| HDAC class specificity | Potency | Route of administration | Clinical Status | Structure | ||
| Vorinostat | I, II, IV | nM | Oral | FDA approved (2006) |  | |
| Hydroxamate | Belinostat (PXD101) | I, II, IV | nM | Oral/intravenous | Phase I, II |  |
| Panobinostat (LBH589) | I, II, IV | nM | Oral | Phase II, III |  | |
| Benzamide | Entinostat (MS-275) | I | M | Oral | Phase II |  |
| Cyclic tetrapeptide | Depsipeptide (FK228, romidepsin) | I, II, IV | nM | Intravenous | FDA approved (2009) |  |