A pharmacokinetic study of oromucosal THC spray in 20 older medical patients with poor appetite found extremely large inter- and intra-individual variability (40-152% CV), meaning the same dose produced wildly different blood levels across patients.
Geriatricians prescribing cannabis-based medicines, pharmacologists studying cannabinoid dosing, and older patients using THC products.
Variability of 40-152% CV in THC absorption among older patients
What the researchers found
THC pharmacokinetics in older patients showed enormous variability, with coefficient of variation ranging from 40.2% to 152% across pharmacokinetic parameters. A one-compartment model best described THC, with apparent clearance through conversion to THC-OH at 765 L/h. No physiological characteristics including kidney function or body composition significantly influenced pharmacokinetics.
Why it matters
Older adults are an increasingly important population for cannabis-based medicines, yet almost all pharmacokinetic data comes from younger, healthy volunteers. The extreme variability found here means dosing guidelines developed in younger populations may be unreliable for elderly patients.
The numbers in context
20 older patients. Two doses of 2.7 mg THC per spray (2-3 sprays each). THC clearance to THC-OH: 765 L/h. Clearance by other pathways: 162 L/h. Inter- and intra-individual variability: CV 40.2-152%. Absorption modeled with 3 transit compartments.
How the study worked
Twenty older medical patients with poor appetite received two fixed doses of Sativex oromucosal spray (2-3 sprays of 2.7 mg THC each, 4 hours apart). Blood samples were collected for 8 hours. Non-linear mixed-effects modeling developed population pharmacokinetic models for THC and its active metabolite THC-OH.
What this study cannot tell us
Small sample of 20 patients. Single oromucosal product (Sativex). Eight-hour blood sampling may miss later pharmacokinetic phases. Poor appetite itself may affect oromucosal absorption. No comparison with younger adults in the same study.
How to read the evidence
Preliminary: small pilot pharmacokinetic study in 20 patients with a single product and limited sampling duration.
When this study was published
Published 2026.
The bigger picture
As cannabis-based medicines expand into indications like appetite loss, pain, and spasticity in older adults, this study provides the first dedicated pharmacokinetic data in this population and reveals a dosing challenge that will need individualized approaches.
Questions still open
- What drives the enormous variability in older adults? Would alternative delivery routes (oral capsules, sublingual oils) show less variability? How should clinicians approach dosing when the same dose can produce 15-fold different blood levels?
Common questions
Does age affect how THC is absorbed?
Can doctors predict how an older patient will respond to THC?
Read the original research
Population pharmacokinetic modelling revealed large variability in oromucosal absorption of Δ9-tetrahydrocannabinol in older patients with poor appetite.
British journal of clinical pharmacology, 92(2), 504-514
Citation
Storgaard, Ida Klitzing; Nielsen, Rikke Lundsgaard; Houlind, Morten Baltzer; Bornæs, Olivia; Christensen, Louise Westberg Strejby; Andersen, Aino Leegaard; Juul-Larsen, Helle Gybel; Jørgensen, Lillian Mørch; Breindahl, Torben; Jawad, Baker Nawfal; Altintas, Izzet; Andersen, Ove; Lund, Trine Meldgaard. (2026). Population pharmacokinetic modelling revealed large variability in oromucosal absorption of Δ9-tetrahydrocannabinol in older patients with poor appetite.. British journal of clinical pharmacology, 92(2), 504-514. https://doi.org/10.1002/bcp.70284
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