This work explored the interaction of two different drugs, cetirizine (CTZ) and tetrahydrozoline (THZ) with two different cucurbit[n]urils CB[n], cucurbit[6]uril (CB[6]) and cucuribit[7]uril (CB[7]). Two binary inclusion complexes were investigated in solution and in the solid-state, by lyophilization and by the formation of physical mixtures. In most of the cases 1:1 complex was obtained, for both studied drug. 1HNMR and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry were used to study the complexes prepared in solution. The lyophilized solid complexes were characterized by Fourier transform-infrared spectroscopy (FT-IR), powder X-ray diffractometry (PXRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). MALDI-TOF, FT-IR and PXRD experimental results established in this work reveal the presence of the non-covalent interaction between the selected drugs and the two hosts. The TGA and DSC confirmed the enhancement of the thermal stability of each drug and the production of a thermally stable solid complex. The 1HNMR has shown that the guests’ protons faced shifting in ppm and broadening of peaks upon the formation of inclusion complexes with the selected CB[n]s. Among all prepared complexes, CTZ@CB[6] is the only complex where most of its aliphatic protons remain unchanged in the presence of CB[6] which suggest the formation of a weak complex or an external complex. The diffusion coefficients (D), obtained from the diffusion-controlled NMR Spectroscopy (DOSY) measurements, for the complexation of the selected drugs with CB[6] and CB[7], were decreased in presence of hosts compared to the free guests indicating formation of guest-host adduct. The density functional theory (DFT) calculations confirmed the formation of a weak complex between CTZ and CB[6] while favorable complexes of CTZ@CB[7] and THZ@CB[6,7]. The results presented in this thesis show that CTZ form a stable inclusion complex CB[7] and THZ form stable complex with the two hosts through non-covalent interactions such as van der Walls interactions, hydrogen bonding, and ion-dipole interactions resulting in enhanced chemical stability of these pharmaceutical compounds. This study generates initial data for potential drug delivery systems for these selected pharmaceutical compounds by CB[n].