This screen grab from an advertisement opposing a proposition to legalize marijuana in Arizona shows that it was funded in part by pharmaceutical company Insys Therapeutics. (YouTube) Christopher IngrahamWashington Post Insys Therapeutics, a pharmaceutical company that was one of the chief financial backers of the opposition to marijuana legalization in Arizona last year, received Marijuana Stocks preliminary approval from the Drug Enforcement Administration this week for Syndros, a synthetic marijuana drug. Insys gave $500,000 last summer to Arizonans for Responsible Drug Policy, the group opposing marijuana legalization in Arizona. The donation amounted to roughly 10 percent of all money raised by the group in an ultimately successful campaign against legalization. Insys was the only pharmaceutical company known to be giving money to oppose legalization last year, according to a Washington Post analysis of campaign finance records. Syndros is a synthetic formulation of THC, the main psychoactive component in the cannabis plant. It was approved by the FDA last summer to treat nausea, vomiting and weight loss in cancer and AIDS patients. The DEA approval places Syndros and its generic formulations in Schedule II of the Controlled Substances Act, indicating a “high potential for abuse.” Other Schedule II drugs include cocaine, morphine and many prescription painkillers. Whole-plant marijuana remains in Schedule I of the CSA, an even stricter regulatory category that designates a lack of medically accepted use in addition to a high abuse potential.