I have not heard of narcotic drugs having this effect of clearing skin.
If your skin is oily, white vinegar is effective as an astringent. Or try a tea tree oil soap. Eat a healthy diet, high in vegetables, fruits, and lean, preferably organic meats, poultry and fish.
Find out if you have food allergies and avoid problem foods.
Thew oxycontin has nothing whatsoever to do with the acne. That being said, get an hva1c. Diabetes can cause acne.