Amantadine or ramantadine can be used to prevent influenza A in susceptible persons during times of transmission.
Patients who may benefit from influenza chemoprophylaxis:
(1) unvaccinated persons who are (a) in contact with persons at high risk for influenza complications or (b) persons at high risk for complications who reside in an institutional setting
(2) unvaccinated persons who wish to avoid influenza A
(3) vaccinated persons exposed to influenza before immunity develops (immunity develops about 14 days after immunization)
(4) immune deficient persons who might not develop protective immunity following vaccination
(5) persons with a contraindication to vaccination, usually hypersensitivity to egg products or vaccine components
Patients who would not benefit from influenza chemoprophylaxis
(1) persons exposed to influenza B
(2) persons vaccinated against influenza after immunity develops
Dosages
Age |
Dose of Amantadine |
Dose of Rimantadine |
< 1 year of age |
use not adequately evaluated |
use not adequately evaluated |
1-9 years of age |
5 mg/kg/day up to 150 mg, divided into 2 doses |
5 mg/kg/day up to 150 mg, divided into 2 doses |
10-13 years of age weighing < 40 kg |
5 mg/kg/day up to 150 mg, divided into 2 doses |
5 mg/kg/day up to 150 mg, divided into 2 doses |
10-13 years of age weighing >= 40 kg |
100 mg twice daily |
100 mg twice daily |
14-64 years of age |
100 mg twice daily |
100 mg twice daily |
>= 65 years of age |
<= 100 mg/day |
100 to 200 mg/day |
Special dosage situations:
(1) liver disease
(1a) If the patient has severe liver disease, then reduce dosage of rimantadine to 100 mg/day.
(1b) In patients with moderate liver disease, administer usual dosages but monitor patients closely, being ready to reduce dose to 100 mg/day if adverse effects develop.
(2) kidney disease
(2a) If the creatinine clearance is <= 10 mL/min, then reduce dosage of rimantadine to 100 mg/day. See spreadsheet on amantadine in renal disease (under dosing antibiotics in renal failure).
(2b) In patients with moderate kidney disease, administer usual dosages but monitor patients closely, being ready to reduce dose to 100 mg/day if adverse effects develop.
The incidence of CNS side effects is higher in persons taking amantadine than those taking rimantadine.
Specialty: Infectious Diseases, Pharmacology, clinical