Naloxone shows therapeutic promise after ischemic stroke

By Paul Basilio, MDLinx
Published April 19, 2018

Key Takeaways

A new study published in eNeuro showed that administration of intranasal naloxone following a stroke can promote short-term functional recovery and reduce microglia/macrophage activation in rats. This is the first study to show a promising application of the drug for treatment of ischemic stroke.

The opiate antagonist naloxone has been used for opioid overdose for nearly 50 years, and prior research has shown that the drug’s modulation of immune and glial responses has the potential for therapeutic benefit in stroke. However, the drug’s effects had not been tested poststroke. 

This study employed a rat model of focal cortical ischemic stroke. Intranasal naloxone was administered starting on poststroke day 1 and continued every 12 hours for 7 days, for a total of 14 administrations. Vehicle and no-treatment groups were included as controls in behavioral assays.

Results showed that on poststroke days 10 and 14, body asymmetry and neurologic deficits were significantly reduced in a dose-dependent manner in the naloxone group. The naloxone group also saw improved locomotor activity at day 14 and behavioral recovery on days 10 and 14.

The treatment group showed reduced infarction size on day 14. Delayed neuronal death was prevented in the ipsilateral thalamus. No decrease in body weight was noted.

In contrast, no statistically significant differences between the naloxone and vehicle groups were seen in pretreatment with naloxone before the stroke or delayed administration at 3 days following the stroke. No differences between the two groups were noted in extended administration of naloxone for 14 days.

“We show for the first time that intranasal poststroke administration of naloxone enantiomers reduces inflammation and hastens recovery during short-term behavioral monitoring,” the authors wrote. “Our data support a therapeutic window for initiation of twice-daily naloxone treatment between 16 and 36 hours poststroke and continuing the treatment for 7 days.”

Although more research is required, this preclinical study is an introductory step that lays the groundwork for a therapeutic drug to improve recovery from stroke in humans.

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