Polysorbate 80 — Frequently Asked Questions

Its fatty chain is oleic acid, an eighteen-carbon monounsaturated chain, considerably longer than the twelve-carbon lauric chain of Polysorbate 20. A longer chain gives each micelle a larger and more lipophilic interior, so it can accommodate bigger and more oil-loving molecules. Vegetable oils, vitamin E and fat-soluble actives that leave a Polysorbate 20 system hazy will often go clear with Polysorbate 80.

It is used to solubilise poorly water-soluble drug substances and, importantly, to stabilise proteins. Protein molecules tend to unfold and aggregate at air-liquid and container interfaces during manufacture, shipping and freeze-thaw. Polysorbate 80 occupies those interfaces preferentially and keeps the protein away from them, which is why it appears at low concentration in many biologic and vaccine formulations.

It can. The oleic chain carries a double bond, which is a site for oxidation, and oxidation produces peroxides and fatty acid fragments that can degrade sensitive actives. Peroxide value is therefore a meaningful specification point for pharmaceutical grades, and the material should be stored sealed, cool and away from light. The fully saturated Polysorbate 20 and 60 do not have this vulnerability.

Yes. Tween is a long-established trade name for the polysorbate series, so Tween 80 and Polysorbate 80 refer to the same material. Polysorbate 80 is the INCI and pharmacopoeial name and is the designation used on ingredient declarations. Grade still matters, since pharmaceutical grades are controlled on peroxide value, metals and related substances well beyond cosmetic requirements.