A possible antiviral effect of amantadine in an AH1N1 influenza-infected patient – a case report

Dear Editor,
Acute respiratory infections caused by various viral strains are among the most frequent illnesses across the world [1]. Annual epidemics caused by influenza A viruses are one of the leading factors of morbidity and mortality. Therefore both prophylaxis and antiviral pharmacological treatment are the focal point of many past and ongoing studies.
Amantadine is a tricyclic water soluble amine, a derivative of adamantine. It was the first identified inhibitor of influenza virus that acts by blocking the virus M2 protein ion channel and inhibiting the early stages of virus replication [2]. Historically amantadine played a major role in antiviral treatment and prophylaxis, nowadays reduced due to the emergence of amantadine-resistant influenza strains [3]. The main mechanisms of resistance are based on mutations in the M2 protein that leads to the loss of the possibility of binding or action. Amino acid substitutions in the M2 protein prevent binding to the ion channel or modify its structure to allow it to operate in the presence of an active drug [4]. Most mutations responsible for the drug resistance do not cause deterioration of replicative functions and virulence [5].
In most cases influenza virus infection manifests as an upper airway inflammation, occasionally leading to bronchial hyper-reactivity, distal airway obstruction, impaired diffusion capacity, and severe alveolar inflammation that may cause respiratory failure. Currently treatment of severe influenza disease focuses on prompt antiviral therapy with neuraminidase inhibitors such as oseltamivir or zanamivir due to the fact that most circulating strains are susceptible to these agents. Possible therapeutic interventions also include immunomodulation and extracorporeal membrane oxygenation [6].
Beside its use as an antiviral agent, amantadine is a potent, multipurpose drug used in many clinical settings. Currently the main indications for the use of amantadine are Parkinson’s disease, both in monotherapy and combined with other drugs [7], traumatic brain injury [8], autistic spectrum disorders, attention deficits, hyperactivity disorders, drug-induced extrapyramidal side effects and motor fluctuations during L-DOPA treatment. Current research assesses its use as an antidepressant [9] and antiepileptic drug [10]. Neurological effects are mainly attributed to the impact on the dopaminergic system through enhancement of dopamine release and inhibition of its...


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