| Miscellaneous Central Nervous System Agents | Not Available | 13 | 88 | Details |
| Miscellaneous Derivatives | Not Available | 1 | 14 | Details |
| Miscellaneous General Anesthetics | Not Available | 3 | 41 | Details |
| Miscellaneous GI Drugs | Not Available | 14 | 43 | Details |
| Miscellaneous Local Anti-infectives | Not Available | 23 | 164 | Details |
| Miscellaneous Skeletal Muscle Relaxants | Not Available | 2 | 15 | Details |
| Miscellaneous Therapeutic Agents | Not Available | 29 | 208 | Details |
| Miscellaneous Vasodilatating Agents | Not Available | 4 | 38 | Details |
| Mitochondrial benzodiazepine receptor (MBR) agonists | Not Available | 0 | 0 | Details |
| Mitogen-activated protein kinase (MEK) inhibitors | Not Available | 5 | 46 | Details |
| Mitogen-Activated Protein Kinase 14, antagonists & inhibitors | Not Available | 4 | 3 | Details |
| Mitogen-Activated Protein Kinase Kinase 1 Inhibitors | Not Available | 1 | 15 | Details |
| Mitogen-Activated Protein Kinase Kinase 2 Inhibitors | Not Available | 1 | 15 | Details |
| Mitogen-Activated Protein Kinases, antagonists & inhibitors | Not Available | 1 | 1 | Details |
| Mitogens | Substances that stimulate mitosis and lymphocyte transformation. They include not only ... more | 3 | 10 | Details |
| Mitomycins | A group of methylazirinopyrroloindolediones obtained from certain Streptomyces strains.... more | 2 | 6 | Details |
| Mitosis Modulators | Agents that affect MITOSIS of CELLS. | 27 | 151 | Details |
| Mitotic inhibitors | Not Available | 0 | 0 | Details |
| Mixed Agonist / Antagonist Opioids | Not Available | 7 | 33 | Details |
| Mixed Function Oxygenases | Widely distributed enzymes that carry out oxidation-reduction reactions in which one at... more | 2 | 11 | Details |
| Mixed opiate receptor agonists/antagonists | Not Available | 0 | 0 | Details |
| Mixed sodium/potassium channel blockers | Not Available | 0 | 0 | Details |
| Moderate Risk QTc-Prolonging Agents | Drugs that have demonstrated moderate QTc interval prolongation in either animal or hum... more | 122 | 1218 | Details |
| Molecular Chaperones | A family of cellular proteins that mediate the correct assembly or disassembly of polyp... more | 3 | 1 | Details |
| Molecular Probes | A group of atoms or molecules attached to other molecules or cellular structures and us... more | 12 | 26 | Details |