An antiviral agent, its mechanism of action is not known. As more direct dopamine agonists become available, this drug appears to be less appropriate for general use.

Other reported mechanism of action is

• Anticholinergic actions
• Delay of dopamine uptake by neural cells
• Release of dopamine from central neurons
• Blockade of N-methyl-D-aspartate (NMDA) receptors.
• It has only minimal effect on tremor; tolerance develops in 6-8 months.
• It is advocated to substitute or add when patient's early symptoms do not respond to anticholinergics.
• When given as a monotherapy for early minor symptoms, it reportedly results in a 20% to 40% global improvement in two third of patients.
• It is also effective in late stages of PD; patients who are getting maximal response from levodopa usually derive some additional benefits because of additive action of the two drugs.

• Leg swelling (particularly in elderly)
• Hallucinations