Polyaminopropyl biguanie (PAPB), also polyhexamethylene biguanide (PHMB), polyhexamethylene guanide or polyhexanide, is a disinfectant and a preservative used for disinfection on skin and in cleaning solutions for contact lenses. It is a polymer or oligomer where biguanide functional groups are connected by hexyl hydrocarbon chains, with varying chain lengths. PAPB is specifically bactericidal at very low concentrations (10 mg/l) and is also fungicidal.