Rimantadine Hydrochloride

Pronunciation: ri-MAN-ta-deen HYE-droe-KLOR-ide
Class: Antiviral agent

Trade Names

Flumadine
- Tablets 100 mg

Pharmacology

Inhibits viral replication cycle in various strains of influenza A virus.

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Pharmacokinetics

Absorption

Well absorbed. C _max is 74 ng/mL (single dose). T _max is 6 h (single dose).

Distribution

Protein binding is 40%, mainly albumin.

Metabolism

Extensively metabolized in the liver to 3 hydroxylated metabolites.

Elimination

Eliminated in the urine (less than 25% as unchanged drug). Half-life is 25.4 h (single dose).

Special Populations

C _max , AUC _{0 to Tau} , and half-life increased by 75%, 81%, and 49%, respectively, in patients with severe renal impairment (CrCl 5 to 29 mL/min). There was a 1.6-fold increase in half-life and 40% decrease in apparent Cl of rimantadine in hemodialysis patients. Half-life was slightly prolonged (increased 18% or less) and there was no clinically relevant difference in C _max and AUC in patients with mild or moderate renal impairment.

AUC was about 3-fold larger, elimination half-life was about 2-fold longer, and apparent Cl was 50% lower in patients with severe hepatic impairment.

In patients older than 70 years of age, the average AUC, peak concentrations, and elimination half-life at steady state were 20% to 30% higher.

Pharmacokinetic profile in children not established.

Indications and Usage

Prophylaxis and treatment of infection caused by various strains of influenza A virus.

Prophylaxis against influenza A virus.

Per the CDC recommendations for treatment and chemoprophylaxis of H1N1 influenza A (swine flu) virus infection, refer to the oseltamivir and zanamivir summary monographs. The H1N1 virus is resistant to the antiviral medication rimantadine. For more information, refer to the CDC guidelines at http://www.cdc.gov/h1n1flu/recommendations.htm .

Unlabeled Uses

Treatment of influenza A virus in children.

Contraindications

Hypersensitivity to drugs in adamantine class, including rimantadine and amantadine.

Dosage and Administration

PO 100 mg twice daily. For the treatment of influenza A, initiate treatment as soon as possible, preferably within 48 h after onset of signs and symptoms of influenza A infection, and continue for approximately 7 days after initial onset of symptoms.

100 mg/day.

PO 100 mg twice daily.

PO 5 mg/kg once daily (max, 150 mg).

General Advice

• An oral suspension (10 mg/mL) may be compounded from the oral tablets using Ora-Sweet for patients who have difficulty swallowing tablets or when a dose lower than 100 mg is needed (see manufacturer's prescribing information for further directions).

Storage/Stability

Store between 59° and 86°F. Compounded oral suspension is stable for 14 days at ambient room temperature.

Drug Interactions

Decreased C _max and AUC of rimantadine. However, based on the magnitude of the interaction, a clinically important consequence is unlikely.

Increased rimantadine serum concentration caused by decreased Cl. However, based on the magnitude of the interaction, a clinically important consequence is unlikely.

Because of potential interference between these products, do not give live attenuated intranasal influenza vaccine until 48 h after cessation of rimantadine, and do not administer rimantadine until 14 days after cessation of live attenuated intranasal influenza vaccine.

Adverse Reactions

CNS

Insomnia (3%); dizziness, impaired concentration, nervousness (2%); asthenia, fatigue, headache (1%).

GI

Nausea (3%); anorexia, dry mouth, vomiting (2%); abdominal pain (1%).

Precautions

Pregnancy

Category C .

Lactation

Undetermined. Do not administer to breast-feeding mothers.

Children

Prophylaxis studies have not been performed in children younger than 1 y of age. Safety and effectiveness for the treatment of symptomatic influenza infection have not been established in children younger than 17 y of age.

Elderly

CNS symptoms may occur more frequently.

Renal Function

Use with caution. Monitor patients for adverse reactions and adjust the dose as needed.

Hepatic Function

Use with caution.

Bacterial infections

Serious bacterial infections may begin with influenza-like symptoms or may coexist with or occur as complications during influenza; rimantadine has not been shown to prevent such complications.

Seizures

Increased incidence of seizures reported in patients with seizure history who received the related drug amantadine.

Transmission

Consider transmission of resistant virus when treating patients with contacts who are at a high risk of influenza A illness.

Overdosage

Symptoms

No information reported.

Patient Information

• Advise patients to use this medication for the full course of treatment.
• Inform patients that this medication only works on certain types of flu and that it does not treat other viral infections (eg, common cold).
• Advise patients to not take this medication until 2 wk after they receive a live intranasal flu vaccine, and to not receive a live nasal flu vaccine within 48 h after they stop taking this medication.
• Inform patients using the compounded oral suspension to shake well prior to administration.

Copyright © 2009 Wolters Kluwer Health.