Alright, so I decided to take the plunge and try it for myself. I'd call it a success, but with a few caveats.
Bloodtests:
I had my serum dht tested prior to applying, and six and a half days post-application. I tried to keep the variables as consistent as possible: time of testing (both at 9AM), amount of sleep prior, etc. I chose to measure the value at around seven days because I would ideally use it once weekly, so this would roughly tell me whether a re-dose at that point was feasible. I would have liked to get more bloodtests at different intervals but they're expensive and a huge hassle to get done.
Application:
I only had a 1% bottle (liposomal) from Farmacia Parati available. I wanted to use around 2.5mg, so I measured out a little over 0.25ml (to compensate for whatever got stuck in my hair) and asked my girlfriend - god bless her - to meticulously apply it to my crown. She was actually able to get quite a bit of coverage, but if I had to do it myself it would probably be difficult (albeit not impossible).
In dgadgdea's case, 0.1% appeared to cause no reduction in serum dht. I wanted to avoid dosing too high (I would really rather not use these drugs at all, and given dutasteride's dose-dependent halflife I knew I had to be careful), but not too low either because that wouldn't give me a lot of new information. So I settled on 2.5mg.
Results:
My serum-dht at baseline was 0.68 nmol/l, and 6.5 days after applying 2.5mg of dutasteride it was 0.64 nmol/l. So a difference of roughly 6%.
Sidenotes:
1. By doing this experiment, I accidentally found out my dht levels are quite low in relation to my testosterone levels. The ratio seems to be way off. I wasn't coming off finasteride/dutasteride, and I wasn't born with 5ar-deficiency either. I'm looking into it and it's more of a personal issue, but I felt I should mention it to you guys for the sake of transparency. The first (baseline) bloodtest only tested dht. Only in the second one did I include testosterone, because I was surprised by the low inititial dht-reading. It's theoretically possible that, for some reason, my testosterone levels (and thus dht) were really low at baseline, but normal at the follow-up test. That could mean that dutasteride was supressing dht at follow-up, and the fact that the two values are almost identical was merely a coincidence. I don't think it's likely though, because that would be a pretty big coincidence, and it would have to be a huge fluctuation in testosterone, even though I kept every variable as consistent as possible. I'll be getting more tests, this time from a different laboratory to shed further light on this.
2. It seems like it reduced my shedding. Could be a fluke, and I also don't know how I would even explain it given what we know about hair growth/loss. These drugs shouldn't be able to work that fast.
3. I may have experienced some mild side effects. I think I noticed a slight reduction in libido for around 3 days after applying it, after which it quickly improved back to normal. This may have all been in my head though. I really don't underestimate the power of placebo when it comes to things like libido. Whatever the case may be, I felt completely normal at the 5 day mark.
4. Applying 0.25ml of 1% concentration may be different from applying 1ml of 0.25%.
Analysis:
My results appear consistent with what Mustang, Vincent and Dgadgea reported, although I do not think I'd personally be able to tolerate extremely high doses with almost no effect on serum dht, like Mustang and Vincent report. Still, I'm cautiously optimistic. I'm aware that a single experiment like this, with only testing serum dht, has its limitatons. I'll obviously need more data in the future, which I intend on getting.
So, although it's hard to draw definitive conclusions from this, I'm inclined to believe that a 0.25% dose, for me personally, is feasible in the sense that 5-alpha-reductase (in the rest of the body) is either fully or mostly recovered at the 7 day mark. So re-dosing at that point would be possible without significant accumulation. I can't be sure whether I actually experienced side-effects, especially because they felt quite mild. However, if I had to draw a conclusion one way or the other, I would say that I did actually experience them and it wasn't due to nocebo.
Going forward, I'll be assuming that this was indeed the case and that my dht-levels were somewhat inhibited following application, and then quickly returned to baseline. If I'm correct, that tells me the 0.25% dose was too high for what I'm trying to do, but not that far off. Alternatively, I'm wrong and it was all nocebo and my dht levels weren't impacted at all. But I'd rather err on the side of caution in this case and leave myself room to gradually increase the dose. It'a shame I couldn't get another bloodtest at the 3 day mark or something, but as I said, they're expensive and a huge hassle to get done.
For my next experiment, I'll adjust the dose to 0.1% (1mg). Given my experience with 0.25%, this should be sufficiently low to avoid any significant impact on serum dht. I should have an actual 0.1% bottle available by then, so that I can apply the entire 1ml.
At this point, I'm more concerned with questions of effectiveness rather than safety. We still don't know whether applying once a week is enough/optimal. I would like to eventually figure out if I can lower the frequency further to every 4 or 5 days. That's why I'm planning to do the following. I'll apply 1ml @ 0.1% once weekly, for four weeks in total, and evaluate with a bloodtest. If the results are as expected, I will start re-dosing after 6 days rather than 7, evaluate with another bloodtest after 4 applications, and keep repeating the process.