Amantadine

What is Amantadine?

• Amantadine (Gocovri; Osmolex ER; Symadine; Symmetrel), a synthetic tricyclic amine with antiviral, antiparkinsonian, and antihyperalgesic activities.

Amantadine

Amantadine ball-and-stick model

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What are the uses of this medicine?

• Amantadine (Gocovri; Osmolex ER; Symadine; Symmetrel) is used for the prophylaxis and treatment of signs and symptoms of infection caused by various strains of influenza A virus.
• Amantadine hydrochloride tablets are also indicated in the treatment of parkinsonism and drug-induced extrapyramidal reactions.

Influenza A Prophylaxis:

• Amantadine hydrochloride tablets are indicated for chemoprophylaxis against signs and symptoms of influenza A virus infection.

Influenza A Treatment:

• Amantadine hydrochloride tablets are 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.

Parkinson's Disease / Syndrome:

• Amantadine hydrochloride tablets are 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

Drug-Induced Extrapyramidal Reactions:

• Amantadine hydrochloride tablets are indicated in the treatment of drug-induced extrapyramidal reactions.

How does this medicine work?

• The hydrochloride salt of amantadine, a synthetic tricyclic amine with antiviral, antiparkinsonian, and antihyperalgesic activities.
• Amantadine appears to exert its antiviral effect against the influenza A virus by interfering with the function of the transmembrane domain of the viral M2 protein, thereby preventing the release of infectious viral nucleic acids into host cells; furthermore, this agent prevents virus assembly during virus replication.
• Amantadine exerts its antiparkinsonian effects by stimulating the release of dopamine from striatal dopaminergic nerve terminals and inhibiting its pre-synaptic reuptake.
• This agent may also exert some anticholinergic effect through inhibition of N-methyl-D-aspartic acid (NMDA) receptor-mediated stimulation of acetylcholine, resulting in antihyperalgesia.

Who Should Not Use this medicine ?

This medicine cannot be used in patients with:

• hypersensitivity to amantadine hydrochloride or to any of the other ingredients in amantadine hydrochloride tablets.

What drug interactions can this medicine cause?

• Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

Be sure to mention any of the following:

• acetazolamide
• antihistamines
• dichlorphenamide
• hydrochlorothiazide with triamterene (Maxzide, Dyrenium)
• medications for mental illness, motion sickness, sleep, or urinary problems
• other medications to treat Parkinson's disease
• methazolamide
• quinine (Qualaquin)
• quinidine (in Nuedexta)
• sedatives
• sodium bicarbonate (Alka-Seltzer, in Zegerid)
• stimulants
• thioridazine

Is this medicine FDA approved?

• 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.
• In 1973, the Food and Drug Administration (FDA) approved amantadine for use in the treatment of Parkinson's disease.
• In 2017, the extended release formulation was approved for use in the treatment of levodopa-induced dyskinesia.

How should this medicine be used?

Recommended dosage:

Dosage for Prophylaxis and Treatment of Uncomplicated Influenza A Virus Illness: In Adults:

• The adult daily dosage of amantadine hydrochloride tablets is 200 mg; two 100 mg tablets as a single daily dose.

In Pediatric Patients: 1 yr. to 9 yrs. of age:

• The total daily dose should be calculated on the basis of 2 to 4 mg/lb/day (4.4 to 8.8 mg/kg/day), but not to exceed 150 mg per day.

9 yrs. to 12 yrs. of age:

• The total daily dose is 200 mg given as one tablet of 100 mg twice a day.

Dosage for Parkinsonism: In Adults:

• The usual dose of amantadine hydrochloride tablets is 100 mg twice a day when used alone.
• Amantadine hydrochloride tablets have an onset of action usually within 48 hours.
• The initial dose of amantadine hydrochloride tablets is 100 mg daily for patients with serious associated medical illnesses or who are receiving high doses of other antiparkinson drugs.
• After one to several weeks at 100 mg once daily, the dose may be increased to 100 mg twice daily, if necessary.

Dosage for the Concomitant Therapy:

• When amantadine hydrochloride tablets and levodopa are initiated concurrently, the patient can exhibit rapid therapeutic benefits.
• Amantadine hydrochloride tablets should be held constant at 100 mg daily or twice daily while the daily dose of levodopa is gradually increased to optimal benefit.

Dosage for Drug-Induced Extrapyramidal Reactions: In Adults:

• The usual dose of amantadine hydrochloride tablets is 100 mg twice a day.

Administration:

• Amantadine comes as a capsule, extended-release capsule (Gocovri), tablet, extended-release tablet (Osmolex), and liquid to take by mouth.
• The capsules, tablets, and liquid medications are usually taken once or twice a day. The extended-release capsules are usually taken once a day at bedtime.
• The extended-release tablets are usually taken once a day in the morning.
• Take amantadine at around the same time every day.
• Swallow the extended-release capsules and extended-release tablets whole; do not split, chew, or crush them.
• If you have difficulty swallowing the extended-release capsule, you may open the capsule and sprinkle the entire contents on a teaspoonful of soft food, like applesauce.
• Eat the mixture right away and swallow without chewing.
• If you are taking amantadine for Parkinson's disease, your doctor may start you on a low dose of amantadine and gradually increase your dose.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As a capsule, extended-release capsule (Gocovri), tablet, extended-release tablet (Osmolex), and liquid

This medicine is available in fallowing brand namesː

• Gocovri; Osmolex ER; Symadine; Symmetrel

What side effects can this medication cause?

The most common side effects of this medicine include:

• nausea, dizziness (lightheadedness),insomnia, depression, anxiety and irritability, hallucinations, confusion, anorexia, dry mouth, constipation, ataxia, livedo reticularis, peripheral edema, orthostatic hypotension, headache, somnolence, nervousness, dream abnormality, agitation, dry nose, diarrhea, and fatigue

Less common, but serious side effects may include: congestive heart failure, psychosis, urinary retention, dyspnea, skin rash, vomiting, weakness, slurred speech, euphoria, thinking abnormality, amnesia, hyperkinesia, hypertension, decreased libido, and visual disturbance, including punctate subepithelial or other corneal opacity, corneal [[]]edema, decreased visual acuity, sensitivity to light, optic nerve palsy, instances of convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide, and suicidal ideation.

What special precautions should I follow?

• Suicide attempts, some of which have been fatal, have been reported in patients treated with amantadine hydrochloride, many of whom received short courses for influenza treatment or prophylaxis. Patients who attempt suicide may exhibit abnormal mental states which include disorientation, confusion, depression, personality changes, agitation, aggressive behavior, hallucinations, paranoia, other psychotic reactions, and somnolence or insomnia.
• Because of the possibility of serious adverse effects, caution should be observed when prescribing amantadine hydrochloride tablets to patients being treated with drugs having CNS effects, or for whom the potential risks outweigh the benefit of treatment.
• Patients with a history of epilepsy or other "seizures" should be observed closely for possible increased seizure activity.
• Patients receiving amantadine hydrochloride tablets who note central nervous system effects or blurring of vision should be cautioned against driving or working in situations where alertness and adequate motor coordination are important.
• Patients with Parkinson's disease improving on amantadine hydrochloride tablets should resume normal activities gradually and cautiously, consistent with other medical considerations, such as the presence of osteoporosis or phlebothrombosis.
• Because amantadine hydrochloride tablets have anticholinergic effects and may cause mydriasis, it should not be given to patients with untreated angle closure glaucoma.
• Amantadine hydrochloride should not be discontinued abruptly in patients with Parkinson's disease. Abrupt discontinuation may also precipitate delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression, and slurred speech.
• Neuroleptic Malignant Syndrome (NMS) have been reported in association with dose reduction or withdrawal of amantadine hydrochloride therapy. Therefore, patients should be observed carefully when the dosage of amantadine hydrochloride is reduced abruptly or discontinued, especially if the patient is receiving neuroleptics.
• The dose of amantadine hydrochloride should be reduced in patients with renal impairment and in individuals who are 65 years of age or older.
• Care should be exercised when administering amantadine hydrochloride to patients with liver disease.
• Patients treated with anti-Parkinson medications can experience intense urges to gamble, increased sexual urges, intense urges to spend money uncontrollably, and other intense urges. Physicians should consider dose reduction or stopping the medication if a patient develops such urges while taking amantadine hydrochloride.
• The dose of amantadine hydrochloride may need careful adjustment in patients with congestive heart failure, peripheral edema, or orthostatic hypotension.
• Avoid excessive alcohol usage, since it may increase the potential for CNS effects such as dizziness, confusion, lightheadedness, and orthostatic hypotension.
• Avoid getting up suddenly from a sitting or lying position. If dizziness or lightheadedness occurs, notify physician.
• Notify physician if mood/mental changes, swelling of extremities, difficulty urinating and/or shortness of breath occur.
• Do not take more medication than prescribed because of the risk of overdose. If there is no improvement in a few days, or if medication appears less effective after a few weeks, discuss with a physician.
• Consult physician before discontinuing medication.

What to do in case of emergency/overdose?

Symptoms of overdose may include:

• irregular or fast heartbeat
• difficulty breathing
• decreased urination
• swelling of the hands, feet, ankles or lower legs
• stiff or rigid arms or legs
• uncontrollable movements or shaking of a part of the body
• problems with coordination
• confusion
• feeling like you are looking at yourself as an outside observer
• fear, irritability, or aggressive behavior
• seeing things or hearing voices that do not exist
• lack of energy

Management of overdosage:

• In case of overdose, call the poison control helpline of your country. In the United States, call 1-800-222-1222.

• Overdose related information is also available online at poisonhelp.org/help.
• In the event that the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services. In the United States, call 911.
• There is no specific antidote for an overdose of amantadine hydrochloride.
• However, slowly administered intravenous physostigmine in adult and children have been reported to be effective in the control of central nervous system toxicity caused by amantadine hydrochloride.
• For acute overdosing, general supportive measures should be employed along with immediate gastric lavage or induction of emesis. Fluids should be forced, and if necessary, given intravenously.
• Since the excretion rate of amantadine hydrochloride increases rapidly when the urine is acidic, the administration of urine acidifying drugs may increase the elimination of the drug from the body.
• The blood pressure, pulse, respiration and temperature should be monitored.
• The patient should be observed for hyperactivity and convulsions; if required, sedation, and anticonvulsant therapy should be administered.
• The patient should be observed for the possible development of arrhythmias and hypotension; if required, appropriate antiarrhythmic and antihypotensive therapy should be given.
• Electrocardiographic monitoring may be required after ingestion, since malignant tachyarrhythmias can appear after overdose.
• The blood electrolytes, urine pH and urinary output should be monitored.
• If there is no record of recent voiding, catheterization should be done.

Can this medicine be used in pregnancy?

• Amantadine hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the embryo or fetus.

Can this medicine be used in children?

• The safety and efficacy of amantadine hydrochloride in newborn infants and infants below the age of 1 year have not been established.

What are the active and inactive ingredients in this medicine?

Active ingredient:

• amantadine hydrochloride

Inactive ingredients:

• fd&c yellow no. 6
• aluminum oxide
• silicon dioxide
• magnesium stearate
• povidone, unspecified
• microcrystalline cellulose
• starch, potato

Who manufactures and distributes this medicine?

Manufactured by:

• upsher-smith laboratories, llc.
• Maple Grove, MN.

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F).
• Protect from light and moisture.
• Dispense in a tight, light-resistant container as defined in the USP, with child-resistant closure.

• Dailymed label info on Amantadine
• FDA Amantadine

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