Sunday, April 6, 2014
The detection of THC, CBD and CBN in the oral fluid of Sativex patients using two on-site screening tests and LC-MS/MS
Sativex® is an oromucosal spray used to treat spasticity in multiple sclerosis sufferers in some European countries, the United Kingdom, Canada and New Zealand. The drug has also recently been registered by the Therapeutic Goods Administration (TGA) in Australia for treatment of multiple sclerosis. Sativex® contains high concentrations of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), with the former being the subject of random roadside drug tests across Australia to detect cannabis use. This pilot study aims to determine whether or not patients taking Sativex® will test positive to THC using these roadside screening tests. Detectable levels of THC, CBD and cannabinol (CBN) in their oral fluid were also confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The study was a double-blind, placebo controlled design. Oral fluid was tested prior to and immediately after dosing with either Sativex® or placebo at intervals up to 2h after the dose. Two Sativex® doses were studied. The low dose contained 5.4mg THC, the high dose 21.6mg THC. Results indicate that the primary screening test used in Australian roadside drug testing, the DrugWipe® II Twin, often gave a false negative response for THC, even with high concentrations present. However, secondary screening test, Cozart® DDS (used by police after a DrugWipe test gives a positive result), gave true positive results in all cases where patients were being treated with Sativex®. Confirmatory testing showed high concentrations of THC and CBD (>5356ng/mL THC and >3826ng/mL CBD) in the oral fluid shortly after dosing and also elevated concentrations of CBN. Levels dropped quickly but remained at detectable concentrations (>67.6ng/mL) two hours after drug administration. The average concentration ratio of THC/CBD across all positive samples was 1.10 (%RSD 19.9) reflecting the composition of the Sativex® spray. In conclusion, Sativex® users may test positive for THC by roadside drug testing within 2-3h of use. Confirmatory analysis can identify Sativex® treatment through use of THC/CBD ratios, however, these ratios would unlikely be sufficient to differentiate non-medicinal cannabis use from Sativex® use if both are taken concurrently.
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