Delivery of peptides inside specific compartment of cells is a promising strategy to inhibit a large number of therapeutic targets. Examples include anticancer therapeutics able to inhibit cytosolic protein-protein interactions (PPIs) involved in tumor development. P53 inhibitors, MDM2 and MDMX obtained lots of attention as potential target due to their role in different cancers including forms of sarcoma, breast and skin cancer. In healthy cells, MDM2 and MDMX inhibit and regulate the activity of the tumor suppressor p53, but in some cancers, these inhibitors are overexpressed and inactivate p53. We have developed peptides that conjugate designed cyclic cell-penetrating peptides with highly potent stapled peptide dual inhibitor. We investigated the ability to bind to lipid membranes, the mechanism of internalisation and localisation inside the cells. Our results show that despite having picomolar affinity for both MDM2 and MDMX, the conjugates did not kill the cells through reactivation of the p53 pathway. It, however provides valuable information on the potential and limitation of the conjugation strategy. These results will guide rational design to improve this strategy, decrease its unwanted toxicity to healthy cells and improve its intracellular activity.