Amantadine Hcl

(Amantadine Hydrochloride)

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Amantadine Hcl Prescribing Information

Amantadine Hydrochloride Capsules, USP are indicated for the prophylaxis and treatment of signs and symptoms of infection caused by various strains of influenza A virus. Amantadine Hydrochloride Capsules, USP are also indicated in the treatment of parkinsonism and drug-induced extrapyramidal reactions.

Influenza A Prophylaxis:

Amantadine Hydrochloride Capsules, USP are indicated for chemoprophylaxis against signs and symptoms of influenza A virus infection. Because Amantadine Hydrochloride 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, Amantadine Hydrochloride Capsules, USP prophylaxis should be considered for the 2- to 4-week time period required to develop an antibody response.

Influenza A Treatment:

Amantadine Hydrochloride Capsules, USP 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. There are no well-controlled clinical studies demonstrating that treatment with Amantadine Hydrochloride Capsules, USP will avoid the development of influenza A virus pneumonitis or other complications in high risk patients.

There is no clinical evidence indicating that Amantadine Hydrochloride Capsules, USP are effective in the prophylaxis or treatment of viral respiratory tract illnesses other than those caused by influenza A virus strains.

The following points should be considered before initiating treatment or prophylaxis with Amantadine Hydrochloride Capsules, USP:

Amantadine Hydrochloride Capsules, USP is not a substitute for early vaccination on an annual basis as recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices.
Influenza viruses change over time. Emergence of resistance mutations could decrease drug effectiveness. Other factors (for example, changes in viral virulence) might also diminish clinical benefit of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use Amantadine Hydrochloride Capsules, USP.

Parkinson's Disease/Syndrome:

Amantadine Hydrochloride Capsules, USP 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. In the treatment of Parkinson's disease, Amantadine Hydrochloride Capsules, USP are 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:

Amantadine Hydrochloride Capsules, USP are indicated in the treatment of drug-induced extrapyramidal reactions. Although anticholinergic-type side effects have been noted with Amantadine Hydrochloride Capsules, USP 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.

The dosage of Amantadine Hydrochloride Capsules may need to be reduced in patients with congestive heart failure, peripheral edema, orthostatic hypotension, or impaired renal function (see

Dosage for Impaired Renal Function:

Depending upon creatinine clearance, the following dosage adjustments are recommended:

CREATININE CLEARANCE (mL/min/1.73 m²)	Amantadine Hydrochloride Capsules, USP DOSAGE
30 to 50	200 mg 1st day and 100 mg each day thereafter
15 to 29	200 mg 1st day followed by 100 mg on alternate days
< 15	200 mg every 7 days

The recommended dosage for patients on hemodialysis is 200 mg every 7 days.

The adverse reactions reported most frequently at the recommended dose of amantadine hydrochloride (5 to 10%) are: nausea, dizziness (lightheadedness), and insomnia.

Less frequently (1 to 5%) reported adverse reactions are: 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.

Infrequently (0.1 to 1%) occurring adverse reactions are: 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, and optic nerve palsy.

Rare (less than 0.1%) occurring adverse reactions are: instances of convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide, and suicidal ideation (see

WARNINGS

Deaths:

Deaths have been reported from overdose with amantadine hydrochloride. The lowest reported acute lethal dose was 1 gram. Acute toxicity may be attributable to the anticholinergic effects of amantadine. Drug overdose has resulted in cardiac, respiratory, renal or central nervous system toxicity. Cardiac dysfunction includes arrhythmia, tachycardia and hypertension (see

OVERDOSAGE

Deaths due to drug accumulation (overdose) have been reported in patients with renal impairment, who were prescribed higher than recommended doses of SYMMETREL (amantadine) for their level of renal function (see

DOSAGE AND ADMINISTRATION; Dosage of Impaired Renal Functionand

OVERDOSAGE

Suicide Attempts:

Suicide attempts, some of which have been fatal, have been reported in patients treated with amantadine, many of whom received short courses for influenza treatment or prophylaxis. The incidence of suicide attempts is not known and the pathophysiologic mechanism is not understood. Suicide attempts and suicidal ideation have been reported in patients with and without prior history of psychiatric illness. Amantadine can exacerbate mental problems in patients with a history of psychiatric disorders or substance abuse. 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 capsules to patients being treated with drugs having CNS effects, or for whom the potential risks outweigh the benefit of treatment.

CNS Effects:

Patients with a history of epilepsy or other "seizures" should be observed closely for possible increased seizure activity.

Patients receiving amantadine hydrochloride capsules 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.

Other:

Patients with a history of congestive heart failure or peripheral edema should be followed closely as there are patients who developed congestive heart failure while receiving amantadine hydrochloride capsules.

Patients with Parkinson's disease improving on amantadine hydrochloride capsules should resume normal activities gradually and cautiously, consistent with other medical considerations, such as the presence of osteoporosis or phlebothrombosis.

Because Amantadine Hydrochloride Capsules has anticholinergic effects and may cause mydriasis, it should not be given to patients with untreated angle closure glaucoma.

Corneal Edema:

Corneal edema has been reported in patients taking amantadine. Symptoms include sudden onset of blurry vision, or progressive vision loss, with or without eye pain. Corneal involvement is usually bilateral. Onset can occur from a few weeks to several years after starting amantadine. Resolution of symptoms typically begins within weeks of amantadine cessation. However, corneal grafts have been required in some patients when the condition is not recognized. Permanent damage can occur if amantadine is continued. Ask patients if their vision has changed and obtain ophthalmologic examinations to rule out corneal edema should vision changes occur after initiation of therapy with amantadine. If corneal edema occurs, taper and discontinue amantadine (see

Dosage and Administration

Drug Interactions:

Careful observation is required when amantadine hydrochloride is administered concurrently with central nervous system stimulants.

Agents with anticholinergic properties may potentiate the anticholinergic-like side effects of amantadine.

Coadministration of thioridazine has been reported to worsen the tremor in elderly patients with Parkinson's disease, however, it is not known if other phenothiazines produce a similar response.

Coadministration of Dyazide
^®(triamterene/hydrochlorothiazide) resulted in a higher plasma amantadine concentration in a 61-year-old man receiving amantadine hydrochloride 100 mg TID for Parkinson's disease.
¹It is not known which of the components of Dyazide
^®contributed to the observation or if related drugs produce a similar response.

Coadministration of quinine or quinidine with amantadine was shown to reduce the renal clearance of amantadine by about 30%.

The concurrent use of amantadine hydrochloride with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of amantadine hydrochloride, unless medically indicated. The concern about possible interference arises from the potential for antiviral drugs to inhibit replication of live vaccine virus. Trivalent inactivated influenza vaccine can be administered at any time relative to use of amantadine.

Amantadine hydrochloride, USP is designated chemically as 1-adamantanamine hydrochloride.

Referenced Image

Amantadine hydrochloride is a stable white or nearly white crystalline powder, freely soluble in water and soluble in alcohol and in chloroform.

Amantadine hydrochloride has pharmacological actions as both an anti-Parkinson and an antiviral drug.

Each capsule intended for oral administration contains 100 mg amantadine hydrochloride and has the following inactive ingredients: yellow iron oxide, gelatin, glycerin, hydrogenated vegetable oil, lecithin-bleached, soybean oil, sorbitol, sorbitan, mannitol, titanium dioxide, white beeswax, vegetable shortening, simethicone and iron oxide (black imprint ink).

USP Dissolution Test Pending.

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Amantadine Hcl

Amantadine Hcl Prescribing Information

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