Synthetic cannabinoids popularly marketed as "K2" and "Spice" are widely available at gas stations and convenience stores in many states, yet addictions researchers know almost nothing about the long-term consequences of using these drugs, according to Ryan Vandrey, PhD, a marijuana researcher at the Johns Hopkins University School of Medicine.

The products are commonly marketed as incense and labeled "not for human consumption" on the packaging, but buyers smoke the products like marijuana, Vandrey said during a presentation at APA's 2011 Annual Convention. The drugs are made by spraying synthetic cannabinoids on ground-up plant material. Spice and K2 are the most popular brands, but dozens more are on the market, he said.

"These products are used as an alternative to smoking marijuana, especially among people subject to routine drug testing," Vandrey said.

In one clue to the substance's increasing prevalence, poison control centers reported 13 calls referencing the products in 2009. In the first seven months of this year, that number had already reached 3,787, he said.

"Is overdose more likely with these substances, or are they more dangerous than marijuana? We really don't know," he said.

The Drug Enforcement Administration listed five synthetic cannabinoid compounds commonly used in these drugs on the federal schedule of controlled dangerous substances in March, but manufacturers continue marketing the product using synthetic cannabinoid variations not yet scheduled by the DEA, he said. 

In an online survey Vandrey conducted, published online in the journal Drug and Alcohol Dependence in August, he found that 87 percent of 168 users reported they obtained the drug legally, through gas stations, head shops and convenience stores; just 2 percent said they got it illicitly by going to a drug dealer who sells other illegal drugs such as marijuana, cocaine and heroin. About 15 percent reported using the substance daily and 12 percent of respondents met the dependence criteria of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), he said. Regular users reported an average of 67 uses in the past year, he said.

While some states have banned K2 and Spice, users can also order the products online. Some online suppliers will not ship the products to buyers in states that have banned the products, while others will, Vandrey said.

—C. Munsey