| Actins, antagonists & inhibitors | Not Available | 1 | 1 | Details |
| Actively Acquired Immunity | Not Available | 94 | 1 | Details |
| Activin Receptors | Receptors for ACTIVINS are membrane protein kinases belonging to the family of PROTEIN-... more | 2 | 4 | Details |
| Activin Signaling Inhibitor | Not Available | 2 | 6 | Details |
| Acute-Phase Proteins | Proteins that are secreted into the blood in increased or decreased quantities by hepat... more | 4 | 4 | Details |
| Acyclovir and prodrug | Not Available | 2 | 28 | Details |
| Acyl CoA cholesterol acyltransferase (ACAT) inhibitors | Not Available | 0 | 0 | Details |
| Acylfulven derivatives | Not Available | 0 | 0 | Details |
| Acyltransferases | Enzymes from the transferase class that catalyze the transfer of acyl groups from donor... more | 1 | 2 | Details |
| ADAM Proteins | A family of membrane-anchored glycoproteins that contain a disintegrin and metalloprote... more | 1 | 2 | Details |
| Adamantane Derivatives | Not Available | 1 | 13 | Details |
| Adamantanes | Adamantanes are a class of antiviral medications which are active against influenza A b... more | 2 | 14 | Details |
| ADAMTS Proteins | A subfamily of ADAMTS proteins that lack a protease domain. | 1 | 2 | Details |
| Adenine Nucleotides | Small molecules that are required for the catalytic function of ENZYMES. Many VITAMINS ... more | 48 | 567 | Details |
| Adeno-associated Viral Vector Therapies | This category contains approved and investigational gene therapies utilizing adeno-asso... more | 55 | 13 | Details |
| Adenosine A receptor agonists | Not Available | 6 | 6 | Details |
| Adenosine A1 Receptor Agonists | Not Available | 2 | 2 | Details |
| Adenosine A1 Receptor Antagonists | Compounds that bind to and block the stimulation of ADENOSINE A1 RECEPTORS. | 2 | 6 | Details |
| Adenosine A2 Receptor Agonists | Compounds that selectively bind to and activate ADENOSINE A2 RECEPTORS. | 4 | 4 | Details |
| Adenosine A2 Receptor Antagonists | Compounds that selectively bind to and block the activation of ADENOSINE A2 RECEPTORS. | 4 | 31 | Details |
| Adenosine A3 Receptor Antagonists | Compounds that selectively bind to and block the activation of ADENOSINE A3 RECEPTORS. | 1 | 1 | Details |
| Adenosine Deaminase | Not Available | 0 | 0 | Details |
| Adenosine Deaminase Inhibitors | Drugs that inhibit ADENOSINE DEAMINASE activity. | 2 | 3 | Details |
| Adenosine Kinase, antagonists & inhibitors | Not Available | 1 | 3 | Details |
| Adenosine Triphosphatases | A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usu... more | 1 | 1 | Details |