Hello dear, Oxycodone is a semi synthetic opioid which acts relieve pain by acting through the central nervous system. Whether it is manufactured by Qualitest or Mylan, the active ingredient will be equally effective. But before changing the medication, it is always better to consult your treating Physician to avoid any unwanted side effects of the carrying agent used in the manufacture of the medication by the two different Pharmaceutical companies. Wishing you a good health. Take care.