Medical Cannabis Ratios and Concentrations

Why are both ratios and concentrations important?

Cannabis ratios are widely used, but are less broadly understood. Manufacturers use several different ways of naming their products, and for communicating its content. Some use a percentage for the concentration. For example, 5% CBD actually doesn’t mean 5mg/ml, but 50mg/ml. This is because you have to work backwards from a gram, which is 1,000mg, hence 5% is 50mg.

If that isn’t confusing, the fact that some 1:20 oils are actually 5:100 in terms of mg/ml content or could even be 3:60. Cannabis ratios don’t necessarily refer to the actual content, which just illustrates how important it is to look at both ratios and concentrations. In this article we will explain the different terms you may be familiar with in cannabis medicines, what they mean and how they translate to what’s in the bottle.

The importance of Medical Cannabis Ratios

To recap, phytocannabinoids are the chemicals and compounds that naturally occur in cannabis. More than 60 have been identified and studied with regards to their effects on the human body.[1] The most abundant of the non-psychotropic is cannabidiol (CBD). Tetrahydrocannabinol (THC) is the main psychoactive cannabinoid which can cause the sensation of feeling “high” at certain doses.

Other constituents of medicinal cannabis products are generally less abundant and include other cannabinoids such as CBG or THCV, terpenes and flavonoids and anti-oxidants. The minority content of these components can’t be totally disregarded and the claimed ‘entourage effect’ highlights the synergistic relationship many of these minor components may have on CBD and THC, as well as on their own.[2]

With an increasing range of both CBD and THC-containing products available, it can be important to remember that not all products are created equally. The proliferation of over-the-counter CBD oils and related products are technically being sold as food supplements.[3] The Novel Food Authorisation testing means they must be safe for consumption, and little else.

This does not apply for prescribed cannabis medicines where quality requirements are much clearer and well defined and also dictate purity. If we focus on CBD and THC for a minute, within the UK medicinal cannabis space there are several terms that are used in relation to cannabis ratios and medicine formulation.

Ratios in Cannabis Medicines

In many cannabis medicines a ratio is regularly used such as 20:1 or 10:10 to describe the formulation of the product, but in terms of what’s in the bottle, what does the cannabis ratio mean?

The cannabis ratio is set out to reflect the different relative concentrations of cannabinoids present. Conventionally listed as THC first, the higher the number the greater the concentration of that cannabinoid per weight is present relative to the other.

To put this in the perspective of this article, it is important to stress that the cannabis ratio reflects the quantity of one cannabinoid in relation to the other, and does not always reflect the absolute cannabinoid content of a medicine. This should always be considered when the patient and doctor are discussing which medicine is to be prescribed, or when buying an over the counter (OTC) product.

As ratios do not always reflect the cannabinoid content it can be easy to mistake a higher ratio for having a higher cannabinoid content. When comparing OTC CBD to medically prescribed CBD, it is possible that the ratios will be the same but the content will differ greatly. Pharmaceutically and medically produced cannabis medicines will also have undergone purity testing in laboratory conditions to confirm their contents. This ensures that a patient is receiving the dosage that is prescribed. OTC products are known for sometimes being mislabelled in terms of content.

CBD itself, as an ingredient of an OTC CBD product or medicine, can come in different purities. One mg of 90% pure CBD will contain less CBD than 1mg of 99% pure CBD. That translates into 1ml of 10mg/ml 90% CBD will contain less CBD than 1ml of 10mg/ml of 99% CBD. Some medical cannabis products are based on high pharma grade CBD which makes a difference.

Cannabis Medicine Formulation

As mentioned above, the cannabis ratios and cannabinoid content can be different from medicine to medicine and it is always important to discuss your prescription with your doctor. A products ratio of cannabinoids gives us an indication of what is going on but, what is the concentration, and why do cannabis medicines vary greatly in content of cannabinoids present? Let’s think about the quantity of cannabinoids and if possible, check the purity.

The milligram (mg) of cannabinoids per mL is important to consider when discussing your prescription. High CBD products can have anywhere from 50mg to 200mg of CBD per mL of oil or gram of cannabis flower, and high THC products can include products with THC content greater than 15mg/ml for oil or /100mg dried flower.

Finally, depending on the administration method there may be some consideration when it comes to deciding on dose. The total cannabinoid content per mL or gram maybe be high but that is irrelevant if you are only going to be using a half or quarter of a mL or gram in each dose.

It is not a one size fits all plan and there are many factors to consider when trying to achieve the optimal dose from a prescribed product.
As the availability of products in the UK grows and more suppliers come to market with a wider variety of medicines it is important to understand what you are taking and the potential effects that this may have.

Grow Pharma are also working on ensuring cannabinoid content is presented in a transparent manner by doing six things.

  • Firstly we encourage our producers to let the cannabis ratio reflect the content much better. That means that we ask them to differentiate between a 3:10 and a 30:100. Same ratio but different content.
  • Secondly. we ask them to include the total amount of cannabinoids per ml of oil on the packaging to reflect absolute content again.
  • Thirdly, we ask them to include the total amount of cannabinoids for the whole bottle on the packaging.
  • On our product price list (available to all doctors looking to prescribe) we have included a reference with the actual ratio if not clear in the product name. So, if the 1:10 is actually a 10:100 we have included that for clarity.
    We have also included a column with the total content in mgs of cannabinoids in the bottle
  • Lastly we have added a column with the actual cost per mg of cannabinoids for each medicine.

Of course, there may be other factors to be considered when choosing a certain medicine like the data or evidence behind a certain product or the carrier oil or whether a tincture or a spray (on ethanol base) or an oil is preferred and last but not least a choice between products containing pure isolate cannabinoids or full/broad spectrum products with the minor cannabinoids and terpenes present.

Any decision about cannabis medicines should be made with your prescribing specialist doctor. You can contact our Patient Access Lead Alex Fraser via [email protected] to get you started on your journey, as well as lots of other helpful information about cannabis medicines in the UK.

Alex Fraser

Patient Access Lead, GROW Pharma

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