In the spring of 1998, the British government licensed a company calledÂ GW Pharmaceuticals to grow cannabis and develop a precise and consistent extract for use in clinical trials. GWâ€™s co-founder Geoffrey Guy, MD, was convincedâ€“and had convinced the Home Officeâ€“that by using CBD-rich plants, GW could produce a cannabis-based medicine with little or no psychoactiveÂ effect.
That summer Guy described his approach at a meeting of the International Cannabinoid Research Society (ICRS). In addition to countering the psychoactivity of THC, Guy said, CBD conferred benefits of its own. GW got its CBD-rich strains by acquiring the genetic library of HortaPharm, a Dutch seed company run by American expatriate horticulturists, David Watson and RobertÂ Clarke.
CBD-rich cannabis has a long history of being used to treat health problems. Queen Victoria used CBD-rich cannabis for menstrual cramps in the 19th century. Animal studies had long suggested that CBD lessens anxiety and reduces the severity and frequency of seizures. But, up until a few years ago, CBD-rich strains were generally not available to cannabis users in California and other areas. Generations of breeding marijuana for maximum THC and a strong â€śhighâ€ť had reduced the CBDÂ to trace amountsÂ in most cannabis strains in Northern California, Americaâ€™s cannabisÂ breadbasket.
Dr. Tod Mikuriya, founder of the Society of Cannabis Clinicians,Â expressed hope that â€śour Burbanks in the hillsâ€ť of Northern California would develop CBD-rich strains if and when analytic labs began serving the medical cannabisÂ industry.
As the years went by, more and more promising scientific studies involving CBD were described at meetings of the ICRS, theÂ International Association for Cannabinoid Medicine,Â andÂ Patients Out of Time. Some California doctors kept abreast of the research andÂ Oâ€™Shaughnessyâ€™sÂ reported on it, but we were merely observers, not participants, until the fall of 2009, when Oaklandâ€™sÂ Steep Hill LaboratoryÂ tested cannabis samples provided byÂ Harborside Health CenterÂ and found a few strains with more CBD than THC.
Before long, several dozen labs in medical marijuana states were calibrating cannabinoid ratios and identifying the occasional CBD-rich strain. For data collection purposes, we initially defined â€śCBD-richâ€ť as 4% or more by dry weight. In addition to balanced strains with roughly equal amounts of CBD and THC, a handful of CBD-dominant strainsâ€“with 20-to-1 CBD:THC ratios or higher were discovered, fostering a cottage industry of CBD-rich concentrates, oil extracts, and other CBD-richÂ products.
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