BACKGROUND The use of patient-controlled analgesia (PCA) allows patients to be managed at home and may increase the quality of life of patients with regard to drug administration. To ensure that intact drug is delivered to the patient in this setting, it is important to study its microbiological and physicochemical stability. Although these factors have been widely studied for many parenteral opioids, very few authors have investigated oxycodone stability associated with long-duration infusion in cancer patients. OBJECTIVE The aim of this study was to assess the microbiological and physicochemical stability of oxycodone hydrochloride solution in PCA devices and thereby to determine the feasibility of extending the expiration dates after mixing. METHODS Sixteen CADD reservoirs and 32 Rythmic reservoirs were filled aseptically with pure (10 mg/mL) and diluted (1 mg/mL) oxycodone solution. Three different vehicles (0.9% sodium chloride, water for injection, and 5% dextrose) were used for dilution. Among the PCA systems stored over 28 days at room temperature, 16 Rythmic reservoirs were protected from light. Microbiological stability was assessed by performing sterility tests. The physicochemical study was performed by determining aspect, pH, osmolality evolution, and weight. Drug concentrations were determined using the stability-indicating high performance liquid chromatography combined to ultraviolet detection technique. RESULTS There was no significant change in pH, weight, and osmolality values of any solutions. No precipitation or change in color was observed in any of the sample solutions. There was no significant loss of oxycodone, and no trace of degradation products was detected. CONCLUSIONS This study indicates that pure and diluted oxycodone solutions in the PCA systems are stable for 28 days at room temperature when prepared aseptically.