Amantadine, sold under the brand name Gocovri among others, is a medication used to treat dyskinesia associated with parkinsonism and influenza caused by type A influenzavirus, though its use for the latter is no longer recommended due to widespread drug resistance. It acts as a nicotinic antagonist, dopamine agonist, and noncompetitive NMDA antagonist. The antiviral mechanism of action is antagonism of the influenzavirus A M2 proton channel, which prevents endosomal escape (i.e. the release of viral genetic material into the host cytoplasm).Amantadine was first used for the treatment of influenza A. After antiviral properties were initially reported in 1963, amantadine received approval for prophylaxis against the influenza virus A in 1976. However, amantadine-resistant influenza viruses were first reported during the 1980 influenza A epidemic and resistance frequency continued to rise into the early 2000s. Currently, amantadine is no longer recommended for the treatment of influenza A due to a high level of amantadine resistance among circulating influenza A viruses. In 1973, the Food and Drug Administration (FDA) approved amantadine for use in the treatment of Parkinsons disease. In 2017, the extended release formulation was approved for use in the treatment of levodopa-induced dyskinesia. Off-label uses include improvement of fatigue in multiple sclerosis and accelerating the rate of functional recovery and arousal following a brain injury.Amantadine has a mild side effect profile. Common neurological side effects include drowsiness, light headedness, dizziness, and confusion. Due to its effects on the central nervous system, it should not be combined with additional CNS stimulants or anticholinergic drugs.
The extended release amantadine formulation is commonly used to treat dyskinesias in people receiving levodopa therapy for Parkinsons disease. A 2003 Cochrane review had concluded there was insufficient evidence to prove the safety or efficacy of amantadine to treat dyskinesia.In 2008, the World Health Organization reported amantadine is not effective as a stand-alone parkinsonian therapy, but recommended it could be used in combination therapy with levodopa. Influenza A
Amantadine is not recommended for treatment or prophylaxis of influenza A in the United States. Amantadine has no effect preventing or treating influenza B infections. The US Centers for Disease Control and Prevention found 100% of seasonal H3N2 and 2009 pandemic flu samples were resistant to adamantanes (amantadine and rimantadine) during the 2008–2009 flu season.The U.S. Centers for Disease Control and Prevention (CDC) guidelines recommend only neuraminidase inhibitors for influenza treatment and prophylaxis. The CDC recommends against amantadine and rimantadine to treat influenza A infections.Similarly, the 2011 World Health Organization (WHO) virology report showed all tested H1N1 influenza A viruses were resistant to amantadine. WHO guidelines recommend against use of M2 inhibitors for influenza A. The continued high rate of resistance observed in laboratory testing of influenza A has reduced the priority of M2 resistance testing.A 2014 Cochrane review did not find evidence for efficacy or safety of amantadine used for the prevention or treatment of influenza A.

Extra-pyramidal side effects
An extended release formulation is used to treat levodopa-induced dyskinesia in patients with Parkinsons disease.