Hemp plants grow at Meigs Farm, part of Throckmorton Purdue Agricultural Center south of Lafayette. After the plant was legalized for research purposes in 2014, a Purdue professor planted in June 2015 Indiana’s first industrial hemp in 80 years.(Photo: Joseph Paul/Journal & Courier)

Trace amounts of the psychoactive ingredient in marijuana could soon be legal for Indiana epilepsy patients under a measure headed to Gov. Eric Holcomb's desk.

House Bill 1148 would legalize the use of cannabidiol for patients with treatment-resistant epilepsy. The oil is derived from the cannabis plant but would be allowed to contain only up to .3 percent Tetrahydrocannabinol, or THC, the ingredient in marijuana that produces a "high."

Advocates have tried to distance the legislation from efforts to legalize marijuana for medical and recreational purposes.

"This is not the gateway to medical marijuana. This is not the gateway to recreational marijuana," said Sen. Randy Head, R-Logansport, who carried the bill in the Senate. "This is a gateway for parents whose children have a hundred seizures a day or adults in the population — less than one third of one percent — who have epilepsy that can’t be treated by other means."

The bill won surprisingly strong support from the Republican-dominated General Assembly, where opposition to marijuana legalization has been robust. The Senate approved the measure 36-13 on Thursday and the House voted unanimously for it Friday.

The measure now goes to Gov. Eric Holcomb, who can sign it into law, let it become law without his signature or veto it.

Approval came after hearings that included impassioned pleas from the parents and grandparents of children suffering from epilepsy, including a pharmacist and circuit court judge.

Law enforcement officials expressed concerns about previous versions of the bill, fearing the legislation could lead to medical or recreational marijuana legalization. But they did not object to the version that passed Friday.

Unless Holcomb vetoes the bill, Indiana will join 17 other states where products low in THC and high in cannabidiol have been approved for medical purposes in some circumstances, according to the National Conference on State Legislatures.