Objective: The objective of this paper is to investigate the application of differential equations in pharmacokinetics, with an emphasis on modeling and analyzing pharmacokinetic processes such as drug absorption, distribution, metabolism, and elimination. Materials and Methods: Various mathematical models and simulations were used in this paper to illustrate pharmacokinetic processes. Data from relevant literature, including scientific articles and books on pharmacokinetics, were analyzed. Differential equations were applied to model the dynamics of drug concentration in plasma and tissues over time. Results: The results of the analysis showed that differential equations enable precise modeling of changes in drug concentration within the body. Graphs were presented to illustrate how the drug concentration changes over time for different routes of administration (intravenous, oral, etc.). Additionally, simulation results were presented to demonstrate the effect of different doses on plasma drug concentration. Conclusion: Differential equations are, therefore, an essential part of pharmacokinetics, providing the structure and mathematical precision needed to understand the dynamics of drugs in the body. They are not only a tool for research and development but also for practical application in clinical settings, directly contributing to improved healthcare and patient treatment outcomes.