Propylene glycol (1,2-propanediol) is an organic compound (a diol alcohol), usually a tasteless, odorless, and colorless clear oily liquid that is hygroscopic and miscible with water, acetone, and chloroform. It is manufactured by the hydration of propylene oxide. Propylene glycol is used as a solvent for intravenous, oral, and topical pharmaceutical preparations It is generally considered safe. However in large doses it can be toxic, especially if given over a short period of time. Intravenous lorazepam contains the largest amount of propylene glycol of commonly used drugs. In adults with normal liver and kidney function, the terminal half-life of propylene glycol ranges from 1.4 to 3.3 hours. Propylene glycol is metabolized by the liver to form lactate, acetate, and pyruvate. The nonmetabolized drug is excreted in the urine mainly as the glucuronide conjugate, approximately 12 to 45 percent is excreted unchanged in urine. Renal clearance decreases as the dose administered increases (
Solubility greater than or equal to 100 mg/mL at 70 °F (NTP, 1992)
Formula
C3H8O2
Mol. Weight
76.09
CAS #
57-55-6
Form
Powder
State
Thick odorless colorless liquid. Mixes with water. (USCG, 1999)
See origin →
Functions
Humectant
A moisture magnet. Pulls water from the air and deeper skin layers up to the surface to keep skin plump and hydrated.
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Solvent
Dissolves other ingredients so they distribute evenly in the formula. Often the invisible "base" everything else is mixed into.
Viscosity Controlling
Locks In Moisture
Traditional Use
Developed in the 1930s as a synthetic glycol compound. Became widespread in cosmetics after World War II as a humectant and solvent; replaced animal-derived glycerin in many formulations due to better stability and lower cost.