How Do Adenosine Antagonists Work?

Adenosine antagonists or adenosine receptor antagonists are a new drug class approved to be used as an add-on treatment to levodopa and carbidopa in patients with Parkinson’s disease (PD). Dopamine is a neurotransmitter in the brain that controls and coordinates movements. When nerve cells that release dopamine are damaged, dopamine levels decrease and lead to symptoms of PD, a neurological disorder that affects movements.

Adenosine agonists are used to treat “off” episodes (time period when the existing medicines do not work, and symptoms worsen) and decrease the symptoms.

Istradefylline is an adenosine antagonist approved by the FDA as an add-on therapy for PD.

The exact mechanism of action of istradefylline in PD is unknown. Istradefylline selectively binds to and inhibits adenosine A2A receptors. These receptors are G-protein-coupled receptors present in the basal ganglia, a part of the brain that controls movements. Basal ganglia are affected and degenerated in patients with PD, so these patients have severe movement disorders.

Adenosine antagonists are given as oral tablets to treat "off" episodes in PD.

Side effects associated with adenosine antagonists include:

• Dyskinesia (abnormal involuntary movements of the muscles)
• Constipation
• Nausea 
• Dizziness
• Hallucinations
• Diarrhea
• Insomnia
• Decreased appetite
• Upper respiratory tract infections
• Skin rash
• Elevated liver enzymes
• Hyperglycemia (high blood glucose)
• Increased urea levels

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of adenosine antagonists include:

• Istradefylline 
• Nourianz