| Record No. | Name | No. of Entries |
| 601 | Ochotensine | 1 |
| 602 | Ocoteine | 1 |
| 603 | Oliveroline | 2 |
| 604 | Opium | 8 |
| 605 | OXOAPORPHINE | 1 |
| 606 | Oxoglaucine | 1 |
| 607 | Oxoglaucine methiodide | 1 |
| 608 | Oxophoebine | 1 |
| 609 | Oxopurpureine | 1 |
| 610 | Oxyacanthine | 1 |
| 611 | Oxycodone | 2 |
| 612 | Oxycodone hydrochloride hydrate | 1 |
| 613 | Oxycodone terephthalate | 2 |
| 614 | Oxycodone-acetaminophen | 1 |
| 615 | Oxycolchicine | 1 |
| 616 | Oxymorphone | 6 |
| 617 | Palmatine | 4 |
| 618 | Palmatine chloride hydrate | 1 |
| 619 | Papaveraldine | 2 |
| 620 | Papaverine | 9 |
| 621 | Papaverine adenylate | 1 |
| 622 | Papaverine codecarboxylate | 1 |
| 623 | Papaverine hydrogen sulphate | 1 |
| 624 | Papaverine lauryl sulfate | 1 |
| 625 | Papaverinol | 1 |