Everything you need to know about the newest threat in the US overdose epidemic - elephant sedative

This is fentanyl. It looks like any other prescription painkiller — but it isn't.

Fentanyl, which is also available in a patch or liquid, is 80 to 100 times more powerful than morphine and about 40 to 50 times more potent than 100% pure heroin.

Source: Centers for Disease Control and Prevention

Still, the drug belongs to a larger class of drugs, known as opioid painkillers, which includes prescription drugs like OxyContin and Vicodin. These drugs work by capitalizing on our body's natural pain-relief system, and can result in a surging sense of euphoria.

Since 1999, overdose deaths involving opioid painkillers have quadrupled. In 2014 alone, more than 14,000 people died from overdoses involving the drugs.

Source: Centers for Disease Control and Prevention

Now, meet carfentanil. It's of the most potent opioids known to investigators, according to the Associated Press. And it's an elephant tranquilizer — hence the fuzzy pink tails on the needles pictured below:

Source: Associated Press

The drug, known by the trade name Wildnil, is marketed as a general anesthetic for large animals. The maximum-strength fentanyl that is currently legal for prescription use is called sufentanil, and it's roughly 0.05-0.1 times as potent as Wildnil.

Source: Journal of the British Veterinary Association; Journal of Clinical Pharmacy

Wildnil is so strong, in fact, that veterinarians don protective gear including a face shield and gloves before administering it to animals, Rob Hilsenroth, director of the American Association of Zoo Veterinarians, told the AP. Otherwise, they typically shoot darts filled with the drug at animals from long distances, as in the photo below:

Source: Associated Press

Yet it's Wildnil — otherwise called carfentanil — and not sufentanil, that authorities say is now showing up on the streets. As of last week, carfentanil was suspected in several overdosing spates across the US, where it's allegedly being sold as heroin.

Source: Associated Press

Cases involving alleged carfentanil have sprouted up in cities in Kentucky, Ohio, and Florida.

But authorities still don't know where the drug is originating. People may be smuggling it in from abroad or made in US labs. DEA agents say the drug hasn't popped up in their tests recently, but it is being sold online by several companies in China.

Carfentanil is deadly, especially when obtained on the street where there's no way to know exactly what's inside. As an opioid painkiller, the drug slows down breathing and the functions of the central nervous system. “They know that’s the high that’ll take you right up to the edge, maybe kill you, maybe not,” Joseph Pinjuh, chief of the Organized Crime Drug Enforcement Task Force and narcotics unit for the US attorney in Cleveland, told AP.