PEGylation of Propofol Reduces Its Adsorption to Extracorporeal Membrane Oxygenator (ECMO) Components

Extracorporeal membrane oxygenation (ECMO) is a life-saving cardiopulmonary bypass technology for critically ill patients. Patients treated with ECMO receive multiple drugs to treat critical illnesses, prevent infections, and maintain sedation. However, inaccurate dosing information of some of the administered drugs is a significant cause of ECMO related mortality. Hydrophobic drugs tend to adsorb on the surface of ECMO circuit components leading to suboptimal dosing and therapeutic failure. Modifying the drugs can be exploited as a strategy to reduce drug adsorption in ECMO circuits. Propofol (Diprivan®) is a widely used anesthetic in ECMO patients that is known to substantially adsorb to ECMO circuit components due to its hydrophobicity. The objective of this work was to evaluate the PEGylation of propofol as a strategy to reduce its adsorption to the ECMO circuit. Poly(ethylene glycol) (PEG) was covalently conjugated to propofol with varying PEG lengths, i.e., 3 monomers of PEG (PEG₃), 5 monomers of PEG (PEG₅) and 2 kDa molecular weight PEG (PEG_2kDa). The conjugates were synthesized, characterized, and compared for their water solubility, ability to spontaneously form micelles, and in reducing adsorption to hydrophobic materials in an in vitro ECMO mimic assay. Further, the conjugates were tested for their anesthetic activity in a C57BL/6 mouse model. We demonstrated that PEG₅-Propofol and PEG_2kDa-Propofol had improved water solubility and significantly reduced the adsorption of propofol. PEG₅-Propofol also demonstrated a similar anesthetic activity (520 ± 109 secs) to free propofol (485 ± 103 secs). Our results demonstrate that PEG₅-Propofol is a promising anesthetic for administration to patients on ECMO.