Overview of Sativex for MS spasticity: three pivotal clinical trials | Research

The takeaway

Across three pivotal trials involving over 1,000 patients, Sativex consistently reduced MS spasticity scores compared to placebo, with mild and transient side effects.

Read this if you have MS spasticity and want to see the clinical trial data behind Sativex.

47% of patients were initial responders in the largest trial

What the researchers found

This review summarized data from three pivotal randomized controlled trials of Sativex for MS-related spasticity. The first trial (189 patients, 6 weeks) showed a significant spasticity score reduction with Sativex versus placebo (-1.18 vs -0.63, p=0.048). The second trial (337 patients, 15 weeks) confirmed the finding (-1.3 vs -0.8, p=0.035).

The third trial used an innovative design: 572 patients first tried Sativex openly, and the 47% who responded (20% or greater improvement) were then randomized to continue Sativex or switch to placebo. Responders who continued Sativex maintained their improvement, while those switched to placebo worsened (p=0.0002).

No tolerance, withdrawal syndrome, or evidence of misuse or abuse was reported across trials. Side effects were mild-to-moderate and transient, primarily dizziness, fatigue, and somnolence.

Why it matters

This represented the strongest clinical trial evidence at the time for any cannabis-based medicine. The enriched enrollment design of the third trial was particularly important because it demonstrated that identifying responders first could improve treatment efficiency.

The numbers in context

Trial 1: 189 patients, 6 weeks, p=0.048. Trial 2: 337 patients, 15 weeks, p=0.035. Trial 3: 572 patients, 47% initial responders, p=0.0002 for sustained efficacy. No tolerance or withdrawal reported.

How the study worked

Review of three pivotal randomized, placebo-controlled clinical trials of Sativex oromucosal spray in MS patients with resistant spasticity. Combined enrollment exceeded 1,000 patients. Primary endpoint was the 0-10 NRS spasticity score.

What this study cannot tell us

Review by a single author. The NRS spasticity scale is subjective. The enriched enrollment design in trial 3, while practical, selects for patients who respond and may overestimate effect size for the general MS population.

How to read the evidence

Review of three pivotal RCTs with combined enrollment exceeding 1,000 patients. Represents strong clinical evidence for this indication.

When this study was published

Published in 2011. Sativex has since been approved in over 25 countries for MS spasticity.

The bigger picture

These trials formed the regulatory basis for Sativex approval in multiple countries. The enriched enrollment design became a model for subsequent cannabis medicine trials, addressing the challenge of variable individual responses.

Questions still open

What predicts which MS patients will be Sativex responders? Does long-term use maintain efficacy beyond the trial periods? Could the enriched design approach improve other cannabis medicine trials?

Common questions

How effective is Sativex for MS spasticity?

About 47% of patients in the largest trial showed meaningful improvement (20% or better) in spasticity scores. For those who respond, the benefits were sustained over months of treatment. Not everyone responds, which is why a trial period is recommended.

Does Sativex cause a high?

No significant intoxication was reported in clinical trials. The most common side effects were dizziness, fatigue, and somnolence, which were generally mild to moderate and could be reduced by gradually increasing the dose.

Read the original research

Sativex(®) (tetrahydrocannabinol + cannabidiol), an endocannabinoid system modulator: basic features and main clinical data.

Expert review of neurotherapeutics, 11(4 Suppl), 15-9

View on PubMed ↗

Citation

Vermersch, Patrick. (2011). Sativex(®) (tetrahydrocannabinol + cannabidiol), an endocannabinoid system modulator: basic features and main clinical data.. Expert review of neurotherapeutics, 11(4 Suppl), 15-9.