TY - CHAP M1 - Book, Section TI - Barbiturates A1 - Burnett, Michelle A2 - Freeman, Brian S. A2 - Berger, Jeffrey S. PY - 2014 T2 - Anesthesiology Core Review: Part One Basic Exam AB - Barbiturates are derivatives of barbituric acid. The presence of oxygen in the pyrimidine nucleus at carbon 2 position makes the drug an oxybarbiturate (eg, methohexital). In contrast, thiobarbiturates (eg, thiopental) have a sulfur atom at the carbon 2 position. Substitutions at carbon 5 position with either aryl or alkyl groups produce hypnotic and sedative effects. Phenyl groups enable the potent anticonvulsant activity. Thiamylal and thiopental, both thiobarbiturates, have similar pharmacological profiles and are available as racemic mixtures. Methohexital is marketed as a racemic mixture of two alpha isomers. The beta-1 stereoisomer form of methohexital produces excessive motor responses. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/19 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=1102567022 ER -