Thanks lol. The name just popped into my head for some reason. There's definitely a lot of people on these forums that are way smarter than I am, you are for sure, especially with hormonal expertise.
Half lives, in a practical sense, refer to how long the drug is in the system. For example, oral minoxidil has a half life of approximately 4 hours. This means that if you took, say, 10mg at 8AM, approximately half of that (5mg) would be in your system at 12PM. Then 2.5mg still at 4PM. I've read that usually 5-7 half lives is the point where it clears. So 4 hours X 5 half lives = about 20 hours in your system. So if you are taking a drug with a substantially longer half life, like dutasteride, which has a phenomenal half life of 4-5 weeks, you really don't need to take it very frequently - caveat - it should be noted that the drug first needs to reach a steady-state before it lasts that long in the system. This is why many will start a "loading phase" of duta of around 2.5mg daily for a week or two, then take it only a couple times a week. But, theoretically, once you are loaded into that steady state, you could take it once every week or longer and maintain the same serum concentration. A while back I read somewhere in the forums about dutasteride being used topically say once a week or once a month and there was some study showing it being nearly as effective as if applied more frequently. Also, most compounds will have a substantially longer half when applied topically. For example, topical minoxidil has a half life of 22 hours, hence why good results can be realized by using it once daily. It still will likely be more effective twice daily though, as the concentration will be doubled (5% twice a day is the same amount as 10% once a day) and the drug will remain more steady in the system the more frequently it is applied. All this being said, just because a drug is no longer in the bloodstream, that doesn't mean that the effects of it do not last longer (finasteride being a prime example with a half life of only 5-6 hours, but once it reaches a steady state, it takes a few weeks for DHT to return to normal).
Molecular weight helps us to understand how well the given substance absorbs. Generally, the smaller it is the more systemic it will go. Minoxidil is around 200g/mol, possessing one of the lowest molecular weights of all of the hair loss topicals, thus it absorbs well into the scalp compared to something like dutasteride which has a molecular weight of over 500g/mol. So although duta has a long half life, the molecular weight is going to make it less potent (but also less systemic which is advantageous for those seeking to avoid that).
As Murkey pointed out, finding the right balance is complex.
Dermarolling/needling etc is also going to affect the penetration and how systemic these things go. There's different philosophies on this too, the method of needling, as well as the frequency/intensity. Most do a weekly wound, but then there's people like Somebody Alex who got amazing results from just a very light daily roll without any bleeding at all. So customizing/optimizing these methods will depend on what substances you're using.
It's impossible to find a perfect formula, but my philosophy is to try to find at least some pieces in the equation that fit most closely to one's specific goals and their unique individual characteristics. A lot of it is simply going to be experimentation, trial and error, and theorizing. There is no way around it when the only thing that matters is the outcomes. There is so much statistical data out there - which is important, and it's interesting to delve into the complexities of such - but at the end of the day it can be overwhelming, distracting, and even downright depressing to not have a simple cure in the palm of our hands like we do for a number of deadly diseases. We simply have to give some things our best guess and just test it out. Anyways, I'm rambling now so I digress.
Good info, thanks!