The worst thing to do would be to throw in the towel on these medications. You don't build a tolerance, it's just that the older you get, the less drugs can protect you from balding (DHT is a cruel thing). Genes are powerful, and sooner or later they are going to win the war (most likely). The fact you made it to your forties alone is commendable, I started seeing deterioration at 20, and it was heartbreaking! Of course, no man wants to lose his hair, so you do have one or two options left, but you need to think about your commitment to keeping hair.
Clearly, your hair loss is stubborn and if you are significantly receded you may wish to consider transplant surgery... if your bank account permits of course!
Alternatively, you can look into Dutasteride (Avodart). It isn't FDA approved in the UK/US, so exercise some caution, but in certain countries many men are taking it problem free. If you've had no side effects from proscar, it's definitely worth considering this medication. It blocks a greater DHT percentage and also works in one other area that Finasteride (proscar) does not, but the exact details of that escape me. Of course, procuring this is more challenging, but many men have done so and found that it has halted or slowed hair loss right down where all other medications could not.
What's more, it's another step up, and you should educate yourself on it further, but I absolutely believe if you get on it, you will most likely see that hair loss stop/slow to a crawl, at least for another few years. You might want to consider the other form of Rogaine (I believe it is liquid, and can be applied using a pipette). There's a risk of slight scalp irritation, but some have argued that it takes a tougher line with the hair and encourages greater growth. -You might also invest in the laser comb? I was chatting with my friend who's a specialist at the Belgravia Centre, and she was talking about just how helpful that device has been for so many of her patients in slowing hair loss down. It's worth at least considering if you want to really max out your options.
In terms of your lifestyle/drugs specifically... A mild dose of testosterone= greater levels of DHT (as that's what testosterone is assimilated into, and it then binds to and weakens follicles). I would posit that this has some impact, but only very mild, and if it is health related, do not bring yourself off it for the sake of hair, not when there are other options available to you!
I hope this helped a little bit. There's still plenty of options available to you, so have a look around the ones I mentioned specifically, and hopefully you'll slow that loss right down, and buy yourself 5 years or so.
Take care,
Chris.
