Density functional theory (DFT), quantum theory of atom in molecule (QTAIM), and natural bond orbital (NBO) have been performed for geometry optimization, binding energy, electronic properties, and adsorption of drug isoniazid (INH) on the pristine and Al-doped Mg12O12 nanocage (MgONC). This drug has tendency to attach via its nitrogen and oxygen atoms to the Mg atoms of the nanocage with adsorption energy in range of -0.96 to - 2.58 eV based on the dispersion corrected M062X level of theory. Isoniazid was found to be properly adsorbed on the MgONC while the electronic properties of the MgONC was not significantly changed. But, Al-doped MgONC presents high sensitivity to isoniazid, compared with the pristine nanocage structure, particularly the Al doped one was changed dramatically. The Al-doped MgONC can adsorb isoniazid more strongly with adsorption energy (E-ads) equal to - 2.58 eV, corresponding to the stable configurations. The QTAIM analysis was investigated for both type's of structural aspects and electronic properties associated with adsorption processes on the MgO nanocage. Furthermore, NBO analysis indicated a stronger donor-acceptor interactions with INH drug and MgONC. Our calculations showed that the HOMO/LUMO gap of the Al-doped MgONC is significantly changed after the adsorption of INH molecule corresponding to the most stable configuration that gives rise enhance the electrical conductivity of the MgONC. In conclusion, the electronic properties of Al-doped MgONC are strongly sensitive to the presence of INH molecule and therefore it can be used in (bio) sensor devices and can be used to trace the drug via spectrophotometric techniques in the body.