Compositions comprising (a) pharmaceutically acceptable thiol groups containing compound(s) to inhibit efflux pumps in a concentration of 0.5% - 95%, wherein the thiol groups containing compound(s) is (are) selected from: - thiol group containing compounds having a molecular weight of at least 250 g/mol, - thiol group containing compounds having at least 10 thiol groups per molecule, and - thiol group containing compounds being selected from thiolated carbomer, thiolated poly(meth)acrylic acid, thiolated cellulose, thiolated polyglucosamines, thiolated polylysines, thiolated polyarginines or glutathione, (b) drug(s) of limited absorption due to efflux pumps in a concentration of 0.1% - 90%, if thiol groups containing compound(s) is(are) missing and (c) optionally further auxiliary agents in a concentration of 0.5% - 80%.
