Oat grass pollen (Arrhenatherum elatius) obeticholic acid obinutuzumab ocrelizumab octocog alfa octreotide acetate odevixibat sesquihydrate oestrogens, conjugated ofatumumab ofloxacin olanzapine olanzapine pamoate monohydrate olaparib olipudase alfa olive oil, refined olmesartan medoxomil olodaterol hydrochloride olopatadine hydrochloride olopatadine hydrochloride olsalazine sodium omalizumab omega-3-acid ethyl esters 90 omega-3-acid triglycerides omeprazole omeprazole magnesium omeprazole sodium onasemnogene abeparvovec ondansetron ondansetron hydrochloride dihydrate opicapone opium tincture oritavancin diphosphate orlistat ornithine orphenadrine hydrochloride oseltamivir oseltamivir phosphate osilodrostat phosphate osimertinib mesylate ospemifene oxaliplatin oxazepam oxcarbazepine oxerutins oxybuprocaine hydrochloride oxybutynin oxybutynin hydrochloride oxycodone hydrochloride oxymetazoline hydrochloride oxytetracycline calcium oxytetracycline dihydrate oxytetracycline hydrochloride oxytocin ozanimod hydrochloride