similar effect on other drugs ? Also could this mean that finasteride could be administered topically while ingesting st j wort to avoid systemic dht reduction ? Or would finasteride in the blood via scalp have no interaction with st j wort in the stomach ? Also wouldn't reducing the effectiveness of the drug be equal or less affective than just taking a smaller dose ? Or would this inhibit the build up of finasteride in the system ?

 

[stupidkoko]

Does st. johns wort have a similar effect on other drugs ? Also could this mean that finasteride could be administered topically while ingesting st j wort to avoid systemic dht reduction ? Or would finasteride in the blood via scalp have no interaction with st j wort in the stomach ? Also wouldn't reducing the effectiveness of the drug be equal or less affective than just taking a smaller dose ? Or would this inhibit the build up of finasteride in the system ?

Any other pharmaceuticals that are metabolized through CYP3A4 would probably be affected.
As for reducing the effectiveness by taking a smaller dose, yes of course but if you've seen any of the graphs made on finasteride plasma DHT reduction you know that the drug has a very flat response. Taking even 0.05 mg finasteride have nearly the same effect as 1 mg, but the only way to get equally smaller doses is to dissolve it in alcohol and even then you have to consider the half life of the drug etc.
I can't answer for your other questions. I don't know more than what the study explored within the field.

 

[mojojuju224]

This is a pretty tedious read because of all of the scientific discussion of metabolites, but regardless of whether St. John's Wort affects the metabolism of finasteride, you're still dealing with the inhibition of the 5AR enzyme. Finasteride is usually out of your system fairly quickly anyway; the enzyme inhibition is more important. I would guess that, initially, it might take longer to reach a steady state with finasteride using St. John's Wort, but after some time, the 5AR inhibition would essentially catch up and the results would be nearly the same.

 

[stupidkoko]

This is a pretty tedious read because of all of the scientific discussion of metabolites, but regardless of whether St. John's Wort affects the metabolism of finasteride, you're still dealing with the inhibition of the 5AR enzyme. Finasteride is usually out of your system fairly quickly anyway; the enzyme inhibition is more important. I would guess that, initially, it might take longer to reach a steady state with finasteride using St. John's Wort, but after some time, the 5AR inhibition would essentially catch up and the results would be nearly the same.

I've seen numerous reports of other medications interfering with this herb and they've all made the medication less effective, sometimes close to almost completly ineffective. When simultaneous medication with st. johns wort ceased the blood test measures reached expected levels. When restarted, the measures started to change again.
I understand it may be boring to those who have no problems taking the drug, but for the ones that can't tolerate it finasteride is today the base treatment against hair loss.

 

[mojojuju224]

I've seen numerous reports of other medications interfering with this herb and they've all made the medication less effective, sometimes close to almost completly ineffective. When simultaneous medication with st. johns wort ceased the blood test measures reached expected levels. When restarted, the measures started to change again.
I understand it may be boring to those who have no problems taking the drug, but for the ones that can't tolerate it finasteride is today the base treatment against hair loss.

This is all just speculation. Just because St. Johns Wort affects the metabolism of other medications doesn't mean it will, in the end, lead to much less inhibition from finasteride if it reaches a steady state, though it has been shown to decrease the effectiveness of finasteride by affecting enzyme CYP3A4 metabolism. We just simply don't have the information on what that means for efficacy over the long term because finasteride is an irreversible inhibitor of 5AR. On another note, what is the point of trying to take a medication to cancel out another medication's effects? You would just end up with wildly different plasma concentrations of the drug that you can't measure and would be limiting finasteride's ability to actually stop hair loss and regrow hair. In general it's not a good idea to take one drug to mitigate the effects of another drug. If you have side effects from finasteride, stop taking the medication. Also, I didn't say it was boring; I meant it was difficult to read for the layman because of how it's written.

 

[Thor9]

Bump - seems like a good option for people taking small doses of topical finasteride.