Several human rights and anti-death penalty groups have asked the American Pharmacists Association to prohibit members from participating in executions, a request that comes as states increasingly turn to pharmacists for lethal injection drugs.

The groups, which include Amnesty International, the NAACP and the American Civil Liberties Union, are targeting drugs made by compounding pharmacies. Such drugs, which are not federally regulated, are individually mixed versions of medications that prison systems are finding increasingly difficult to obtain.

Death penalty opponents say such drugs put inmates at risk of pain and suffering. Two years ago, an outbreak of meningitis that killed 64 and sickened hundreds was traced to a compounding facility in Massachusetts.

Pharmacists who provide compounded drugs are violating key provisions of the pharmacists' association code of ethics, including helping patients achieve "optimum benefit" from their medications, according to a letter the death penalty opponents presented to the association on Monday.

"Participation in executions undermines the position of trust that pharmacists enjoy in this nation," said the letter sent ahead of the association's annual meeting beginning Friday in Orlando, Fla. The letter is part of a lobbying effort spearheaded by the nonprofit group SumOfUs, which says it represents consumers and workers and seeks to "counterbalance the growing power of large corporations."

Numerous drug makers have put their products off limits for executions, drying up the supply available to prison systems. Missouri has used a compounded version of pentobarbital to execute four inmates with plans for a fifth at midnight Wednesday. Texas has used compounded pentobarbital to execute six inmates, with a seventh execution planned for Thursday.

Lawyers for death row inmates in Oklahoma have alleged the state used compounded pentobarbital to put an inmate to death in January. Michael Wilson's final words were, "I feel my whole body burning," and then he didn't move.

A plan by Georgia to use a similar specialty batch of pentobarbital has been put on hold by a lawsuit challenging the state prison agency's refusal to identify the compounding pharmacy that provided the drug. The lawsuit also questions the drug's safety and effectiveness.

In Ohio, the state's policy calls for the prison system to obtain compounded pentobarbital as a first choice, and then to use a backup method of a sedative and painkiller if the compounded drug can't be found. The state has chosen the backup method in the past two scheduled executions, although only one was carried out.

The pharmacists' association is unlikely to adopt any statement at this year's meeting because it has a long process for developing policies, spokeswoman Michelle Spinnler said in an email to The Associated Press Tuesday. She said the earliest the group's delegates could consider any proposal would be next year.

The association previously adopted policies opposing the use of the word "drug" for chemicals used in lethal injections, and opposing laws or regulations that require or prohibit pharmacists from participating in lethal injections.

Amnesty International believes the call to the pharmacists is another chance to express opposition to capital punishment, said Thenjiwe McHarris.

"Their profession is mean to preserve life, it's meant to do no harm, and the death penalty doesn't just challenge that, it's completely opposite to that mission," she said.

Any pharmacists' association policy would not affect members' ability to practice. But death penalty opponents hope that a policy change would filter down to state regulatory boards, which could require such a ban as part of licensing.