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Amantadine

Summary: Amantadine (Symmetrel®) is a medication that may be helpful for helping people with challenging behaviours in neurobehavioral disorders (e.g. traumatic brain injury, autism spectrum disorder) with poor executive functioning.
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What is Amantadine?

Amantadine (Symmetrel®) is a medication that may be helpful for helping people with challenging behaviours in neurobehavioral disorders (e.g. traumatic brain injury, autism spectrum disorder) with poor executive functioning.

It has the following features:

  • Glutamatergic antagonism, i.e. it inhibits the NMDA receptor by binding to it, thus preventing excessive NMDA excitation by the glutamate neurotransmitter. By preventing the toxic effects of excessive glutamatergic neurotransmission, it may thus be helpful with various brain conditions.
  • Enhancing dopamine function by enhancing dopamine release indirectly via antagonism of the NMDA receptor.

Amantadine has been around a while, having been originally approved in 1976 by the US Food and Drug Administration (FDA) as an antiviral drug to treat Influenza A, however it is no longer used for this purpose.

What Might It Be Helpful For?

Evidence suggests it may be helpful for the following:

  • Behaviours
    • Aggression, challenging behaviours
  • Symptoms:
    • Fatigue, distractibility, rigidity, arousal level, initiation, purposeful movement, attention and concentration, sequencing skills and processing time (Green, Hornyak, & Hurvitz, 2004).
  • Side effects
    • Counteracting excessive weight gain in children/youth on atypical antipsychotics
  • Brain conditions such as
    • Attention deficit hyperactivity disorder (ADHD)
    • Autism spectrum disorder (ASD)
    • Fetal alcohol spectrum disorders (FASD)
    • Depression: Amantadine has been used to augment treatment-resistant depression (Stryjer et al., 2003; Rogoz et al., 2007)
    • Obsessive-compulsive disorder (OCD)
    • Traumatic brain injury (TBI): Amantadine is felt to have neuroprotective properties.

What is the Dosage for Amantadine?

For adolescents and adults, typically, it is started at 25-50 mg daily and increased up to 200 mg daily. 

Side Effects

Amantadine is well tolerated in children, as those taking amantadine did not report more side effects than those on placebo (King, Wright, Handen, et al., 2001).

Side effects reported most frequently (5–10% incidence) include:

  • Nausea
  • Dizziness (lightheadedness)
  • Insomnia.

Side effects / adverse reactions reported less frequently (1–5%) include:

  • Confusion,
  • Somnolence,
  • Anorexia,
  • Dry mouth, constipation, headache, orthostatic hypotension, agitation, irritability and hallucinations.

Rarer side effects (0.1–1%) include:

  • Psychosis/ paranoia, delusions, abnormal thinking, slurred speech, hypertension, urinary retention, livedo reticularis (a skin reaction) and skin rash (Endo Pharmaceuticals Inc., 2007).

References

Green LB, Hornyak JE, Hurvitz EA. Amantadine in pediatric patients with traumatic brain injury: a retrospective, case-controlled study. Am J Phys Med Rehabil. 2004 Dec;83(12):893-7. doi: 10.1097/01.phm.0000143400.15346.c8. PMID: 15624567.

https://pubmed.ncbi.nlm.nih.gov/15624567/

Hosenbocus S, Chahal R. Amantadine: a review of use in child and adolescent psychiatry. J Can Acad Child Adolesc Psychiatry. 2013 Feb;22(1):55-60. PMID: 23390434; PMCID: PMC3565716.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3565716/

McGrane IR, Loveland JG, Zaluski HJ. Adjunctive Amantadine Treatment for Aggressive Behavior in Children: A Series of Eight Cases. J Child Adolesc Psychopharmacol. 2016 Dec;26(10):935-938. doi: 10.1089/cap.2016.0042. Epub 2016 Aug 2. PMID: 27483360.

https://pubmed.ncbi.nlm.nih.gov/27483360/

About this Article

Written by the health professionals at the Children’s Hospital of Eastern Ontario (CHEO) in Ottawa, Ontario, Canada.

Conflicts of interest: The authors have no competing interests to declare.

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Disclaimer

Information in this pamphlet is offered ‘as is' and is meant only to provide general information that supplements, but does not replace the information from your health provider. Always contact a qualified health professional for further information in your specific situation or circumstance.

Date Posted: Sep 14, 2021
Date of Last Revision: Sep 14, 2021

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