An RNA synthesis inhibitor that is used as an antiviral agent in the prophylaxis and treatment of influenza. [PubChem]
Indication
For the prophylaxis and treatment of illness caused by various strains of influenza A virus in adults.
Pharmacology
Rimantadine, a cyclic amine, is a synthetic antiviral drug and a derivate of adamantane, like a similar drug amantadine. Rimantadine is inhibitory to the in vitro replication of influenza A virus isolates from each of the three antigenic subtypes (H1N1, H2H2 and H3N2) that have been isolated from man. Rimantadine has little or no activity against influenza B virus. Rimantadine does not appear to interfere with the immunogenicity of inactivated influenza A vaccine.
Toxicity
Oral LD50 in rats is 640 mg/kg. Overdoses of a related rug, amantadine, have been reported with adverse reactions consisting of agitation, hallucinations, cardiac arrhythmia and death.
Affected Organisms
Human Influenza A Virus
Biotransformation
Following oral administration, rimantadine is extensively metabolized in the liver with less than 25% of the dose excreted in the urine as unchanged drug. Glucuronidation and hydroxylation are the major metabolic pathways.
Absorption
Well absorbed, with the tablet and syrup formulations being equally absorbed after oral administration.
Half Life
25 to 30 hours in young adults (22 to 44 years old). Approximately 32 hours in elderly (71 to 79 years old) and in patients with chronic liver disease. Approximately 13 to 38 hours in children (4 to 8 years old).
Protein Binding
Approximately 40% over typical plasma concentrations.
Elimination
Following oral administration, rimantadine is extensively metabolized in the liver with less than 25% of the dose excreted in the urine as unchanged drug.
