O-acetylserine - Oxz
- O-acetylserine - Octamethylenediamine
- Octanoate - Ohmefentanyl
- Oir - Olopatadine
- Olsalazine - Optipranolol
- Or486 - Ota
- Ote - Oxandrolone
- Oxaprozin - Oxr
- Oxtriphylline - Oxytetracycline
- Oxytetracycline (anh - Oxz