NSAIDs such as naproxen are nonselective inhibitors of the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. These enzymes produce the prostaglandins responsible for pain, in ammation, and fever . Naproxen is characterized by its poor water solubility, and is sold commercially as the sodium salt form in order to increase the absorption rate. In recent times, polymeric conjugated drugs have emerged to improve the bioavailability of drugs while reducing adverse e ects. Standard polymeric prodrugs are created using a polymer carrier to which a drug is covalently bound to. Such conjugated drugs exist as a method for modifying pharmacokinetic and biodistribution properties of compounds . Using a polymeric conjugation method to increase overall stability can decrease the required dosage of a drug, reducing the potential toxicity and adverse e ects of a drug, increasing the therapeutic e cacy. For such conjugation procedure polyethylene glycol (PEG) was chosen due to its water-soluble and nontoxic behavior as well as the increased potential for bioavailability . Naproxen was selected as the molecular drug which was covalently linked to PEG for preparing Naproxen-PEG ester via Steglich Esteri cation. Additionally, chromatographic and spectrophotometric evaluation of drug release from naproxen-PEG conjugate in various media demonstrate the capacity for extended pharmacological e ect, due to a greater release pro le.