A comparison of two formulations for etomidate, 2-hydroxypropyl-beta-cyclodextrin (HPCD) and propylene glycol

The unphysiologic osmolality of commercial preparations of etomidate dissolved in propylene glycol has limited its use as a drug to induce anesthesia. We wanted to determine whether hydroxypropyl-beta-cyclodextrin (HPCD) is a more suitable solvent than propylene glycol by comparing pharmacokinetics, pharmacodynamics, and side effects of etomidate preparations in each solvent. Twenty-four healthy, male volunteers, randomly assigned to either the male volunteers, randomly assigned to either the HPCD or the propylene glycol group received etomidate, 0.3 mg/kg, dissolved in one of the two test solvents. We recorded arterial blood pressure, heart rate, electrocardiogram, electroencephalogram, pain on injection, myoclonic movements, and venous sequelae. Systolic and diastolic blood pressure and heart rate were similar in both groups. Frequency and severity of pain on injection differed significantly between groups. In the propylene glycol group, five subjects suffered venous sequelae: in three, thrombophlebitis resolved after 5 days; in one, after 10 days; and in the other, after 12 days. In the HPCD group, only one subject suffered severe pain on injection and none had venous sequelae. We conclude that HPCD may be superior to propylene glycol as a solvent for etomidate. HPCD is associated with less pain, less thrombophlebitis, and no hemolysis without clinically important alteration of pharmacokinetics or pharmacodynamics of etomidate.