| Antazoline H1-Antihistamine Action |  | Drug Action | Calcium / Antazoline |
| Antazoline H1-Antihistamine Blood Vessel Constriction Action Pathway |  | Drug Action | Arginine / Citrulline / Sapropterin / Nitric Oxide / Calcium / Magnesium cation / Mesoheme / Flavin adenine dinucleotide / Flavin mononucleotide / Antazoline |
| Antazoline H1-Antihistamine Immune Response Action Pathway |  | Drug Action | Calcium / Antazoline |
| Anti-inflammatory pathway |  | Disease | L-Glutamine / Tryptophan / Nitric Oxide / Epinephrine / Hydrocortisone / Formic acid / Kynurenine / Mesoheme / Corticotropin |
| Antihemophilic Factor Human Action Pathway |  | Drug Action | Calcium / Antihemophilic factor human |
| Antihemophilic Factor Human Recombinant Action Pathway |  | Drug Action | Antihemophilic factor, human recombinant / Calcium |
| Antipyrine Action Pathway |  | Drug Action | Glutamic acid / Glutathione / Dinoprostone / Calcium / Magnesium cation / Antipyrine / Zinc / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Antipyrine NSAID Action Pathway |  | Drug Action | Glutathione / Dinoprostone / Calcium / Antipyrine / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Antipyrine Predicted Metabolism Pathway |  | Metabolic | Antipyrine / Mesoheme |
| Antrafenine Action Pathway |  | Drug Action | Glutamic acid / Glutathione / Dinoprostone / Calcium / Magnesium cation / Antrafenine / Zinc / Prostaglandin D2 / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Antrafenine Anti-inflammatory Action Pathway |  | Drug Action | Glutathione / Dinoprostone / Calcium / Antrafenine / Mesoheme / Prostaglandin G2 / Arachidonic Acid |
| Apixaban Action Pathway (new) |  | Drug Action | Calcium / Apixaban |
| Apomorphine Mechanism of Action Action Pathway |  | Drug Action | Pyridoxal phosphate / Tyrosine / ATP / Apomorphine / Dopamine / Levodopa / Calcium / Magnesium cation / Iron / Cyclic adenosine monophosphate / Pyrophosphoric acid |
| Apoptosis Signaling |  | Signaling | Calcium / Zinc / Hydroxychloroquine / 1D-myo-inositol 1,3,4-trisphosphate / Mesoheme |
| 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 |
| Aprotinin Kallikrein Antifibrinolytic Action Pathway |  | Drug Action | Calcium / Aprotinin |
| Aprotinin Plasminogen Antifibrinolytic Action Pathway |  | Drug Action | 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 | Arbekacin |
| Arbutamine Action Pathway |  | Drug Action | ATP / Arbutamine / Potassium cation / Calcium |
| Arbutamine Action Pathway |  | Drug Action | ATP / Arbutamine / Calcium |
| Ardeparin Action Pathway |  | Drug Action | Ardeparin / Phylloquinone / Calcium |
| Ardeparin Action Pathway (new) |  | Drug Action | Ardeparin / Calcium |