As a debate rages over plans by the US state of Arkansas to execute eight death row inmates before its supply of lethal drugs expires at the end of April, the international pharmaceutical industry is again in the spotlight, where it doesn’t want to be.

In the crosshairs this time are midazolam, a powerful sedative intended to leave a prisoner unable to feel pain; vercuronium bromide, a medication that prevents muscle movement; and potassium chloride, which stops the heart. Arkansas has obtained supplies of all three, but they are only able to be used in lethal injection “cocktails” up to the end of this month.

Again, Pfizer is at the center of attention – this time through its distributor McKesson – along with drugmakers Fresenius Kabi USA and West-Ward Pharmaceuticals, a subsidiary of London-based Hikma. All three have tried in the past to keep their drugs out of the Arkansas prison system’s hands. McKesson earlier this month was able to obtain a temporary restraining order mandating that the state return its supplies of vercuronium bromide, made by Pfizer.

The pharmaceuticals giant said it had twice requested that Arkansas return any of the drugs that stem either from its own portfolio or that of its subsidiary Hospira, regarded as world’s largest manufacturer of injectable drugs. Pfizer blamed McKesson for this month’s slip-up with vercuronium bromide, saying the distributor had violated its contract by selling the restricted muscle relaxant to the state prison system. McKesson said it had been misled by authorities, who claimed it would be used for “medical purposes.

Fresenius Kabi USA and West-Ward told the newspaper New York Times they had asked the state to refrain from using their potassium chloride and midazolam drugs for executions. The latter drug has been eyed critically since it played a role in a botched execution in Arizona in 2014. A US Surgeon recently testified in federal court that midazolam is not suitable for executions.

The EU, which bans the death penalty also bans exports of drugs for use in lethal injections; it has called on Arkansas to halt the executions. Some US states have restrictions, but whether not medications can be used to carry out the death penalty is often up to the manufacturer.

Several years ago, in view of rising opposition to the death penalty, US drugmakers began to include clauses in distribution contracts barring the use of their medications in executions. This has meanwhile led to shortages. In some cases, legal delays have led prisons’ stockpiles to expire before scheduled executions, and corrections authorities have turned to compounders or South American sources. Some states have resorted to dubious means to obtain drugs, sometimes using medicines not widely seen as suitable.

Several US death penalty states meanwhile have passed legislation allowing suppliers of execution drug to remain anonymous. The US Food and Drug Administration, FDA, also has been pulled into the fray.  In January, the state of Texas filed a lawsuit against the regulatory agency, demanding it release an impounded shipment of the barbiturate sodium thiopental to the state prison system.

While Arkansas’ Republican governor has insisted that it is “in the interest of justice” to carry out as many executions as possible before drug inventories expire, several federal courts have struck down parts of the state’s plans for completing eight executions this month – the quota will not be reached.