Threat from carfentanil

Carfentanil is a synthetic opioid that is 10,000 times more potent than morphine and 100 times more potent than fentanyl, which itself is 50 times more potent than heroin. Carfentanil is typically used as a tranquilizing agent for elephants and other large animals. But the DEA says carfentanil is behind an increase in fatal overdoses in the Midwest. Dealers cut the drug into heroin to boost profits.