What is the indication for rimantadine (antiviral medication) in adults and children?

Indications for Rimantadine

Rimantadine is indicated for prophylaxis of influenza A in adults (≥17 years) and children (1-16 years), and for treatment of influenza A illness in adults only (≥17 years), with therapy initiated within 48 hours of symptom onset. 1

FDA-Approved Indications

Treatment

• Adults (≥17 years): Rimantadine is approved for treatment of influenza A illness when administered within 48 hours of symptom onset, reducing duration of fever and systemic symptoms 1
• Children (≤16 years): Rimantadine is NOT indicated for treatment in pediatric patients 16 years or younger 1
  • Note: Some influenza specialists consider rimantadine appropriate for treatment in children despite lack of FDA approval for this indication 2

Prophylaxis

• Adults (≥17 years): Approved for prophylaxis against influenza A virus, with 70-90% effectiveness in preventing illness 2, 1
• Children (1-16 years): Approved for prophylaxis only, not treatment 1
• Infants (<1 year): Safety and efficacy have not been established 1

Mechanism and Spectrum of Activity

• Rimantadine interferes with the replication cycle of influenza A viruses only—it has NO activity against influenza B 2
• When used prophylactically, rimantadine prevents clinical illness but not subclinical infection, allowing development of protective antibodies 2

Clinical Scenarios for Use

Prophylaxis Indications

High-risk patients vaccinated after influenza A activity has begun:

• Adults require 2 weeks of chemoprophylaxis after vaccination for antibody development 2
• Children receiving influenza vaccine for the first time require up to 6 weeks of prophylaxis (2 weeks after the second vaccine dose) 2
• Rimantadine does not interfere with antibody response to vaccine 2

Healthcare workers and caregivers:

• Unvaccinated persons with frequent contact with high-risk individuals (household members, visiting nurses, hospital/nursing home staff) during community outbreaks 2
• Consider for all employees regardless of vaccination status if outbreak caused by vaccine-mismatched strain 2

Institutional outbreak control:

• Nursing homes: Initiate chemoprophylaxis for all residents (vaccinated and unvaccinated) when influenza A identified, continuing until approximately 1 week after outbreak ends 2
• Successfully used to control influenza A outbreaks in closed settings including cruise ships 2

Treatment Indications

Adults with influenza-like illness:

• Therapy should be initiated within 48 hours of symptom onset during known or suspected influenza A activity in the community 2, 1
• Continue treatment for approximately 7 days from initial symptom onset 1
• Reduces duration of fever and systemic symptoms by 1-3 days compared to placebo 3, 4

Critical Limitations and Caveats

Rimantadine is NOT a substitute for annual influenza vaccination 1

Drug resistance concerns:

• Resistant virus can emerge as early as 2 days after starting treatment, occurring in up to 33% of treated patients 4
• During institutional outbreaks, minimize contact between persons receiving treatment and those receiving prophylaxis to limit transmission of resistant virus 2
• Prescribers should consider available surveillance data on drug susceptibility patterns before prescribing 1

Efficacy limitations:

• Not demonstrated to prevent serious influenza-related complications (bacterial/viral pneumonia, exacerbation of chronic diseases) 2
• Prophylaxis effectiveness not demonstrated beyond 6 weeks duration 1
• Symptom reduction differences between rimantadine and placebo after first 3 days generally not clinically significant 3

Timing considerations:

• For prophylaxis to be maximally effective, must be taken daily throughout influenza activity period in the community 2
• Most cost-effective approach: use only during peak influenza activity period 2