| Obesity, drug therapy | Not Available | 1 | 1 | Details |
| Ocimum | A plant genus of the family LAMIACEAE. Ocimum gratissimum is the source of ocimum oil. | 0 | 0 | Details |
| OCT1 inhibitors | Inhibitors of the OCT1 transporter | 96 | 1603 | Details |
| OCT1 substrates | Substrates of the OCT1 transporter. | 55 | 832 | Details |
| OCT2 Inhibitors | Drugs which inhibitor organic cation transporter 2. | 118 | 2065 | Details |
| OCT2 Substrates | Not Available | 45 | 585 | Details |
| OCT2 Substrates with a Narrow Therapeutic Index | Not Available | 8 | 107 | Details |
| Octanols | Isomeric forms and derivatives of octanol (C8H17OH). | 1 | 1 | Details |
| Ocular Disorders | Not Available | 2 | 7 | Details |
| Ocular Vascular Disorder Agents | Not Available | 9 | 22 | Details |
| Odorants | Not Available | 1 | 1 | Details |
| Odors | Not Available | 0 | 0 | Details |
| Oenothera | A plant genus of the family ONAGRACEAE. Members contain oenotheins. | 1 | 5 | Details |
| Oenothera biennis | Not Available | 0 | 0 | Details |
| Oils | Unctuous combustible substances that are liquid or easily liquefiable on warming, and a... more | 49 | 116 | Details |
| Oils, Volatile | Oils which evaporate readily. The volatile oils occur in aromatic plants, to which they... more | 6 | 6 | Details |
| Ointment Bases | Various mixtures of fats, waxes, animal and plant oils and solid and liquid hydrocarbon... more | 1 | 0 | Details |
| Ointments | Not Available | 4 | 8 | Details |
| Oleaceae | A plant family of the order Lamiales. The leaves are usually opposite and the flowers u... more | 2 | 7 | Details |
| Oleic Acids | A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 ca... more | 2 | 16 | Details |
| Oligodeoxyribonucleotides, Antisense | Short fragments of DNA that are used to alter the function of target RNAs or DNAs to wh... more | 3 | 5 | Details |
| Oligomycins | A closely related group of toxic substances elaborated by various strains of Streptomyc... more | 1 | 0 | Details |
| Oligonucleotide Telomerase Inhibitor | Not Available | 1 | 7 | Details |
| Oligonucleotides | Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a sh... more | 43 | 53 | Details |
| Oligopeptides | Peptides composed of between two and twelve amino acids. | 104 | 304 | Details |