Therapeutic Drug Monitoring (TDM) is a clinical practice that involves measuring specific drug levels in a patient's bloodstream to ensure they are within a therapeutic range. This helps healthcare providers optimize medication dosages, enhancing effectiveness while minimizing side effects. TDM is particularly important for drugs with narrow therapeutic windows, where small changes in dosage can lead to significant differences in drug effects. By regularly monitoring drug levels, clinicians can make informed decisions about treatment adjustments. This process is essential for managing chronic conditions, such as epilepsy or heart disease, where maintaining the right drug concentration is crucial for patient safety and overall health.