(Adds dropped letter "a" to spelling of midazolam in paragraphs four, 13 and 17)
By Jim Forsyth
SAN ANTONIO, Texas, Oct 2 (Reuters) - Three Texas death row inmates claim the state plans to execute them by experimenting with new drugs, never used for such a purpose, that were obtained under false pretenses, attorneys told Reuters on Wednesday.
Texas is turning to the new execution drugs in a desperate attempt to keep the United States' most active execution chamber operating despite dwindling supplies of the drug traditionally used for lethal injections, a lawsuit filed by the inmates says.
The inmates, one of whom is scheduled for execution on Oct. 9, allege the Texas Department of Criminal Justice used the address of a hospital unit shuttered three decades ago in order to obtain the three new drugs.
They say the drugs - propofol, midazolam and hydromorphone - would likely not have been supplied if the manufacturers knew the purpose they would be used for, according to a lawsuit filed this Tuesday in federal court in Houston.
Texas prison officials declined to comment on the allegations made in the lawsuit.
They said Wednesday that they have enough pentobarbital, the barbiturate used in Texas executions since 2012, to last them until at least next year. The state recently received a fresh supply of the drug from a Texas compounding pharmacy, after warning in August that their supplies were nearly exhausted.
"The purchase will allow the agency to carry out all currently scheduled executions," state officials said in a statement.
Texas has seven executions scheduled, including two in October. The state has executed 13 inmates so far this year.
Among the inmates suing the state is Michael Yowell, set to die Oct. 9 for killing his parents and blowing up their home in Lubbock, Texas, in 1998.
The lawsuit alleges that because of a shortage of drugs traditionally used in executions, Texas correction officials are turning to "drugs and methods of execution that have never been used before, by any state. Some are banned for use in animal euthanasia," and run a "substantial risk of grave pain," the suit claims.
"We are concerned that they are experimenting on people," Austin attorney Maurie Levin, one of the lawyers representing the inmates, told Reuters on Wednesday.
The lawsuit says Texas is trying to hide from the public its plans to use new drugs for executions. It asks the court to halt executions in Texas until the state can review the drugs.
Propofol and midazolam are used as sedatives in medical procedures. Hydromorphone is used to relieve pain.
Texas, which has carried out more executions than any other state since the death penalty was reinstated in 1976, switched to administering a single, lethal dose of pentobarbital last year when the state had to change drugs after the maker of sodium thiopental, Hospira Inc, stopped manufacturing it.
Pentobarbital is used for physician-assisted suicide in Europe. Denmark's Lundbeck LLC, which makes pentobarbital, has objected to its use in executions, leaving it in short supply.
Several states have reported running low on pentobarbital and have halted executions while they seek access or resolve other lethal injection issues, said Richard Dieter, executive director of the Death Penalty Information Center.
The Texas lawsuit claims the state used a subterfuge to obtain propofol, midazolam and hydromorphone from manufacturers unwilling to have their products used for execution.
The state purchased the drugs for delivery to the "Huntsville Unit Hospital," a medical ward that has not existed since 1983, to cover up the fact that the drugs may be used for executions, the lawsuit alleges.
It also says the state attempted to purchase a pentobarbital compound from New York-based Pharmacy Innovations delivered to the same address with a prescription written in the name of the prison warden. The suit says the company canceled the order when it found out who was ordering it and what it was for.
The case is 4:13-cv-02901 in the U.S. District Court for the Southern District of Texas Houston Division. (Editing by Karen Brooks, Carey Gillam and Andrew Hay)