Missouri is due to execute a multiple murderer just after midnight in which the state will for the first time use a lethal dose of pentobarbital obtained from a secret compounding pharmacy.

Barring last minute intervention by the courts, at 12.01am on Wednesday Joseph Paul Franklin, 63, will die for a spate of seven murders of black and Jewish people carried out between 1977 and 1980. He is suspected in as many as 20. Though there are no doubts about Franklin’s guilt, or the heinousness of the racist killings in which he engaged, the procedure is controversial by dint of its protocol.

In order to keep the identity of the pharmacy that has supplied the drugs a secret, the Missouri corrections department has listed the company as a member of its “execution team”, thereby extending to it the right to anonymity. States across the US are becoming increasingly secretive in their methods of execution as a means of circumventing a stringent boycott on medical drugs used in lethal injections. The boycott, led by the European Union, has drastically staunched the flow of medicines to the extent that some states have been forced to delay scheduled executions.

Franklin’s lawyers have protested that the use of pentobarbital obtained from a secret supplier could cause him an “excruciatingly painful execution”. In court documents, they say that “compounded drugs are all but unregulated, and their ingredients come from an unsavoury network of ‘grey market’ suppliers whose unknown products subject the end-user to severe risks.”

A pharmacy expert, Dr Larry Sasich, provided the Missouri courts with an affidavit in which he cast compounding pharmacies as “an emerging, substandard drug industry responsible for making large quantities of unregulated, unpredictable and potentially unsafe drugs”.

Missouri’s dependency on compounded pentobarbital is just one example of the extreme measures that states are taking in the face of the boycott of sales of medical drugs to corrections departments that is increasingly starting to bite. The EU-led boycott has spread to individual pharmaceutical companies that are now widely refusing to distribute to US prisons, angry that their products, designed to enhance and prolong life, are being used to kill people.

Other states that have turned to compounding pharmacies include Texas, the most active of all the death penalty states, and South Dakota. Georgia has passed a new law that is now being challenged in the courts that declares the identity of the compounding pharmacy supplying pentobarbital to be a “state secret”.

Other states have begun turning to medical drugs that have never before been used in executions, in the hope of bypassing the boycott. In the past 10 days Florida has executed two prisoners using a three-drug cocktail that includes for the first time the sedative midazolam hydrochloride. An Associated Press reporter present at one of the executions, that of the convicted murderer William Happ, said he “remained conscious longer and made more body movements after losing consciousness than other people executed recently by lethal injection under the old formula”.

Last week Ohio was poised to use midazolam for the first time in a two-drug cocktail in the execution of child-killer Ronald Phillips, but the procedure was delayed for unrelated reasons.

On Tuesday the US Senate passed new legislation that would increase federal regulation by the Food and Drug Administration over some compounding pharmacies. The measure was designed to meet some of the criticisms levelled at the sector after the meningitis outbreak last year that killed 64 people and was traced back to a compounding pharmacy in Massachusetts.

However, the new bill is unlikely to have any impact on the practice of the death penalty. The compounding pharmacies now used by Georgia, Missouri, South Dakota, Texas and several other states tend to be small businesses that concoct one-off orders of drugs for personal use, while the new legislation specifically only covers outlets that are mass-producing versions of major medicines.

In future, the compounding pharmacies employed to knock up batches of sedatives for use in executions are likely to remain totally unregulated by the federal authorities. The only scrutiny to which they are subjected comes from local state services that tend to be more patchy.