Istradefylline is a first-in-class adenosine A2A receptor antagonist antiparkinsonian agent and has been marketed as the brand name NOURIAST® in Japan since May 30, 2013. NOURIAST is indicated for the improvement of wearing-off phenomena in patients with Parkinson’s disease on concomitant treatment with levodopa-containing products.

Caffeine is a methylxanthine alkaloid found in the seeds, nuts, or leaves of a number of plants native to South America and East Asia that is structurally related to adenosine and acts primarily as an adenosine receptor antagonist with psychotropic and anti-inflammatory activities. Upon ingestion, caffeine binds to adenosine receptors in the central nervous system (CNS), which inhibits adenosine binding. This inhibits the adenosine-mediated downregulation of CNS activity; thus, stimulating the activity of the medullary, vagal, vasomotor, and respiratory centers in the brain. The anti-inflammatory effects of caffeine are due the nonselective competitive inhibition of phosphodiesterases. Caffeine is used by mouth or rectally in combination with painkillers (such as aspirin and acetaminophen) and a chemical called ergotamine for treating migraineheadaches. It is also used with painkillers for simple headaches and preventing and treating headaches after epidural anesthesia. Caffeine creams are applied to the skin to reduce redness and itching in dermatitis. Healthcare providers sometimes give caffeine intravenously (by IV) for headache after epidural anesthesia, breathing problems in newborns, and to increase urine flow. In foods, caffeine is used as an ingredient in soft drinks, energy drinks, and other beverages.

Vipadenant (V2006) is a small molecule, adenosine A2A receptor antagonist that was being investigated in Parkinson's disease. Due to safety concerns development ceased in 2010 and the rights were regained from Biogen Idec in 2011 with no further investment made. In October 2014, RedoxTherapies licensed Vipadenant as it has the potential to disrupt an immunosuppressive mechanism of tumour protection, generating improved efficacy for immunotherapies of certain cancers when used in combination with other drugs.

Piclidenoson (CF101), generically known as IB-MECA (methyl 1-[N6-(3-iodobenzyl)-adenin-9-yl]-b-D-ribofuronamide), is an oral small molecule drug formulated in a tablet. The activity of CF101 as an anti-inflammatory agent has been tested in a number of different experimental models including adjuvant and collagen induced arthritis and inflammatory bowel disease. CF101 is a highly specific agonist at the A3AR known to induce a robust anti-inflammatory effect in different experimental animal models. The CF101 mechanism of action entails down-regulation of the NF-κB-TNF-α signaling pathway, resulting in inhibition of pro-inflammatory cytokine production and apoptosis of inflammatory cells. Piclidenoson is currently being developed for the treatment of autoimmune inflammatory diseases like RA and psoriasis, hoping to replace the current standard of care, methotrexate (MTX). Can-Fite has tested CF101 in a number of Phase II studies in different diseases. A Phase II study in Psoriasis successfully met its primary endpoint showing that CF101 effectively ameliorated disease symptoms. In an interim analysis of the Phase II/III study the data justified full enrollment of the study. Phase II studies in Rheumatoid Arthritis (RA) demonstrated efficacy of CF101 given as a monotherapy. Moreover, a direct correlation between A3AR at baseline and patients’ response to CF101, suggesting its utilization as a predictive biomarker. Piclidenoson is headed into Phase 3 trials for RA and psoriasis.

Tonapofylline is a selective oral adenosine A, receptor antagonist, for the potential treatment of congestive heart failure. Oral tonapofylline over the dose range of 3 to 225 mg/day produced significant increases in sodium excretion in patients with stable heart failure without causing kaliuresis or reducing renal function. Tonapofylline may be useful in the clinical setting for the prevention of kidney failure induced by nephrotoxic agents such as cisplatin. Tonapofylline may be renoprotective in the setting of concomitant treatment with a loop-diuretic. Adverse effects were generally mild. Tonapofylline had been in phase III clinical trial for the treatment of acute heart failure. However, this development was discontinued.