DES MOINES, Iowa (AP) — An already specific bill legalizing the use of oil derived from marijuana to treat chronic epilepsy has been further narrowed by a legislative panel. The House Public Safety Committee amended and approved the measure Tuesday, 13-5. It is now eligible for floor debate.

The legislation requires patients and caregivers to acquire a registration card through Iowa’s Department of Public Health, per a written recommendation from a neurologist. The oil would have to be obtained in another state that produces it.

Amendments adopted by the panel would limit the amount of the oil in a patient or caregiver’s possession, require rules for temporary registration cards and charge the University of Iowa with the task of conducting a clinical study to determine how the drug works and whether there are side effects.