The Trial That Made Cannabis a Real Prescription Medicine
A randomized, double-blind, placebo-controlled, parallel-group, enriched-design study of nabiximols (Sativex), as add-on therapy, in subjects with refractory spasticity caused by multiple sclerosis
Bottom Line
Sativex, a cannabis-derived mouth spray, significantly reduced MS spasticity in treatment-refractory patients — becoming the first cannabis medicine approved through full pharmaceutical regulation.
Why It Matters
This was the pivotal trial that led to Sativex becoming the world's first cannabis-derived prescription medicine approved through the full pharmaceutical regulatory pathway — now approved in 25+ countries for MS spasticity.
The Backstory
Multiple sclerosis attacks the nervous system's wiring. As the immune system strips myelin from nerve fibers, the signals that tell muscles when to contract and when to relax become garbled. The result is spasticity — muscles that won't let go, that tighten involuntarily, that wake you at 3 AM with spasms powerful enough to throw you out of bed.
For decades, the treatment options were blunt instruments. Baclofen, the first-line drug, works by suppressing the entire spinal reflex arc — reducing spasticity, but also reducing the muscle tone you need to stand and walk. Tizanidine sedates. Diazepam creates dependence. Dantrolene weakens muscles system-wide. All of them treat spasticity by making the muscles weaker, not by fixing the garbled signals. And for many patients — roughly half — they simply don't work well enough.
This is the disease that produced the most commercially successful cannabis medicine in history.
The Drug That Couldn't Exist
Sativex (nabiximols) shouldn't have been possible. A botanical extract — derived from actual cannabis plants, not synthesized in a lab — navigating the full pharmaceutical regulatory gauntlet? In a legal environment where the source plant was Schedule I?
GW Pharmaceuticals, founded in 1998 by Geoffrey Guy, a British physician who believed cannabis medicines could be developed to pharmaceutical standards, built the company around this bet. They obtained a UK Home Office license to cultivate cannabis, developed standardized plant lines, and created an oromucosal spray that delivered a precise 1:1 ratio of THC and CBD with each actuation: 2.7 mg THC and 2.5 mg CBD per spray.
The key regulatory innovation was the delivery system. By using an oromucosal spray with metered dosing, GW could demonstrate pharmaceutical-grade consistency, reproducible pharmacokinetics, and titratability — the same qualities regulators demand of any prescription drug. Patients could adjust their dose spray by spray, finding the minimum effective level. This wasn't a joint or an edible. It was medicine.
But GW needed a disease indication where cannabis had clear therapeutic potential, where existing treatments were inadequate, and where regulatory agencies would be sympathetic. MS spasticity was the obvious choice.
The Enriched-Enrollment Design
Novotna's trial used a study design that was both clever and clinically realistic — and which had never before been applied to an oral antispasticity agent.
The enriched design was controversial among purists who preferred traditional parallel-group randomization. But it had a powerful clinical argument: in real-world practice, no doctor would continue prescribing Sativex to a patient who showed no benefit after a month. The enriched design tested the drug the way it would actually be used — try it, keep it if it works, stop it if it doesn't.
The 47.6% initial response rate was itself informative. It meant roughly half of refractory MS spasticity patients — people who had already failed other treatments — got meaningful relief from Sativex within four weeks. For a condition with limited options, that's a substantial response rate.
The Numbers
p = 0.0002
Primary endpoint significance — the difference in spasticity NRS scores between Sativex and placebo groups during the 12-week randomized phase was highly statistically significant.
In the initial open-label phase, mean spasticity scores dropped from 6.91 to 3.9 (a 44% reduction). During randomization, Sativex patients maintained this improvement while placebo patients lost ground. Secondary endpoints including sleep quality and patient global impression of change also significantly favored Sativex.
Novotna et al. (2011), Eur J Neurol
The study enrolled patients from multiple countries across Europe, making it a multinational effort. The patient population was carefully defined: MS patients with moderate-to-severe spasticity (NRS score of 4 or higher) that had not been adequately controlled by existing antispasticity medications. These were treatment-refractory patients — the hardest cases.
Secondary endpoints reinforced the primary finding:
The Regulatory Cascade
The Novotna trial was the pivotal study that led to Sativex's regulatory approval — and the approval cascade that followed was remarkably rapid for a cannabis-derived medicine.
Sativex is now approved in over 25 countries for MS spasticity. Notably, it has never been approved in the United States — where the Schedule I classification of cannabis has made the regulatory pathway more complex. US Phase 3 trials began in 2020, and approval remains pending.
The irony is thick: the same molecule (THC) that millions of Americans buy legally at state-licensed dispensaries cannot be prescribed as a pharmaceutical because the federal government classifies it alongside heroin. Sativex would be the first THC-containing pharmaceutical approved by the FDA — if it ever gets there.
Why Sativex Works: The Endocannabinoid System and Spasticity
The biological rationale for cannabis treating spasticity is unusually strong. CB1 receptors are densely expressed in the basal ganglia, cerebellum, and spinal cord — precisely the circuits that regulate muscle tone. Endocannabinoids serve as retrograde messengers at both excitatory and inhibitory synapses, modulating the balance between muscle contraction and relaxation.
In MS, demyelination disrupts this balance. Spasticity arises because the inhibitory signals that tell muscles to relax don't get through. THC, by activating CB1 receptors throughout the motor circuitry, partially restores the inhibitory tone that MS has stripped away — but through a different mechanism than baclofen (which works on GABA-B receptors). This means Sativex can work additively with existing antispasticity drugs, targeting a different part of the circuitry.
The 1:1 THC:CBD ratio is deliberate. CBD modulates THC's psychoactivity, reducing the anxiety and cognitive impairment that pure THC would produce. It also has independent anti-inflammatory and neuroprotective properties that may address MS pathology beyond just spasticity. The entourage effect — the concept that whole-plant extracts work differently than isolated compounds — was built into Sativex's design from the beginning.
The Significance for Cannabis Medicine
The Novotna trial proved something that many thought impossible: that a cannabis-derived medicine could satisfy the full evidentiary requirements of pharmaceutical regulation. It went through Phase I, II, and III trials. It had a defined mechanism. It demonstrated efficacy in a randomized, placebo-controlled design. It had a characterized side-effect profile and drug interaction data. It was manufactured to pharmaceutical standards.
Myth vs. Reality
Cannabis can't be studied rigorously because it's a plant, not a drug — you can't standardize it or do proper clinical trials.
Sativex (nabiximols) completed the full pharmaceutical development pathway — from preclinical studies through Phase III randomized controlled trials — using a standardized whole-plant cannabis extract. It is approved as a prescription medicine in over 25 countries. The barrier to cannabis pharmaceutical development is regulatory, not scientific.
The Evidence
Novotna et al. (2011) is one of multiple Phase III RCTs of Sativex. The enriched-enrollment design met EMA regulatory standards. GW Pharmaceuticals cultivated standardized cannabis plants under pharmaceutical Good Manufacturing Practice (GMP). Each spray delivers a precise, reproducible dose.
Novotna et al. (2011), Eur J Neurol; GW Pharmaceuticals regulatory filings
For the broader cannabis medicine debate, Sativex established the precedent. If cannabis can be standardized, tested, and approved for MS spasticity, the same pathway is open for other indications. GW Pharmaceuticals later used the same approach to develop Epidiolex (pure CBD) for epilepsy — the first cannabis-derived drug approved by the FDA.
For MS patients specifically, Sativex offered something the existing drugs didn't: meaningful relief for many treatment-refractory cases, with a side-effect profile that patients could tolerate. Our guide to cannabis and multiple sclerosis covers the full picture — including what Sativex does and doesn't do, and how it fits alongside other MS treatments.
Key Takeaways
A randomized, double-blind, placebo-controlled, parallel-group, enriched-design study of nabiximols (Sativex), as add-on therapy, in subjects with refractory spasticity caused by multiple sclerosis
Novotna A, Mares J, Ratcliffe S, Novakova I, Vachova M, Zapletalova O, Gasperini C, Pozzilli C, Cefaro L, Comi G, Rossi P, Ambler Z, Stelmasiak Z, Erdmann A, Montalban X, Klimek A, Davies P; Sativex Spasticity Study Group () · European Journal of Neurology
Cite this study
Novotna A, Mares J, Ratcliffe S, Novakova I, Vachova M, Zapletalova O, Gasperini C, Pozzilli C, Cefaro L, Comi G, Rossi P, Ambler Z, Stelmasiak Z, Erdmann A, Montalban X, Klimek A, Davies P. (2011). A randomized, double-blind, placebo-controlled, parallel-group, enriched-design study of nabiximols (Sativex), as add-on therapy, in subjects with refractory spasticity caused by multiple sclerosis. European Journal of Neurology. https://doi.org/10.1111/j.1468-1331.2010.03328.x