The original question was how "natural" MMJ products establish dosage and ensure purity & potency. Were I an consumer/end user (which I might be were it legal here), these questions might be important to me, as they are with supplements now. But we're not talking about supplements here; we're talking about medicine—which is (otherwise) held to much higher standards and regulation—which would (and should) make these questions even more important to me. I really don't want to be ingesting things that aren't what they claim to be, or may contain toxic contaminents. (If it's in the plant material, chances are it's in the oil extracted from the plant material.) There are certain brands/kinds of supplements I won't touch for some of these same reasons; why would I give MMJ products a pass?

Straw man responses aside, I don't think we're on the same page. I've been bringing up observations & questions I see as obstacles to MMJ being both legalized and accepted as medicine, including acceptance and coverage by medical insurance.

The cost of Sativex (or Marinol) today is a valid point, but all medications are expensive during patent. That patent has a limited life, after which it will be available generically, at greatly reduced cost. Cost may drop sooner if/when the political situation changes and competition enters the market. I'm not really worried about purity, potency, or dosage in regulated medicines.

I see enormous potential in the medical uses of compounds found in cannabis, but (as previously stated) we've lost ~80 years of valuable research time. Most research done thus far has been with the two most common of these compounds—THC & CBD—yet there are at least 83 more that may have significant roles to play that we know little or nothing about yet; some may have or enhance therapeutic value (e.g. CBC), and some may hamper or counter it—we don't know yet—we have a lot of catching up to do.

Medical and recreational proponents alike claim that combinations of both CBD & THC are/work better than either compound individually. Sativex contains both at an ~1:1 ratio.
To those who would cultivate their own, the same article explains why it's not as simple as obtaining and growing seeds from some particular strain. There is also some question (sources differ) about practical limits (# of generations, potency) of "cloning".

I can see a day when we will go to our doctor for some complaint, and s/he'll be able to write us a prescription for a cannabinoid medication specifically formulated for what ails us, without (as significant) risk of adverse effect. I have the same vision for rainforest plants—if we're not so foolish as to lose them all to deforestation first.

In the meantime, while MMJ has therapeutic value and advantages over many Big Pharma alternatives, it still has the same trial & error methodology to find what works, and is not without downside. It's kind of like using opium poppies or raw opium, or ingesting mold (for antibiotics). Sometimes a little refinement can be a good thing.

I couldn't agree more that we all have to make our own best decisions and take responsibility for our own care, but I believe that the best decisions are made by discussing/examining/presenting the broader picture and asking/raising the tough questions.

You have my interest, support, and gratitude, and I'm thrilled that it's giving you your life back. I envy you that I cannot try it myself, but if/when I can, I think I will still approach it with caveat emptor in mind.

Doc