Limits on the use of propylene glycol in topical preparations

: The authors define some limits for useful concentrations of propylene glycol (P.G.) by determination of inhibition produced in cell respiration from (crushed) mouse liver and in human cutaneous fibroblastic proliferation. They conclude that P.G. is able to inhibit both these physicological mechanisms from concentration as weak as 5.5% and 2% respectively. They give a method for analytical determination of P.G. in cosmetic and pharmaceutical products using gas liquid chromatography. This method is useful for a wide range of concentrations.