Medicinal Δ<sup>9</sup>-tetrahydrocannabinol (dronabinol) impairs on-the-road driving performance of occasional and heavy cannabis users but is not detected in <fc>S</fc>tandard <fc>F</fc>ield <fc>S</fc>obriety <fc>T</fc>ests
Authors: Bosker, Wendy M.; Kuypers, Kim P. C.; Theunissen, Eef L.; Surinx, Anke; Blankespoor, Roos J.; Skopp, Gisela; Jeffery, Wayne K.; Walls, H. Chip; Leeuwen, Cees J.; Ramaekers, Johannes G.
Source: Addiction, Volume 107, Number 10, 1 October 2012 , pp. 1837-1844(8)
Abstract:<title type="main">Abstract</title> <section xml:id="add3928-sec-0001"> <title type="main">Aims</title> The acute and chronic effects of dronabinol [medicinal Δ9-tetrahydrocannabinol (<fc>THC</fc>)] on actual driving performance and the <fc>S</fc>tandard <fc>F</fc>ield <fc>S</fc>obriety <fc>T</fc>est (<fc>SFST</fc>) were assessed. It was hypothesized that occasional users would be impaired on these tests and that heavy users would show less impairment due to tolerance. </section> <section xml:id="add3928-sec-0002"> <title type="main">Design, setting and participants</title> Double-blind, placebo-controlled, randomized, three-way cross-over study. Twelve occasional and 12 heavy cannabis users (14 males/10 females) received single doses of placebo, 10 and 20 mg dronabinol. </section> <section xml:id="add3928-sec-0003"> <title type="main">Measurements</title> Standard deviation of lateral position (<fc>SDLP</fc>; i.e. weaving) is the primary measure of road-tracking control. Time to speed adaptation (<fc>TSA</fc>) is the primary reaction-time measure in the car-following test. Percentage of impaired individuals on the <fc>SFST</fc> and subjective high on a visual analogue scale were secondary measures. </section> <section xml:id="add3928-sec-0004"> <title type="main">Findings</title> Superiority tests showed that <fc>SDLP</fc> (<fc>P</fc> = 0.008) and <fc>TSA</fc> (<fc>P</fc> = 0.011) increased after dronabinol in occasional users. Equivalence tests demonstrated that dronabinol-induced increments in <fc>SDLP</fc> were bigger than impairment associated with <fc>BAC</fc> of 0.5 mg/ml in occasional and heavy users, although the magnitude of driving impairment was generally less in heavy users. The <fc>SFST</fc> did not discriminate between conditions. Levels of subjective high were comparable in occasional and heavy users. </section> <section xml:id="add3928-sec-0005"> <title type="main">Conclusions</title> Dronabinol (medicinal tetrahydrocannabinol) impairs driving performance in occasional and heavy users in a dose-dependent way, but to a lesser degree in heavy users due possibly to tolerance. The <fc>S</fc>tandard <fc>F</fc>ield <fc>S</fc>obriety <fc>T</fc>est is not sensitive to clinically relevant driving impairment caused by oral tetrahydrocannabinol. </section>
Document Type: Research article
Publication date: 2012-10-01