(Amantadine Hydrochloride, USP)
Tablets and Syrup
SYMMETREL (Amantadine Hydrochloride, USP) is designated generically as amantadine hydrochloride and chemically as 1-adamantanamine hydrochloride.
SYMMETREL is indicated for the prophylaxis and treatment of signs and symptoms of infection caused by various strains of influenza A virus. SYMMETREL is also indicated in the treatment of parkinsonism and drug-induced extrapyramidal reactions.
Influenza A Prophylaxis: SYMMETREL (Amantadine Hydrochloride, USP) is indicated for chemoprophylaxis against signs and symptoms of influenza A virus infection when early vaccination is not feasible or when the vaccine is contraindicated or not available. In the prophylaxis of influenza, early vaccination on an annual basis as recommended by the Centers for Disease Control's Immunization Practices Advisory Committee is the method of choice. Because SYMMETREL does not completely prevent the host immune response to influenza A infection, individuals who take this drug may still develop immune responses to natural disease or vaccination and may be protected when later exposed to antigenically related viruses. Following vaccination during an influenza A outbreak, SYMMETREL prophylaxis should be considered for the 2- to 4-week time period required to develop an antibody response.
Influenza A Treatment: SYMMETREL is also indicated in the treatment of uncomplicated respiratory tract illness caused by influenza A virus strains especially when administered early in the course of illness. There are no well-controlled clinical studies demonstrating that treatment with SYMMETREL will avoid the development of influenza A virus pneumonitis or other complications in high risk patients.
There is no clinical evidence indicating that SYMMETREL is effective in the prophylaxis or treatment of viral respiratory tract illnesses other than those caused by influenza A virus strains.
Parkinson's Disease/Syndrome: SYMMETREL is indicated in the treatment of idiopathic Parkinson's disease (Paralysis Agitans), postencephalitic parkinsonism, and symptomatic parkinsonism which may follow injury to the nervous system by carbon monoxide intoxication. It is indicated in those elderly patients believed to develop parkinsonism in association with cerebral arteriosclerosis. In the treatment of Parkinson's disease, SYMMETREL is less effective than levodopa, (-),-3-(3,4-dihydroxyphenyl)-L-alanine, and its efficacy in comparison with the anticholinergic antiparkinson drugs has not yet been established.
Drug-Induced Extrapyramidal Reactions: SYMMETREL is indicated in the treatment of drug-induced extrapyramidal reactions. Although anticholinergic-type side effects have been noted with SYMMETREL when used in patients with drug-induced extrapyramidal reactions, there is a lower incidence of these side effects than that observed with the anticholinergic antiparkinson drugs.
Published Studies Related to Symmetrel (Amantadine)
Double-blind, placebo-controlled trial of risperidone plus amantadine in children
with autism: a 10-week randomized study. 
risperidone for treatment of autism... CONCLUSIONS: The present study suggests that amantadine may be a potential
Assessment of treatment algorithms including amantadine, metformin, and zonisamide for the prevention of weight gain with olanzapine: a randomized controlled open-label study. [2011.05.17]
CONCLUSIONS: Pooled treatment algorithm results were not significantly different from olanzapine monotherapy in mitigating weight gain. However, participants who received treatment with metformin with possible progression to amantadine and then zonisamide had significantly less mean weight gain than participants treated with olanzapine alone. Progression of some participants through the algorithm indicated that a single therapy solution may not be adequate for every patient. Patients treated with olanzapine should receive regular weight monitoring. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00401973. (c) Copyright 2011 Physicians Postgraduate Press, Inc.
Amantadine for dyskinesias in Parkinson's disease: a randomized controlled trial. [2010.12.31]
BACKGROUND: Dyskinesias are some of the major motor complications that impair quality of life for patients with Parkinson's disease. The purpose of the present study was to investigate the efficacy of amantadine in Parkinson's disease patients suffering from dyskinesias... CONCLUSIONS: Results from the present study demonstrated that amantadine exhibited efficacious effects against dyskinesias in 60-70% of patients. TRIAL REGISTRATION: UMIN Clinical Trial Registry UMIN000000780.
Amantadine versus methylphenidate in children and adolescents with attention deficit/hyperactivity disorder: a randomized, double-blind trial. [2010.12.08]
Objective The aim of the present study was to further evaluate, under double blind and controlled conditions, the efficacy of amantadine for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents as compared to methylphenidate.Methods This was a 6-week randomized clinical trial...
Amantadine versus methylphenidate in children and adolescents with attention deficit/hyperactivity disorder: a randomized, double-blind trial. [2010.11]
OBJECTIVE: The aim of the present study was to further evaluate, under double blind and controlled conditions, the efficacy of amantadine for attention-deficit/hyperactivity disorder (ADHD) in children and adolescents as compared to methylphenidate... CONCLUSION: The results of this study indicate that amantadine significantly improved symptoms of ADHD and was well tolerated and it may be beneficial in the treatment of children with ADHD. Nevertheless, the present results do not constitute proof of efficacy. Copyright (c) 2010 John Wiley & Sons, Ltd.
Clinical Trials Related to Symmetrel (Amantadine)
Study of Amantadine for Risperidone Consta or Paliperidone Treated Patients to Decrease Prolactin Elevation [Terminated]
The purpose of this study is to show that amantadine might help to reduce the side effect of
the medications which are prescribed to treat schizophrenia or schizoaffective disorder.
High level of hormone prolactin, or hyperprolactinemia, is one of the side effects which
might be developed in patients treated with the paliperidone ER or risperidone Consta.
High level of prolactin might stimulate breast development, might decrease sexual desire
(libido). The goals of this study are to demonstrate that amantadine lowers prolactin
levels, decreases side effects, and improves psychiatric symptoms.
Amantadine + rTMS as a Neurotherapeutic for Disordered Consciousness [Recruiting]
The purpose of this study is to examine the safety and efficacy of repetitive transcranial
magnetic stimulation (rTMS) combined with Amantadine relative to rTMS Alone and Amantadine
Alone for persons in chronic states of seriously impaired consciousness. The hypothesis is
that provision of rTMS+Amantadine will provide a safe yet synergistic effect that induces or
accelerates functional recovery.
Amantadine to Speed Awakening After Cardiac Arrest [Not yet recruiting]
This study evaluates if amantadine will increase the rate of awakening in patients
resuscitated from cardiac arrest but comatose (not following commands) after their
resuscitation. Half of the participants will receive amantadine and the other will receive
Validation of Dyskinesia Rating Scales [Completed]
This study will evaluate the responsiveness of a variety of available dyskinesia rating
scales to treatment with amantadine or placebo in Parkinson's disease patients with
dyskinesia. The study will be a parallel, double-blind, randomized trial of 68 patients
treated with amantadine or placebo for 8 weeks. Pre-treatment evaluations will be performed
and compared to end of study evaluations on the best treatment dose (200 or 300 mg
amantadine or matching placebo) daily. Safety evaluations will be conducted.
The responsiveness of the different scales will be evaluated statistically with a mixed
model in which changes in the outcome measures over time will include a fixed effect of
treatment group assignment. The model will additionally account for random effects of
intercepts (the scale scores at baseline) that will include both random variation
(person-specific) and specific variation associated with rate of change in outcome. The
investigators may include adjustments for possible confounding covariates, including
baseline demographics and center. The goal of the program is to provide researchers with
the best scale(s) to distinguish dyskinesia change in Parkinson's disease (PD) associated
with amantadine in comparison to placebo and to establish the magnitude of effect achievable
with amantadine as a comparator "gold standard" that must be met or surpassed by future
anti-dyskinetic agents. Additionally, with the use of paper and pencil questionnaires, the
study will investigate the impact of patient optimism and patient and rater expectation of
positive effects on the dyskinesia rating outcomes.
Effectiveness of Amantadine Hydrochloride for Treatment of Severe Traumatic Brain Injury (TBI) [Completed]
This is a controlled trial of amantadine to improve level of function following severe
traumatic brain injury.
The purpose of this study is:
1. To determine whether amantadine hydrochloride, given in a dose of 200-400 mg, improves
functional recovery from the vegetative and minimally conscious states
2. To determine whether amantadine-related gains in function persist following drug
3. To determine the safety profile of amantadine in patients with disorders of
Reports of Suspected Symmetrel (Amantadine) Side Effects
Atrioventricular Block Complete (4),
Psychiatric Symptom (4),
Neuroleptic Malignant Syndrome (4),
Altered State of Consciousness (4),
Penile Size Reduced (3),
Ventricular Hypertrophy (3),
Ileus (3), more >>
Page last updated: 2014-11-30