In order to evaluate the potential of Naproxen-PEG conjugate as a drug delivery system in the body, the release pro le was also obtained in an acidic environment. The same procedure was repeated, where a solution of .1M HCl was prepared and 1g of Naproxen and Naproxen-PEG were added to the solution in separate beakers. A sample of each solution was taken and added to a cuvette for spectrophotometric determination of concentration at 262 nm. It should be noted that naproxen is practically insoluble in water at low pH. Naproxen-PEG conjugate demonstrates capacity for increased dispersion in a low pH environment. Naproxen-PEG expresses prolonged release behavior compared to the standard naproxen counterpart.