The antibiofilm activity of SSAs was established for 1 -5 against homogenous and heterogeneous biofilms containing C. albicans (SC5314) and/or P. aeruginosa (PAO1). For all biofilms, near complete inhibition of biofilm formation was observed for at least one condition tested, with 1, 2 and 3 retained as lead antibiofilm SSAs. These SSAs were subsequently supplied as a 1:1 co-formulation to the biofilms, resulting in enhanced biofilm inhibition compared to the individual SSAs against C. albicans (SC5314), and to enhance the activity of 3 against heterogenous C. albicans (SC5314) and P. aeruginosa (PAO1) biofilm formation. Previous data had already led us to hypothesise that the SSA mechanism of antimicrobial activity included selective adhesion to, and subsequent permeation through the cellular membranes. However, we now confirm this also for C. albicans (SC5314), where 3 is shown to preferentially target the (pseudo) hyphae. With this hypothesised mechanism of action, we believe that these data show that through co-formulation, we can modify SSA membrane adhesion and permeation properties selectively and as a result increase antibiofilm activity against target biofilms of interest. Finally, we performed a range of DMPK studies with 5, that show that the substitution of the (thio)urea functionality with the squaramide does not vastly impact the in vitro drug-like properties of the SSAs, however does impact the intravenous in vivo profile as observed with an increase in clearance and volume of distribution.