However, evaluating this technology poses challenges due to the multitude of vari­ables involved, making broad comparisons between individual designs nearly impractical [156]. Understanding the mechanism of drug delivery is crucial for selecting the appropriate drug and achieving a time-ordered release. Polymeric sys­tems serve as efcient drug carriers due to their ability to provide a framework for controlled drug release and protect the drug from degradation before it exerts its therapeutic effects. The mechanism of drug release from the polymer substrate can be categorized into physical and chemical mechanisms. The physical mechanism involves drug release through permanent polymer layers, dissolution or degradation of the polymer, permeation pressure, and ion exchange processes. On the other hand, the chemical mechanism results from the breakage of covalent bonds due to chemical or enzymatic degradation [7]. The evolution of drug-polymer systems has transitioned from nonbiodegradable to biodegradable polymers, where the latter has become a signicant player in drug-eluting systems. The drug diffusion process in nonbiodegradable polymers was controlled by the concentration gradient. In con­trast, biodegradable polymers offer three major release mechanisms based on the type of polymer: diffusion (for permanent polymers), swelling, and degradation. These mechanisms highlight the versatility and adaptability of polymeric systems in achieving controlled and effective drug delivery [157].

Characterizing drug-eluting composites is essential to understanding their perfor­mance, ensuring their safety, and optimizing their efcacy in biomedical applica­tions. Various characterization methods are employed to assess different aspects of these composites, ranging from their structural integrity to drug release kinetics. The following discusses various methods used to characterize the properties of drug-eluting composites, as mentioned in Table10.5.

materials. In the context of drug-eluting composites, where the integration of drugs or therapeutic agents within a matrix is crucial, precise structural analysis becomes imperative. Techniques such as scanning electron microscopy (SEM) [170] enable researchers to examine the surface morphology and microstructure, providing insights into pore size, the distribution of therapeutic agents, and matrix homogene­ity [171]. This information is invaluable for optimizing drug loading, release kinet­ics, and overall performance. Chemical composition analysis, facilitated by methods like Fourier Transform Infrared Spectroscopy (FTIR), helps unravel molecular interactions within the composite [172]. FTIR identies functional groups in the matrix and drug components, offering insights into potential degradation products and ensuring compatibility between drugs and polymers. The mechanical properties of drug-eluting composites, assessed through tensile, compression, and exural tests, are critical for determining the suitability of these materials for specic appli­cations. For instance, stiffness can inuence drug release kinetics, and understand­ing these mechanical aspects aids in tailoring the composite for optimal performance. Overall, a multidimensional characterization approach is essential in elucidating the intricate features of drug-eluting composites, paving the way for the development of efcient and tailored drug delivery systems in biomedical applications. Table10.6 shows the advantages and disadvantages of various characterization methods [173].

The other methods for drug stability analysis, swelling and erosion studies, electro­chemical analysis, and thermal analysis are also discussed by various researchers [193–195]. Stability studies inform guidelines on storage and handling while swell­ing and erosion studies reveal material responses to physiological conditions. Electrochemical and thermal analyses provide insights into corrosion resistance, tissue interaction, and thermal stability, ensuring the long-term safety and efcacy of drug-eluting composite materials. Differential Scanning Calorimetry (DSC) or Thermogravimetric Analysis (TGA) techniques help evaluate the thermal stability of drug-eluting composites and provide insights into their response to temperature changes [183]. By employing these characterization methods, researchers gain a comprehensive understanding of the structural, chemical, mechanical, and biologi­cal properties of drug-eluting composites. This knowledge is crucial for optimizing the design, fabrication, and performance of these materials in diverse biomedical applications [196].