Limitations: This safety classification applies only to preparations containing a combination of the two drugs oxycodone and naloxone. The same ATC-code (N02A A55) can in some countries be used for different combinations of oxycodone and other drugs, which in theory may be porphyrinogenic. Please refer to the classification and monograph of each individual substance. If the combination contains a substance which is not classified (NC) or has been classified as porphyrinogenic (PSP, PRP or P), the safety classification of such a combination as PNP is no longer valid. Combination products which contains the two substances oxycodone (ATC code: N02A A05) and naloxone (ATC code: V03A B15) are safety classified as Probably not porphyrinogenic (PNP), as both of them are safety classified as Probably not porphyrinogenic (PNP) separately. For more details please refer to the monographs of the two substances.