| Alvimopan Action Pathway |  | Drug action | ATP / Norepinephrine / Dopamine / Potassium cation / Calcium / Alvimopan |
| Amikacin Action Pathway |  | Drug action | Histidine / Adenosine phosphate / Methionine / Leucine / Threonine / Alanine / Valine / Isoleucine / ATP / Proline / Asparagine / Amikacin / Guanosine-5'-Monophosphate / Cytidine-5'-Triphosphate / Uridine monophosphate / D-Serine / Pyrophosphoric acid |
| Amiloride Action Pathway |  | Drug action | Cysteine / Amiloride / Potassium cation / Urea |
| Amino Sugar Metabolism |  | Metabolic | Pyruvic acid / L-Glutamine / N-Acetylglucosamine / Glutamic acid / ATP / Glucosamine / Magnesium cation / Phosphoenolpyruvate / Cytidine-5'-Triphosphate / Acetic acid / Uridine-5'-Diphosphate / Pyrophosphoric acid |
| Aminocaproic Acid Action Pathway |  | Drug action | Aminocaproic acid / Phylloquinone / Calcium |
| Amiodarone Action Pathway |  | Drug action | ATP / Amiodarone / Potassium cation / Calcium / Magnesium cation |
| Amlodipine Action Pathway |  | Drug action | ATP / Amlodipine / Potassium cation / Calcium / Magnesium cation |
| Ammonia Recycling |  | Metabolic | Pyridoxal phosphate / Tetrahydrofolic acid / Histidine / Pyruvic acid / Biotin / Aspartic acid / L-Glutamine / Adenosine phosphate / Serine / Glutamic acid / Glycine / NADH / ATP / Asparagine / Magnesium cation / trans-urocanic acid / Flavin adenine dinucleotide / Pyrophosphoric acid |
| Androgen and Estrogen Metabolism |  | Metabolic | NADH / Testosterone / Estrone / Estradiol / Calcium / Androstenedione / Formic acid / Mesoheme / Uridine-5'-Diphosphate / Estrone sulfate / Prasterone sulfate / 5beta-dihydrotestosterone |
| Androstenedione Metabolism |  | Metabolic | NADH / Testosterone / Estrone / Androstenedione / Androstanedione / Formic acid / Mesoheme / Aetiocholanolone / Uridine-5'-Diphosphate / Etiocholanedione |
| Angiotensin Metabolism |  | Physiological | Zinc |
| Anileridine Action Pathway |  | Drug action | ATP / Norepinephrine / Anileridine / Dopamine / Potassium cation / Calcium |
| Anistreplase Action Pathway |  | Drug action | Anistreplase / Phylloquinone / Calcium |
| Antazoline H1-Antihistamine Action |  | Drug action | Calcium / Antazoline |
| Antipyrine Action Pathway |  | Drug action | Glutamic acid / Glutathione / Dinoprostone / Calcium / Magnesium cation / Antipyrine / Zinc / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Antrafenine Action Pathway |  | Drug action | Glutamic acid / Glutathione / Dinoprostone / Calcium / Magnesium cation / Antrafenine / Zinc / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Apoptotic DNA Fragmentation and Tissue Homeostasis |  | Signaling | Zinc |
| Apparent Mineralocorticoid Excess Syndrome |  | Disease | NADH / Progesterone / Hydrocortisone / Mesoheme / Cholesterol / Corticosterone / 20-hydroxycholesterol |
| Aprotinin Action Pathway |  | Drug action | Phylloquinone / Calcium / Aprotinin |
| Arachidonic Acid Metabolism |  | Metabolic | Glutamic acid / Glutathione / Dinoprostone / Calcium / Magnesium cation / Zinc / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Arbekacin Action Pathway |  | Drug action | Histidine / Adenosine phosphate / Methionine / Leucine / Threonine / Alanine / Valine / Isoleucine / ATP / Proline / Asparagine / Guanosine-5'-Monophosphate / Cytidine-5'-Triphosphate / Uridine monophosphate / D-Serine / Pyrophosphoric acid / Arbekacin |
| Arbutamine Action Pathway |  | Drug action | ATP / Arbutamine / Potassium cation / Calcium / Magnesium cation |
| Ardeparin Action Pathway |  | Drug action | Ardeparin / Phylloquinone / Calcium |
| Argatroban Action Pathway |  | Drug action | Argatroban / Phylloquinone / Calcium |
| Arginine and Proline Metabolism |  | Metabolic | Pyridoxal phosphate / Ademetionine / Arginine / Aspartic acid / Ornithine / Adenosine phosphate / Succinic acid / Glutamic acid / Glycine / Creatine / Citrulline / NADH / ATP / Proline / Sapropterin / Nitric Oxide / Mesoheme / Glycocyamine / 3,4-Dihydro-2h-Pyrrolium-5-Carboxylate / N(5)-[(hydroxyamino)(imino)methyl]-L-ornithine / Flavin adenine dinucleotide / Flavin mononucleotide / Urea / Pyrophosphoric acid / Maleic acid / 4-Carboxy-4-Aminobutanal |