Can we predict the treatment doses of THC and CBD and does it matter?

Medical cannabis is an increasingly prevalent treatment for a wide variety of indications, yet there is still no uniformly accepted protocol for the titration of cannabinoid doses. We aimed to develop a model to predict the stable THC and CBD dosages after six months of treatment using available baseline patient characteristics.

In this prospective study, we included all consecutive adult patients (age 18 and above) who exclusively used a single method of cannabis delivery. Telephone interviews were conducted six months post-treatment initiation to assess changes in symptoms and side effects. We prospectively analyzed THC and CBD dosages with respect to demographic variables and patient characteristics in two main groups divided according to cannabis administration method - inhalation or sublingual oil.

A total of 3,554 patients were included in the study (2,724 exclusively inhaled cannabis and 830 exclusively consumed cannabis as sublingual oil). The daily THC and CBD doses were significantly higher in the inhalation group than in the sublingual group (p<.001). None of the four models predicting THC and CBD doses in the two groups had satisfactory prediction ability (adjusted R-squared between 0.007 and 0.09). Male gender, unemployed status, tobacco smoking and a lack of concern about cannabis treatment were associated with a higher inhaled THC dose (p<.001).

Models based on patient characteristics failed to accurately predict the final titration doses of CBD and THC for both inhalation and sublingual administration. Clinical guidelines should maintain a highly individual approach for cannabinoid dosing.