  The scaling function $f(\psi')$ for medium and heavy nuclei with $Z\neq N$
for which the proton and neutron densities are not similar is constructed
within the coherent density fluctuation model (CDFM) as a sum of the proton and
neutron scaling functions. The latter are calculated in the cases of $^{62}$Ni,
$^{82}$Kr, $^{118}$Sn, and $^{197}$Au nuclei on the basis of the corresponding
proton and neutron density distributions which are obtained in deformed
self-consistent mean-field Skyrme HF+BCS method. The results are in a
reasonable agreement with the empirical data from the inclusive electron
scattering from nuclei showing superscaling for negative values of $\psi'$,
including those smaller than -1. This is an improvement over the relativistic
Fermi gas (RFG) model predictions where $f(\psi')$ becomes abruptly zero for
$\psi'\leq -1$. It is also an improvement over the CDFM calculations made in
the past for nuclei with $Z\neq N$ assuming that the neutron density is equal
to the proton one and using only the phenomenological charge density.
