Distribution restrictions put in place by major pharmaceutical companies in the United States against misuse of their medicines and export regulations instituted by the European Union have made it increasingly difficult for states to obtain supplies of drugs for use in executions. However, despite these restrictions, some states have obtained pharmaceutical products manufactured by these companies for use in lethal injections.

The Influence reports that the Commonwealth of Virginia obtained lethal injection drugs produced by the pharmaceutical company Mylan—rocuronium bromide, which induces paralysis, and potassium chloride, which stops the heart—from a large North Carolina based drug wholesaler, Cardinal Health. Mylan wrote to the Virginia prisons seeking assurances that use of its medicines in the future would not be diverted to any “purpose inconsistent with their approved labeling and applicable standards of care.”

Recently, the Associated Press discovered that the supply of vecuronium bromide obtained by the Arkansas Department of Correction was produced by a subsidiary of Pfizer. Pfizer announced in May 2016 that it opposed the use of its products in executions, stating, “Pfizer makes its products to enhance and save the lives of the patients we serve. Consistent with these values, Pfizer strongly objects to the use of its products as lethal injections for capital punishment.”

While state secrecy practices leave it unclear from whom Arkansas obtained the restricted drug, Rachel Hooper, a spokesperson for Pfizer, said, “We have implemented a comprehensive strategy and enhanced restricted distribution protocols for a select group of products to help combat their unauthorized use for capital punishment. Pfizer is currently communicating with states to remind them of our policy.”

As pharmaceutical companies have made their drugs more difficult for states to use, prisons have turned to alternate sources. The Alabama Department of Corrections contacted about 30 compounding pharmacies in an effort to obtain lethal injection drugs, but all refused.

Compounding pharmacist Donnie Calhoun said, “For me, as a healthcare professional, I want to help people live longer. The last thing I want to do is help someone die.” A Virginia pharmacist who was contacted by the attorney general’s office also refused, saying, “No one will do it.”

Virginia recently adopted a lethal injection secrecy statute that would conceal the identity of its drug supplier, joining many other death penalty states in shielding key information about executions from public scrutiny.