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Amantadine

A drug approved for use both as an antiviral and an antiparkinsonian medication.

It consists of an adamantane backbone that has an amino group substituted at one of the four methyne positions.

Trade name Symmetrel

Pregnancy category US: C (Risk not ruled out)

Routes ofadministration-Oral

Bioavailability 86–90%

Protein binding 67%

Metabolism minimal

Elimination half-life 10–31 hours.

Excretion by urine

Amantadine is no longer recommended for treatment of influenza in the United States.

Its effectiveness as an antiparkinsonian drug is undetermined.

An extended release formulation is used to treat dyskinesia, a side effect of levodopa.

It has moderate effects on multiple sclerosis related fatigue.

Has associated central nervous system (CNS) side effects, due to its dopaminergic and adrenergic, and to a lesser extent anticholinergic activity

CNS side effects include: nervousness, anxiety, agitation, insomnia, difficulty in concentrating, and exacerbations of pre-existing seizure disorders and psychiatric symptoms in patients with schizophrenia or Parkinson’s disease.

Rarely skin rashes, and of suicidal ideation have also been reported.

Livedo reticularis has been reported as a side effect of amantadine use for Parkinson’s disease.

Its antiviral activity involves interference with the viral protein, M2, a proton channel.

Viruses enter cells via endocytosis, and localize in acidic vacuoles.

The acidification of the interior results in disassociation of ribonucleoproteins, and the initiation of viral replication.

It enters the barrel of the tetrameric M2 channel and blocking proton translocation.

Resistance to the drug class is a consequence of mutations to the pore-lining residues of the channel, which prevent it from inhibiting the channel in their usual way.

Influenza B strains possess a M2 channel with channel-facing side chain that

 

obstructs the channel by the binding of adamantine-class channel inhibitors.

This constriction is responsible for the ineffectiveness of this drug towards all circulating Influenza B strains

Has been used to treat traumatic brain injury, ranging from frontal lobe disorders including impulsiveness and disinhibition to trying to increase the pace of functional recovery.

Amantadine is a weak antagonist of the NMDA-type glutamate receptor.

It increases dopamine release, and blocks dopamine reuptake.

It has many effects in the brain, including release of dopamine and norepinephrine from nerve endings, it is a weak NMDA receptor antagonist, and is anticholinergic.

It is approved as an extended release formulation for the treatment of dyskinesia, an adverse effect of levodopa, that people with Parkinson’s experience.

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