DEVELOPMENT AND EVALUATION OF HYDROGEL FOR TOPICAL PAIN RELIEF: A COMPREHENSIVE REVIEW

Hydrogels are semi-solid, three-dimensional polymeric systems capable of holding large amounts of water, making them ideal for topical drug delivery, especially in pain management. This review explores hydrogel formulation and its application in topical pain relief. Hydrogels are classified based on origin, polymer type, cross-linking method, and responsiveness to stimuli. Their advantages include biocompatibility, ease of application, and controlled drug release. However, limitations such as low loading capacity for hydrophobic drugs and risk of microbial contamination are noted. Preparation methods such as physical, chemical, and radiation cross-linking, along with grafting polymerization, are discussed. Each method provides unique properties suited to specific applications. The formulation process is outlined with emphasis on the functional role of each component. These include active pharmaceutical ingredients (e.g., NSAIDs, anesthetics), gelling agents (e.g., Carbopol, HPMC), pH adjusters, penetration enhancers, humectants, preservatives, and solvents. Each contributes to hydrogel performance, stability, and skin compatibility. A sample formulation using diclofenac sodium illustrates how these components combine into an effective gel for localized drug delivery. In conclusion, hydrogels offer a promising, patient-friendly approach to topical pain relief. Continued innovation in hydrogel systems may enhance future pain management strategies.