| Metolazone Action Pathway |  | Drug Action | Metolazone / Potassium cation / Calcium |
| Metolazone Action Pathway (old) |  | Drug Action | Cysteine / Metolazone / Potassium cation / Urea |
| Metoprolol Action Pathway |  | Drug Action | ATP / Metoprolol / Potassium cation / Calcium |
| Metoprolol Action Pathway (New) |  | Drug Action | ATP / Metoprolol / Calcium |
| Metrifonate Action Pathway |  | Drug Action | Choline / Calcium / Magnesium cation / Acetylcholine / Acetic acid / Metrifonate |
| Mevalonate Pathway |  | Metabolic | ATP / Magnesium cation / Dimethylallyl Diphosphate / Geranyl Diphosphate / Flavin adenine dinucleotide / Flavin mononucleotide / Pyrophosphoric acid / ISOPENTENYL PYROPHOSPHATE / Farnesyl diphosphate |
| Mevalonic Aciduria |  | Disease | Cholecalciferol / ATP / Magnesium cation / Iron / Dimethylallyl Diphosphate / Formic acid / Geranyl Diphosphate / Mesoheme / Flavin adenine dinucleotide / Palmitic Acid / Pyrophosphoric acid / Cholesterol / ISOPENTENYL PYROPHOSPHATE / Farnesyl diphosphate |
| Mevalonic Aciduria |  | Disease | Cholecalciferol / ATP / Magnesium cation / Iron / Dimethylallyl Diphosphate / Formic acid / Geranyl Diphosphate / Mesoheme / Flavin adenine dinucleotide / Palmitic Acid / Pyrophosphoric acid / Cholesterol / ISOPENTENYL PYROPHOSPHATE / Farnesyl diphosphate |
| Mexiletine Action Pathway |  | Drug Action | ATP / Mexiletine / Potassium cation / Calcium |
| Mexiletine Action Pathway (New) |  | Drug Action | Mexiletine / Potassium cation / Calcium / Cyclic adenosine monophosphate |
| Mianserin H1 Antihistamine Smooth Muscle Relaxation Action Pathway |  | Drug Action | Calcium / Magnesium cation / Mianserin |
| Mianserin H1-Antihistamine Blood Vessel Constriction Action Pathway |  | Drug Action | Arginine / Citrulline / Sapropterin / Nitric Oxide / Calcium / Magnesium cation / Mesoheme / Flavin adenine dinucleotide / Flavin mononucleotide / Mianserin |
| Mianserin H1-Antihistamine Immune Response Action Pathway |  | Drug Action | Calcium / Mianserin |
| Mianserin Predicted Metabolism Pathway |  | Metabolic | Mesoheme / Mianserin |
| Micafungin Action Pathway |  | Drug Action | Micafungin |
| Miconazole Action Pathway |  | Drug Action | Miconazole / Magnesium cation / Formic acid / Mesoheme / Flavin adenine dinucleotide / Ergosterol / Pyrophosphoric acid / Farnesyl diphosphate |
| Miconazole Predicted Metabolism Pathway |  | Metabolic | Miconazole / Mesoheme |
| Micronomicin Predicted Metabolism Pathway |  | Metabolic | Mesoheme / Micronomicin |
| Midazolam Action Pathway |  | Drug Action | Pyridoxal phosphate / Glutamic acid / ATP / Midazolam / Calcium / Magnesium cation / Cyclic adenosine monophosphate / gamma-Aminobutyric acid / Pyrophosphoric acid |
| Midostaurin Action Pathway |  | Drug Action | Calcium / Midostaurin |
| Mifepristone Predicted Metabolism Pathway |  | Metabolic | Mifepristone / Mesoheme |
| Migalastat Drug Metabolism |  | Metabolic | Migalastat |
| Miglitol Drug Metabolism |  | Metabolic | Miglitol |
| Miglustat Drug Metabolism |  | Metabolic | Miglustat |
| Milnacipran SNRI - Norepinephrine reuptake Inhibition Action Pathway |  | Drug Action | Pyridoxal phosphate / Ascorbic acid / Tyrosine / Norepinephrine / Dopamine / Levodopa / Calcium / Iron / Pyrroloquinoline Quinone / Milnacipran |