Almost half of patients who are initial responders to nabiximols oromucosal spray (Sativex) for spasticity in MS have discontinued the medicinal cannabis at 18 months, a European study shows.
An Italian study of 1845 MS patients prescribed the treatment for moderate to severe spasticity resistant to other medications confirmed most patients (81.4%) had the requisite initial response of ≥20% improvement on the 0-10 numerical rating scale (NRS) at four weeks.
However there was a steady decline in use at three months (17.4%) and six months (18%) and a smaller drop off at 12 months (16.1%) and then 18 months (8.9%).
Overall, 48.3% of users had discontinued treatment after 18 months due mainly to loss of efficacy (28.4%) or adverse events (17.1%).
Loss of efficacy was more frequently reported early at three and six months while adverse events became much more important in the longer term at 12 and 18 months.
Patients reported a NRS of 7.8 at baseline which dropped steadily to 4.8 in patients using the treatment at 18 months.
The number of puffs per day remained steady at between six and seven.
“Thus, patients with MS treated on the long term with THC:CBD seemed to not require an increase of dosage to achieve the optimal clinical effect in the routine clinical setting,” the study said.
“The multivariate analysis showed that higher NRS scores at baseline (OR 2.28, 95%CI 1.15 to 6.36, p<0.01) and higher differences of NRS between T1 and T0 (OR 2.11, 95%CI 1.08 to 8.26, p<0.05) were associated to an increased probability to continue the THC:CBD therapy after 18 months.”
“Overall, our data suggest that patients with MS responding better and earlier were more willing to stay on therapy.”
“Thus, special efforts should be made to improve the patient–doctor communication, thus achieving a shared view of the THC:CBD treatment goals and of the strategies to reach them. If any decisions regarding the treatment administration were shared by patients and doctors, early withdrawal could be avoided.”
The findings are consistent with post-marketing registry studies in the UK and Spain and other non-interventional studies.
The findings are reported in the Journal of Neurology, Neurosurgery and Psychiatry.