We investigate scaling rules for the ionization cross sections of multicharged ions on molecules of biological interest. The cross sections are obtained using a methodology presented in [Mendez et al. J. Phys B (2020)], which considers distorted-wave calculations for atomic targets combined with a molecular stoichiometric model. We examine ions with nuclear charges Z from +1 to +8 impacting on five nucleobases -adenine, cytosine, guanine, thymine, uracil-, tetrahydrofuran, pyrimidine, and water. We investigate scaling rules of the ionization cross section with the ion charge and the number of active electrons per molecule. Combining these two features, we define a scaling law for any ion and molecular target, which is valid in the intermediate to high energy range, i.e., 0.2-5 MeV/amu for oxygen impact. Thus, the forty ion-molecule systems analyzed here can be merged into a single band. We confirm the generality of our independent scaling law with several collisional systems.