Cannabis and Phytocannabinoids

Abstract

In many ways, cannabis is central to drug control. It is the most widely consumed illegal substance in most countries. It has been used since antiquity, yet its pharmacology and harmful effects have only come into clear focus in recent years. This in turn has led to several recent shifts in its legal status. Cannabis, cannabis resin and certain phytocannabinoids are Class B controlled drugs but their status has been reviewed many times. THC (Δ9-tetrahydrocannabinol) is the main psychoactive constituent of cannabis. Along with a number of its isomers and stereochemical variants, THC is listed in Schedule I of the United Nations 1971 Convention. These variants are subsumed by a generic definition in the UK but that includes a contentious reference to certain homologues such as tetrahydrocannabivarin. Other major non-psychoactive cannabinoids present in cannabis are cannabinol, cannabidiol and several precursor acids. The specific inclusion of cannabinol in the MDAct in 1971 is regarded as an oversight. Over the past 25–30 years, breeding and intensive indoor cultivation of cannabis have generated products that have a high THC content. In recent years, there has been renewed interest in the use of cannabis for medicinal purposes. Some cannabis-derived products are licensed for a restricted range of conditions. But medicinal cannabis has also become a difficult issue, at least in the UK. Part of the problem resides in the absence of large-scale placebo-controlled clinical trials such as would be mandatory for other potential medicinal products.