Amantadine Dosage

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Usual Adult Dose for:

Usual Geriatric Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Influenza Prophylaxis

Normally recommended dose: 200 mg orally per day in 1 to 2 divided doses

Comments:
-Twice-daily dosing may minimize central nervous system (CNS) side effects.
-In healthy adults not at risk for influenza-related complications, 100 mg per day may be effective for prophylaxis; not known if 100 mg/day is as effective as 200 mg/day.
-For patients with intolerance to 200 mg/day due to CNS or other toxicities, 100 mg/day is recommended.

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Usual Adult Dose for Influenza A

Normally recommended dose: 200 mg orally per day in 1 to 2 divided doses

Comments:
-Twice-daily dosing may minimize central nervous system (CNS) side effects.
-In healthy adults not at risk for influenza-related complications, 100 mg per day may be effective for prophylaxis; not known if 100 mg/day is as effective as 200 mg/day.
-For patients with intolerance to 200 mg/day due to CNS or other toxicities, 100 mg/day is recommended.

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Usual Adult Dose for Parkinson's Disease

Monotherapy:
100 mg orally twice a day; onset usually within 48 hours

In patients with serious associated medical illnesses or receiving high doses of other antiparkinson drugs:
Initial dose: 100 mg once a day
After 1 to several weeks at initial dose: The dose may be increased to 100 mg orally twice a day, if needed.

Comments:
-Patients whose responses are not optimal at 200 mg/day may benefit from an increase up to 400 mg per day in divided doses; close supervision recommended.
-Amantadine's efficacy can wane after a few months. If patient is not at maximum tolerated dose, increasing dose may help. Alternatively, temporary discontinuation of drug for several weeks may help to recover some of the drug's effects when it is reinstated. The use of other antiparkinson drugs may be necessary.

Concomitant therapy:
-When amantadine and levodopa are started concurrently, rapid therapeutic benefits may occur. Amantadine dose should remain constant at 100 mg orally once or twice a day while the daily dose of levodopa is gradually increased to optimal benefit.
-Additional benefit may result from adding amantadine to optimal well-tolerated doses of levodopa; such benefit includes smoothing out improvement fluctuations that can occur with levodopa alone. Patients who reduce levodopa dose due to side effects may regain lost benefit with the addition of amantadine.

Approved indication: For treatment of parkinsonism

Usual Adult Dose for Extrapyramidal Reaction

100 mg orally twice a day

Comments:
-Patients whose responses are not optimal at 200 mg/day may benefit from an increase up to 300 mg per day in divided doses.

Approved indication: For treatment of drug-induced extrapyramidal reactions

Usual Geriatric Dose for Influenza Prophylaxis

Normally recommended dose:
65 years or older: 100 mg orally per day

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Usual Geriatric Dose for Influenza A

Normally recommended dose:
65 years or older: 100 mg orally per day

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Usual Pediatric Dose for Influenza Prophylaxis

Normally recommended doses:
1 to 9 years: 4.4 to 8.8 mg/kg orally per day; not to exceed 150 mg/day
10 to 12 years: 100 mg orally twice a day

Advisory Committee on Immunization Practices (ACIP) and American Academy of Pediatrics (AAP) recommendations (to reduce risk for toxicity):
1 to 9 years: 5 mg/kg orally per day in 2 divided doses; not to exceed 150 mg/day
10 years or older, less than 40 kg: 5 mg/kg orally per day
10 years or older, 40 kg or more: 100 mg orally twice a day

Alternative prophylactic dose for children weighing more than 20 kg: 100 mg per day

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Usual Pediatric Dose for Influenza A

Normally recommended doses:
1 to 9 years: 4.4 to 8.8 mg/kg orally per day; not to exceed 150 mg/day
10 to 12 years: 100 mg orally twice a day

Advisory Committee on Immunization Practices (ACIP) and American Academy of Pediatrics (AAP) recommendations (to reduce risk for toxicity):
1 to 9 years: 5 mg/kg orally per day in 2 divided doses; not to exceed 150 mg/day
10 years or older, less than 40 kg: 5 mg/kg orally per day
10 years or older, 40 kg or more: 100 mg orally twice a day

Alternative prophylactic dose for children weighing more than 20 kg: 100 mg per day

Approved indications: For treatment of uncomplicated respiratory tract illness due to influenza A virus strains, especially when used early in course of illness; for chemoprophylaxis against signs/symptoms of influenza A virus infection

Renal Dose Adjustments

CrCl 30 to 50 mL/min: 200 mg orally the first day and 100 mg each day thereafter
CrCl 15 to 29 mL/min: 200 mg orally the first day followed by 100 mg on alternate days
CrCl less than 15 mL/min: 200 mg orally every 7 days

Liver Dose Adjustments

Caution recommended.

Dose Adjustments

The dose may require careful adjustment in patients with congestive heart failure, peripheral edema, or orthostatic hypotension.

Precautions

Consult WARNINGS section for dosing related precautions.

Dialysis

Hemodialysis: 200 mg orally every 7 days

Comments:
-Amantadine is not significantly removed by hemodialysis; supplementary dosing not required after hemodialysis.

Other Comments

On the basis of available antiviral testing results, the Centers for Disease Control and Prevention (CDC) recommends that amantadine not be used for treatment or prophylaxis of currently circulating influenza A virus strains; oseltamivir or zanamivir recommended if antiviral medication needed.

Administration advice for treatment of influenza A:
-Therapy should start as soon as possible, preferably within 24 to 48 hours after onset of signs/symptoms.
-Therapy should continue for 24 to 48 hours after signs/symptoms disappear.

Administration advice for influenza prophylaxis:
-Therapy should be started in anticipation of an outbreak and before or after contact with individuals with influenza A virus respiratory tract illness.
-Amantadine should be continued for at least 10 days after known exposure.
-If used in conjunction with inactivated influenza A virus vaccine until protective antibody responses develop, amantadine should be used for 2 to 4 weeks after vaccine has been given; children receiving influenza virus vaccine for the first time may require amantadine prophylaxis for up to 6 weeks after vaccination or 2 weeks after the second dose of vaccine.
-For maximal efficacy in an outbreak, therapy should continue for the entire duration of influenza activity in the community, or at least during peak influenza activity if cost is a concern.

General:
-Annual vaccination is preferred method for prophylaxis against influenza A; amantadine should not be considered a substitute.
-Influenza-like illnesses are caused by many different viruses. The activity of amantadine is limited to influenza A.

Patient advice:
-Patients should be informed that treatment with amantadine has not been shown to reduce the risk of transmission of influenza to others and to avoid contact with uninfected persons as much as possible.

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