| Metaxalone Predicted Metabolism Pathway |  | Metabolic | Metaxalone / Mesoheme |
| Metergoline Predicted Metabolism Pathway |  | Metabolic | Mesoheme / Metergoline |
| Methacholine Drug Metabolism |  | Metabolic | Methacholine |
| Methacholine M2 Bronchoconstriction Action Pathway |  | Drug Action | ATP / Potassium cation / Calcium / Magnesium cation / Cyclic adenosine monophosphate / Methacholine |
| Methacholine M3 Bronchoconstriction Action Pathway |  | Drug Action | Calcium / Magnesium cation / Methacholine |
| Methacycline Action Pathway |  | Drug Action | Metacycline |
| Methadone Action Pathway |  | Drug Action | NADH / ATP / Methadone / Norepinephrine / Dopamine / Potassium cation / Calcium / Mesoheme / Formaldehyde |
| Methadone Metabolism Pathway |  | Drug Metabolism | NADH / Methadone / Mesoheme / Formaldehyde |
| Methadone NMDA Antagonism Action Pathway |  | Drug Action | L-Glutamine / Glutamic acid / Methadone / Calcium |
| Methadone Opioid Agonist Action Pathway |  | Drug Action | ATP / Methadone / Calcium / Magnesium cation / Cyclic adenosine monophosphate / gamma-Aminobutyric acid / Pyrophosphoric acid / Sar9, Met (O2)11-Substance P |
| Methadyl Acetate Action Pathway |  | Drug Action | ATP / Norepinephrine / Dopamine / Potassium cation / Calcium / Methadyl acetate |
| Methadyl acetate Opioid Agonist Action Pathway |  | Drug Action | ATP / Calcium / Magnesium cation / Methadyl acetate / Cyclic adenosine monophosphate / gamma-Aminobutyric acid / Pyrophosphoric acid / Sar9, Met (O2)11-Substance P |
| Methamphetamine Dopamine Reuptake Inhibitor Action Pathway |  | Drug Action | Pyridoxal phosphate / Ademetionine / Ascorbic acid / Tyrosine / Tryptophan / Sapropterin / Norepinephrine / Dopamine / Levodopa / Magnesium cation / Metamfetamine / Iron / Oxitriptan / Flavin adenine dinucleotide / Pyrroloquinoline Quinone |
| Methamphetamine Norepinephrine Reuptake Inhibitor Action Pathway |  | Drug Action | Pyridoxal phosphate / Ascorbic acid / Tyrosine / Norepinephrine / Dopamine / Levodopa / Metamfetamine / Iron / Flavin adenine dinucleotide / Pyrroloquinoline Quinone |
| Methamphetamine Serotonin Reuptake Inhibitor Action Pathway |  | Drug Action | Pyridoxal phosphate / Tryptophan / Sapropterin / Metamfetamine / Iron / Oxitriptan / Flavin adenine dinucleotide |
| Methantheline Predicted Metabolism Pathway |  | Metabolic | Methantheline / Mesoheme |
| Methapyrilene H1 Antihistamine Smooth Muscle Relaxation Action Pathway |  | Drug Action | Calcium / Magnesium cation / Methapyrilene |
| Methapyrilene H1-Antihistamine Action |  | Drug Action | Calcium / Methapyrilene |
| Methapyrilene H1-Antihistamine Blood Vessel Constriction Action Pathway |  | Drug Action | Arginine / Citrulline / Sapropterin / Nitric Oxide / Calcium / Magnesium cation / Mesoheme / Flavin adenine dinucleotide / Flavin mononucleotide / Methapyrilene |
| Methapyrilene H1-Antihistamine Immune Response Action Pathway |  | Drug Action | Calcium / Methapyrilene |
| Methdilazine H1 Antihistamine Smooth Muscle Relaxation Action Pathway |  | Drug Action | Methdilazine / Calcium / Magnesium cation |
| Methdilazine H1-Antihistamine Action |  | Drug Action | Methdilazine / Calcium |
| Methdilazine H1-Antihistamine Blood Vessel Constriction Action Pathway |  | Drug Action | Arginine / Citrulline / Sapropterin / Nitric Oxide / Methdilazine / Calcium / Magnesium cation / Mesoheme / Flavin adenine dinucleotide / Flavin mononucleotide |
| Methdilazine H1-Antihistamine Immune Response Action Pathway |  | Drug Action | Methdilazine / Calcium |
| Methionine Adenosyltransferase Deficiency |  | Disease | Pyridoxal phosphate / Tetrahydrofolic acid / Ademetionine / Choline / Adenosine phosphate / Serine / Methionine / Glycine / Cysteine / NADH / ATP / Adenosine / Potassium cation / Magnesium cation / Zinc / Putrescine / N,N-dimethylglycine / 4-methylthio-2-oxobutanoic acid / Flavin adenine dinucleotide / Spermidine / Pyrophosphoric acid / L-Homoserine / 2-Oxobutanoic Acid |