The purpose of this study was to establish a clinically relevant specification for carbamazepine (CBZ) tablets, a classic narrow therapeutic index drug (NTID), within the Chinese population. By integrating physiologically based pharmacokinetic (PBPK) modeling with in vitro dissolution profiles and corresponding pharmacokinetic (PK) data, we developed an in vitro-in vivo relationship (IVIVR) by selecting an appropriate dissolution model, and the IVIVR model was validated using in vitro and in vivo data from external sources to ensure the reliability of the method. Parameter sensitivity analysis was used to examine how the critical parameters influence the drug's absorption fraction (F