Propofol is an insoluble drug that requires a lipid vehicle for emulsification. The standard propofol emulsion formulation contains 10% soya oil as the oil phase and egg lecithin as the emulsifying agent that is composed of long-chain triglycerides.
This formulation supports bacterial growth new formulations contain preservatives with bactericidal action, such as propofol with EDTA (ethylene diamine tetraacetic acid) or metabisulfite.
A new emulsion of 1% Propofol emulsion (Ampofol) containing 50% (5% soybean oil and 0.6% egg lecithin) less lipid has recently become available which possesses no significant differences and is equipotent to Diprivan with respect to onset times, dosage requirements, Bispectral Index values, haemodynamic variables, recovery times, or patient satisfaction scores but is associated with a higher incidence of pain on injection.
An emulsion containing long and medium-chain triglycerides, propofol lipuro reduces the incidence of pain on injection and also shows to prevent the rise of plasma triglyceride concentrations.
A nonlipid, modified cyclodextrin-based formulation of propofol; sulfobutyl ether-beta-cyclodextrin, captisol has been developed.
Cyclodextrins, apart from captisol are ring sugar molecules which form guest—host complexes. The guest compound (propofol) migrates between the hydrophilic centre of the cyclodextrin molecule and the water-soluble phase.
This allows propofol to be sparingly soluble in water and to be presented in an injectable format. After injection, the guest (propofol) migrates out of the cyclodextrin into the blood.
Egan et al found no significant differences in the pharmacokinetics or pharmacodynamics with the conventional propofol in lipid emulsion.