Methohexital (C14H18N2O3) was a sedative barbiturate substance which was primarily used in hospitals and other medical facilities. It was often used in tandem with anesthesia to induce a deep sedation.
The box of methohexital seen in "Carpenter Street" was mistakenly labeled "mexhohexital". However, the name was spelt correctly in the episode's final draft script. The same teleplay also indicated that a drug Loomis is shown injecting into Georgia Tandy's left arm, after sedating her with a chloroform-covered rag, was intended to be methohexital.