Pharmacokinetics of propylene glycol in humans during multiple dosing regimens.

The pharmacokinetics of propylene glycol has been examined during multiple oral-dosing regimens. The glycol is rapidly absorbed, with Cpmax observed within 1 h following administration. The terminal elimination half-life is approximately 4 h. After a minimum of 10 half-lives of maintenance dosing on a fixed regimen, the accumulation of propylene glycol differed significantly among individuals because of variability in apparent clearance. The average apparent total body clearance is approximately 0.1 L/kg X h and may be concentration dependent. The apparent volume of distribution is approximately 0.5 L/kg, approximating total body water.