Missouri has executed a man convicted of killing a jewellery store owner during a 1991 robbery after the US supreme court denied last-minute appeals that in part challenged the drug used in the execution.

“After the United States supreme court vacated three separate stays of execution on January 29 2014, Herbert Smulls was executed for the 1991 murder of Stephen Honickman,” said Chris Koster, the Missouri attorney general.

Smulls, 56, was pronounced dead at 10.20pm local time at a state prison in Bonne Terre after receiving a lethal dose of pentobarbital, the corrections department said.

The supreme court on Wednesday lifted a temporary stay of execution for Smulls, denying last-minute appeals. The top court late on Wednesday also vacated a stay from the US court of appeals.

Lawyers for Smulls sought another stay late on Wednesday but Missouri went ahead with the execution before the midnight expiration of the state’s death warrant.

Lawyers for Smulls had sought to block his execution on multiple grounds, arguing in part that the compounded pentobarbital drug Missouri used to kill him may not be as pure and as potent as it should be, which could cause undue suffering.

Missouri and several other states have turned to compounding pharmacies, which are not regulated by the US Food and Drug Administration, to acquire drugs for executions after an increasing number of pharmaceutical manufacturers objected to their drugs being used in capital punishment.

The increasing use of compounded drugs and untested drug mixes has brought renewed debate over the death penalty in the United States. In Oklahoma an inmate said he felt burning through his body when the lethal drugs were injected during an execution in early January. Later in the month an Ohio man gasped and convulsed during his execution with a two-drug mix never before used in the United States.

Smulls was the sixth person executed in the United States in 2014 and the third in Missouri since November.