N(ω)-hydroxy-nor-L-arginine (nor-NOHA), an arginase inhibitor, has therapeutic potential in the treatment of cardiovascular and obstructive airway diseases. Nor-NOHA is a reversible, competitive arginase inhibitor. The affinity of nor-NOHA for the to the arginase active site was found in the nanomolar range. Nor-NOHA has proven to be one of the strongest arginase inhibitors. Inhibition by nor-NOHA is ten times more potent on arginase II than on arginase I. The pharmacokinetics of nor-NOHA is characterized by high bioavailability, close to 100% after multiple dose and rapid elimination resulting in t1/2 of 15–30 min after intravenous and intraperitoneal administration to rats. Arginase inhibition with Nor-NOHA increased circulating arginine levels and decreased hepatic damage during liver I/R injury. Arginase blockade represents a potentially novel strategy to combat hepatic I/R injury associated with liver transplantation. Nor-NOHA is under investigation in clinical trial NCT02009527 (Arginase inhibition in ischemia-reperfusion injury).

FLOTEGATIDE F-18, a radiolabelled tripeptide with arginine-glycine-aspartic acid (R-G-D) motif, is a positron emission tomography (PET) tracer targeting integrin alpha-V/beta-3. It was under development as a diagnostic agent for cancer and atherosclerosis.

MK-0359 (L-454560) is a selective and potent type 4 phosphodiesterases (PDE4) inhibitor, which binds to both the apo-(Mg2+-free) and holoenzyme states of PDE4. This compound successfully has passed the phase II clinical trial for the treatment of asthma, Pulmonary Disease, Chronic Obstructive (COPD) and Rheumatoid Arthritis. However, there is no information about the further research of this drug.

SCY-635 is a nonimmunosuppressive cyclosporine-based analog that exhibits potent suppression of hepatitis C virus (HCV) replication. SCY-635 has reached the phase II clinical trial for the treatment of patients with hepatitis C Infection. In addition, in the preclinical model, the SCY-635 was studied for the treatment of hepatitis-B in USA.