Polyquaternium-1 (PQ)

Polyquaternium-1 (Polyquad) is a synthetic polymeric quaternary ammonium preservative widely used in ophthalmic solutions, including artificial tears, contact lens disinfectants, and some antiglaucoma formulations. It was developed as a less cytotoxic alternative to benzalkonium chloride, due to its larger size and hydrophilic nature, which limit penetration into mammalian cells. Polyquad exhibits effective antimicrobial activity, especially against bacteria and fungi, by disrupting their membranes. Although generally well tolerated and less toxic to the ocular surface compared to older preservatives, some in vitro and clinical studies report mild cytotoxic effects on ocular cells, particularly with frequent or prolonged use. Polyquad is not a therapeutic target but rather a pharmaceutical excipient; it does not act as or interact with biological macromolecules in a manner typical of pharmacological targets[1][3][5][6][7][8].

Other names

PolyquadPolidronium chloridePQPolyquat 1OnaMer MOnyxsperse 12SPolyquaternium I

Not applicable as a drug target; acts as a preservative by disrupting microbial cell membranes