This study investigated the antispasticity potential of Sativex in mice. Chronic relapsing experimental allergic encephalomyelitis was induced in adult ABH mice resulting in hind limb spasticity development. Vehicle, Sativex, and baclofen (as a positive control) were injected intravenously and the “stiffness” of limbs assessed by the resistance force against hind limb flexion. Vehicle alone caused no significant change in spasticity. Baclofen (5 mg/kg) induced approximately a 40% peak reduction in spasticity. Sativex dose dependently reduced spasticity; 5 mg/kg THC + 5 mg/kg CBD induced approximately a 20% peak reduction; 10 mg/kg THC + 10 mg/kg CBD produced approximately a 40% peak reduction in spasticity. Sativex has the potential to reduce spasticity in an experimental mouse model of multiple sclerosis (MS). Baclofen reduced spasticity and served as a positive control. Sativex (10 mg/kg) was just as effective as baclofen, providing supportive evidence for Sativex use in the treatment of spasticity in MS.
BDSs containing high levels of either THC (69.3%) or CBD (66.5%) were supplied by GW Pharma Ltd. and held under a Home Office Licence to Possess under The Misuse of Drugs Act 1971. These were combined in a 1 : 1 ratio based on the amount of principal cannabinoid within each BDS, then dissolved in ethanol prior to addition of Cremophor (Sigma, Poole Dorset) and then phosphate-buffered saline (PBS) in a ratio of (1 : 1 : 18). This closely resembles the composition of Sativex, where the same BDSs are formulated in a 50 : 50 mixture of ethanol and propylene glycol, and for simplicity is referred to as Sativex throughout this paper. Baclofen was purchased from RBI/Sigma (Poole, UK) and was dissolved in PBS. All compounds were injected intravenously in the tail vein using a 30 g needle in a volume of 0.1 mL at doses of 5 mg/kg or 10 mg/kg Sativex and 5 mg/kg baclofen. The doses of Sativex used were chosen on the basis of previous studies [18, 19] and represent a reasonable equivalence to the clinical dose range used in human patients.
Current forms of treatment for people suffering from MS-related spasticity include physical therapy, which involves stretching and hydrotherapy, employment of mechanical aids, such as braces, use of chemical blocks including phenol injected into the muscles or intrathecally, or in extreme cases, surgery [4, 5]. The most common form of treatment is the use of oral medications, but current therapy is often associated with dose-limiting adverse side-effects. Approximately 37% of MS patients take the most commonly prescribed antispasticity agents  including baclofen, dantrolene, tizanidine, diazepam, gabapentin, botulinum toxin, and phenol, but many clinicians report that a proportion of these patients are not being adequately treated due to adverse effects of these medications.
Cannabis medicines may contain only delta-9-tetrahydrocannabinol (THC) or cannabidiol (CBD), or a combination of both THC and CBD in different ratios. For information about scheduling of cannabis and tetrahydrocannabinols in the Poisons Standard, refer to the Therapeutic Goods Administration (TGA).
Cannabis medicines registered in Australia
Although approval by the Australian Government’s TGA is not required to prescribe Sativex® (nabiximols) or Epidyolex®, a NSW Health authority must be obtained to prescribe Schedule 8 cannabis medicines to certain patient groups. Further details can be found on the Pharmaceutical Services website.
Cannabis medicines registered overseas
There are a limited number of cannabis medicines that have been formally assessed for quality, safety and efficacy, either in Australia or by an overseas medicines regulator.