An Oklahoma pharmacy has refused to provide the state of Missouri with drugs for a planned Feb. 26 execution by lethal injection. But state officials have said the sentence will be carried out anyway.

According to court documents filed on Monday, The Apothecary Shoppe, a compounding pharmacy in Tulsa, Okla., says it will not provide Missouri Department of Corrections with pentobarbital, the drug the state uses to carry out lethal injections on death row inmates.

The decision to withhold the drugs came after lawyers for Michael Taylor, a condemned inmate convicted of kidnapping, raping and murdering a 15-year-old Kansas City girl in 1989, filed a lawsuit against the pharmacy in an attempt to halt his upcoming execution. Taylor’s lawyers argue that the drug could cause unnecessary pain because it comes from an unregulated compounded pharmacy.

(MORE: Missouri Executes Man After Appeals Fail)

States around the country have struggled to administer lethal injections since pharmaceutical companies have begun denying execution drugs to prison systems, forcing many of them to turn to compounding pharmacies, which are not under federal oversight.

A federal judge temporarily halted the Oklahoma pharmacy from providing pentobarbital to the corrections department last week. When asked how that temporary stay would affect the upcoming execution, David Owen, communications director for the Missouri Department of Corrections, said Taylor’s execution would go forward regardless.

“The Missouri Department of Corrections is prepared to carry out the execution of Michael Taylor on Feb. 26 pursuant to the warrant issued by the Missouri Supreme Court,” Owen said to TIME in an e-mail on Friday.

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