MEXICO CITY — In a sign that Mexican traffickers may be having a harder time getting their hands on fentanyl, Mexico said Monday it has seized a second shipment of medicinal fentanyl in glass capsules, suggesting they may have been diverted from a lab, pharmacy or hospital.

Mexican cartels have traditionally received bulk shipments of the powerful synthetic opioid, or the precursor chemicals used to make it, from Asian countries in shipping containers. But lockdowns due to the coronavirus pandemic appear to have temporarily dampened that source.

The fentanyl seizure announced Monday by Mexico's National Guard occurred at a package shipment facility in the central state of Puebla, far from the seaports where the drug has traditionally arrived.

Sniffer dogs detected 240 glass ampules of fentanyl in a styrofoam cooler addressed to someone in the city of Culiacan, the capital of Sinaloa state. Sinaloa is home to the drug cartel of the same name.

The presentation, in glass ampules, is generally used by doctors to inject fentanyl as a pain reliever. Traffickers are generally more interested in powdered forms of the drug they can cut and press into pills.

The U.N. Office on Drugs and Crime said in a report in March that "there are reports that the reduction in trade from South-East Asia has limited the supply of chemical precursors in Mexico, where it seems to have disrupted the manufacture of methamphetamine and fentanyl."

Each of the ampules seized Monday contain only a small amount of fentanyl, but the drug is many times stronger than heroin.

It was the second such seizure in Mexico since the pandemic lockdown began here in March. In May, Guard members seized a similar shipment of 60 fentanyl ampules in the north-central state of Queretaro.

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