Louisiana has been ordered to delay for 90 days the execution of a convicted killer that had been planned with a mix of the same two drugs that left a condemned Ohio inmate gasping and convulsing as he was put to death.

Christopher Sepulvado had been scheduled to die on Wednesday at a Louisiana prison using a combination of the sedative midazolam and pain killer hydromorphone if the regularly listed drug pentobarbital was unavailable.

U.S. District Court Judge James Brady ordered the execution delayed at least until May 4 and set a trial to begin April 7 on a defense challenge to the constitutionality of the state's execution methods.

"The stay will allow additional time for review and responses to outstanding issues related to the execution," Louisiana's corrections department said in a statement.

Lawyers for Sepulvado had argued they could not prepare an adequate appeal if Louisiana did not disclose what drugs it planned to use for the execution or determine whether he would face pain and suffering in violation of the U.S. Constitution's protection against cruel and unusual punishment.

Sepulvado was convicted in 1993 of killing his 6-year-old stepson and sentenced to death.

Louisiana and other states have been increasingly forced to look for alternate sources of execution drugs as pharmaceutical companies raise objections to their products being used for capital punishment.

Some states have turned to compounding pharmacies, which produce small amounts of drugs by prescription and are not regulated by the U.S. Food and Drug Administration, prompting defense attorneys to question the quality of the drugs and whether they could cause undue pain during an execution.

Ohio turned to a combination of midazolam and hydromorphone never before used in an execution in the United States to put Dennis McGuire to death in January. Media witnesses said at the time he appeared to struggle for breath during the execution.