SAN DIEGO—Giving IV magnesium to patients with stroke soon after the start of symptoms, in an attempt to protect brain cells deprived of oxygen, may not improve stroke-related disability three months later, according to research presented at the 2014 International Stroke Conference. Paramedics can deliver IV medications successfully to most stroke patients within an hour after symptoms begin.
“We hoped magnesium would be beneficial, but in any case the study was a success in demonstrating we can get a drug to patients in this early time frame when there is the greatest amount of threatened brain tissue that might still be saved,” said Jeffrey L. Saver, MD, Professor of Neurology and Director of the Stroke Center at the University of California, Los Angeles. “There are lots of other promising agents in the pipeline that could be helpful, and we now have a system for testing and using them.”
Investigators conducted the Field Administration of Stroke Therapy—Magnesium (FAST-MAG) phase III clinical trial to determine whether IV magnesium, a potential neuroprotective agent, could be delivered in a timely manner and whether it would improve patients’ neurologic outcomes. Between 2005 and 2012, paramedics evaluated and began infusions of study medications for 1,700 patients (42.7% female, average age 69) within two hours of symptom onset. Paramedics administered a loading dose (4 g over 15 minutes) of magnesium sulfate or matched saline placebo. After patients arrived at an emergency department, clinicians administered a maintenance infusion of 16 g of magnesium or matched placebo over 24 hours.
IV magnesium was safe and resulted in no more serious adverse reactions than placebo infusions. Magnesium provided no benefit in outcome, however. Ninety days after the stroke, the average level of disability in patients receiving magnesium and in those receiving placebo was 2.7 on the modified Rankin scale. The median time for receiving treatment was 45 minutes after symptoms began, and 74% of patients were started on treatment within an hour.
“There are several [tests of other] promising compounds already being planned, and others queuing to be tested,” said Dr. Saver. Investigators in Denmark are conducting a prehospital study during which paramedics in the ambulance perform ischemic perconditioning (ie, making the limbs briefly ischemic). Researchers in the United Kingdom are studying glyceryl trinitrate administration in the ambulance, and Canadian researchers are preparing to study NA-1 treatment in the ambulance.
—Erik Greb