This thesis presents the design and evaluation of dual-purpose small molecules for the modulation and detection of the calcium-sensing receptor (CaSR), a critical regulator of calcium homeostasis implicated in diseases such as fibrosis, cancer, and chronic kidney disease. A series of TNCA-derived analogs were synthesized and tested for their ability to activate CaSR in cellular models. The study employs cell-based fluorimetry, IP-One signaling assays, and molecular docking simulations to characterize ligand-receptor interactions and optimize candidates for theragnostic applications. Notably, fluorinated analogs suitable for 18F PET imaging retained high affinity and specificity for CaSR. Multidrug synergy analysis revealed that combining TNCA analogs with AMG-416 produces enhanced receptor activation, supporting the potential for combination therapies. These findings advance the development of CaSR-targeted theragnostic agents for noninvasive imaging and treatment of CaSR-related pathologies.