cosurfactant

co- +‎ surfactant

cosurfactant (plural cosurfactants)

1. A surfactant acting in tandem with another surfactant to enhance its properties.
   • 2015 June 23, In-hwan Baek et al., “Design of a gelatin microparticle-containing self-microemulsifying formulation for enhanced oral bioavailability of dutasteride”, in Drug Design, Development and Therapy‎, volume 9, →DOI:

     In general, when SMFs consisting of oil, surfactant, and/or cosurfactant (cosolvent) are placed in an in vitro dissolution medium or in gastrointestinal fluid in vivo, homogeneous oil-in-water microemulsions form spontaneously with mild agitation.