On the second day of a trial that seeks to have Tennessee's lethal injection protocols declared unconstitutional, testimony has centered on the role of compounding pharmacists in producing lethal injection drugs.

Tennessee's protocol calls for the use of compounded pentobarbital. That's because the only commercial producer of the drug has placed restrictions on its distribution to prevent it from being used in executions.

Dr. James Ruble is a professor with the University of Utah College of Pharmacy. He testified on Wednesday that Tennessee's protocol lacks the safeguards needed to prevent problems with the compounded drug that could cause extreme pain.

Meanwhile, attorneys for the state tried to show that the Tennessee Board of Pharmacy regulations are sufficient to guard against such problems.

Thirty-three death row inmates are suing the state over lethal injection.