Amantadine Hydrochloride (5 brand names, 5 dosage forms, 1 route)
Available dosage forms: TABLET, CAPSULE, SYRUP, TABLET, EXTENDED RELEASE, CAPSULE, EXTENDED RELEASE.
Routes of administration: ORAL.
Brand Names
- AMANTADINE HYDROCHLORIDE
- GOCOVRI
- OSMOLEX ER
- SYMADINE
- SYMMETREL
Indications and Usage
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.
Dosage and Administration
The dose of amantadine hydrochloride capsules may need reduction in patients with congestive heart failure, peripheral edema, orthostatic hypotension, or impaired renal function ( see Dosage for Impaired Renal Function).
Contraindications
Amantadine hydrochloride capsules, USP are contraindicated in patients with known hypersensitivity to amantadine hydrochloride or to any of the other ingredients in amantadine hydrochloride capsules, USP.
Adverse Reactions
The adverse reactions reported most frequently at the recommended dose of amantadine (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). Other adverse reactions reported during postmarketing experience with amantadine usage include: Nervous System/Psychiatric coma, stupor, delirium, hypokinesia, hypertonia, delusions, aggressive behavior, paranoid reaction, manic reaction, involuntary muscle contractions, gait abnormalities, paresthesia, EEG changes, and tremor. Abrupt discontinuation may also precipitate delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression and slurred speech; Cardiovascular cardiac arrest, arrhythmias including malignant arrhythmias, hypotension, and tachycardia; Respiratory acute respiratory failure, pulmonary edema, and tachypnea; Gastrointestinal dysphagia; Hematologic leukocytosis, agranulocytosis; Special Senses Keratitis, mydriasis, and corneal edema; Skin and Appendages pruritus and diaphoresis; Miscellaneous neuroleptic malignant syndrom
Drug Interactions
Careful observation is required when amantadine 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 triamterene and hydrochlorothiazide capsules resulted in a higher plasma amantadine concentration in a 61-year-old man receiving amantadine (hydrochloride capsules) 100 mg t.i.d. for Parkinson’s disease 1. It is not known which of the components of triamterene and hydrochlorothiazide capsules 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 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, 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.
Overdosage
Deaths have been reported from overdose with amantadine. The lowest reported acute lethal dose was 1 gram. Because some patients have attempted suicide by overdosing with amantadine, prescriptions should be written for the smallest quantity consistent with good patient management. 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. Pulmonary edema and respiratory distress (including adult respiratory distress syndrome – ARDS) have been reported; renal dysfunction including increased BUN, decreased creatinine clearance and renal insufficiency can occur. Central nervous system effects that have been reported include insomnia, anxiety, agitation, aggressive behavior, hypertonia, hyperkinesia, ataxia, gait abnormality, tremor, confusion, disorientation, depersonalization, fear, delirium, hallucinations, psychotic reactions, lethargy, somnolence and coma. Seizures may be exacerbated in patients with prior history of seizure disorders. Hyperthermia has also been observed in cases where a drug overdose has occurred. There is no specific antidote for an overdose of amantadine. However, slowly administered intravenous physostigmine in 1 and 2 mg doses in an adult 2at 1- to 2-hour intervals and 0.5 mg doses in a child 3at 5- to 10-minute intervals up to a maximum of 2 mg/hour 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. The pH of the urine has been reported to influence the excretion rate of amantadine. Since the excretion rate of amantadine increases rapidly when the urine is acidic, the administration of urine acidifyin