Whenever we consume a new cannabis edible or tincture, the only thing we know for sure is that we don’t know what to expect. Is this going to put me to sleep for the day or will I want to smoke some flower to get the ball rolling?
Unfortunately, the level of precision in dosing remains elusive for most cannabis treatments, especially those made by patients in their home. Those familiar with cannabis and one of its most wonderful attributes, that there is no lethal dose, understand that over-consuming doesn’t carry the dangers present with other pharmaceuticals but can still cause some undesirable side effects. As such, clarity and consistency in dosing is critical to allowing patients to have reproducible (and therefore legitimized) treatment, especially where the patient is seeking cannabinoids solely for a medical purpose or the goal is to medicate as little as possible to be effective, as in the case of children.
MCR Labs’ quest to arm patients with the data they can use to achieve greater accuracy began with the development of a dose calculator (available on each publicly shared product page in our “Products We’ve Tested” section) that can be used to quantify the amount of cannabinoids present in a given cannabis product; the first step towards accurate administration. Our experiments to hone in on the rate of THC consumption during vaporization gave further ammunition to patients who want to know the science behind various delivery methods.
Aside from inhalation methods including vaporizing and smoking, patients are increasingly incorporating cannabis into their health regime using edible extracts. Whether a butter, oil, tincture, or salve, these medicines are created by transferring the cannabinoids from the plant into a secondary medium which can then be incorporated into food, smoked, or used topically or sublingually.
While extractions are popular with patients and have myriad uses, they are subject to the problem of accurately quantifying the amount of medicine in each dose. Even where the patient knows the cannabinoid profile within the starting plant material, once the solvent is introduced, it often becomes a guessing game when attempting to dose with the results. While lab testing is one concrete way to uncover the answers, patients can guide their medicine production and understand the science behind extract dosing by considering and incorporating these formulas MCR has prepared.
A general outline in preparation of tinctures is:
- Weigh out known amount of cannabis flower (m grams)
- Decarboxylate as desired
- Add (c) fluid ounces of a solvent – grain alcohol or vegetable oils are best
- Let sit for an hour, stir occasionally. Heat generally increases solubility.
To generally understand how cannabinoids absorb into a solvent, consider the following, which assumes a starting flower of 15% potential THC, and full extraction into the solvent:
- m = The amount of starting plant material in grams of bud
- c = fluid ounces of solvent (the olive oil, glycerin, grain alcohol, or other fat/alcohol used as the extraction medium)
- r = milliliters of the final product the patient plans to use as a dose
- L = mg of THC
when using the following formula: 2.5*(m/c)*r = L
If MMJ patient Susie were to use 5 grams of plant with 2 ounces of liquid, and plans to take 5ml (1 teaspoon) of medicine as each dose, she would expect to get 31 mg of THC with a full extraction:
2.5*(5/2) * 5 = 31
Susie could also use this version of the formula if she was looking for a specific dose. If Susie wanted a 20 mg dose, she can use this formula to inform her of the amount to take:
R = (0.4*L*c)/m
In Susie’s case, R = (0.4*20*2)/5 = 3.2 mL
So using the same amount of plant and solvent but seeking a 20 mg dose she would take 3.2 ml of the formula.
These simple calculations are aimed to provide guidance to the cannabis home chemists, and food for thought to those just beginning to encounter extracts. Be sure to read through the advanced notes directly below for some deeper issues to consider when thinking about accurate cannabis dosing:
1) The formula assumes a 15% potential THC as a middle ground number, but obviously the potency of bud varies widely from 5% to over 25%. If the patient knows the potency of your bud is p, the formula may be amended to include p for increased accuracy:
17*p*(m/c)*r = L
2) The formula assumes 100% extraction efficiency of the cannabinoids into the solvent. The actual extraction efficiency will depend on the solubility of the cannabinoid into the extraction medium and the extraction process. One bedrock principle to remember for eternity is that cannabinoids are not water-soluble. Even 40% ethanol (vodka) will contain enough water to impact extraction efficiency. The best way to find your extraction efficiency is to test your tincture and raffinate (left-over bud after straining), or in the absence of the ability to test, choosing a solvent with a very high fat or alcohol content (no, glycerin is not a good solvent for cannabinoids).
Big thanks to Shanel Lindsay, of Ardent, for coauthoring this post!