Missouri Gov. Jay Nixon has signed legislation aimed at expanding access to an anti-overdose medicine for opiates.

When it takes effect Aug. 28, pharmacists will be able to sell the drug naloxone. It blocks potentially deadly effects of heroin or opioid prescription pill overdoses.

The measure also will allow people to carry naloxone without a prescription. Those who use it in good faith to help someone overdosing will be legally protected.

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