Rimantadine Hydrochloride (Page 3 of 4)

GERIATRIC USE

Approximately 200 patients over the age of 64 were evaluated for safety in controlled clinical trials with rimantadine hydrochloride. Geriatric subjects who received either 200 mg or 400 mg of rimantadine daily for 1 to 50 days experienced considerably more central nervous system and gastrointestinal adverse events than comparable geriatric subjects receiving placebo. Central nervous system events including dizziness, headache, anxiety, asthenia, and fatigue, occurred up to two times more often in subjects treated with rimantadine than in those treated with placebo. Gastrointestinal symptoms, particularly nausea, vomiting, and abdominal pain occurred at least twice as frequently in subjects receiving rimantadine than in those receiving placebo. The gastrointestinal symptoms appeared to be dose related. In patients over 65, the recommended dose is 100 mg, daily (see CLINCAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).

OVERDOSAGE

As with any overdose, supportive therapy should be administered as indicated. Overdoses of a related drug, amantadine, have been reported with adverse reactions consisting of agitation, hallucinations, cardiac arrhythmia and death. The administration of intravenous physostigmine (a cholinergic agent) at doses of 1 to 2 mg in adults (Ref. 7) and 0.5 mg in children (Ref. 8) repeated as needed as long as the dose did not exceed 2 mg/hour has been reported anecdotally to be beneficial in patients with central nervous system effects from overdoses of amantadine.

DOSAGE AND ADMINISTRATION

FOR PROPHYLAXIS IN ADULTS AND CHILDREN

Adults (17 years and older)

The recommended adult dose of rimantadine hydrochloride is 100 mg twice a day. Study durations ranged from 11 days to 6 weeks in adult and elderly patients. In patients with severe hepatic dysfunction, severe renal impairment (CrCl 5 to 29 mL/min) or renal failure (CrCl ≤ 10 mL/min) and in elderly nursing home patients, a dose reduction to 100 mg daily is recommended. Because of the potential for accumulation of rimantadine metabolites during multiple dosing, patients with hepatic or renal impairment should be monitored for adverse effects.

Children (1 year to 16 years of age)

  • Study duration ranged from 5 weeks to 6 weeks in pediatric subjects.
  • In children 1 year to 9 years of age, rimantadine hydrochloride should be administered once a day, at a dose of 5 mg/kg but not exceeding 150 mg.
  • For children 10 years of age or older, use the adult dose.

(see Directions for Compounding of an Oral Suspension from Rimantadine Hydrochloride Tablets to prepare an oral suspension for administration to children and patients with difficulty swallowing tablets).

Children (Birth to 11 months)

The safety and efficacy of rimantadine hydrochloride for prophylaxis of influenza in pediatric patients younger than 1 year of age have not been established.

FOR TREATMENT IN ADULTS

Adults (17 years and older)

The recommended adult dose of rimantadine hydrochloride is 100 mg twice a day for 7 days. In patients with severe hepatic dysfunction, severe renal impairment (CrCl 5 to 29 mL/min) or renal failure (CrCl ≤ 10 mL/min) and elderly nursing home patients, a dose reduction to 100 mg daily is recommended. Because of the potential for accumulation of rimantadine metabolites during multiple dosing, patients with hepatic or renal impairment should be monitored for adverse effects. Rimantadine hydrochloride therapy should be initiated as soon as possible, preferably within 48 hours after onset of signs and symptoms of influenza A infection. Therapy should be continued for approximately seven days from the initial onset of symptoms.

Children (16 years of age and younger)

Rimantadine hydrochloride is not indicated for treatment of influenza in pediatric patients 16 years or younger.

Directions for the Compounding of an Oral Suspension from Rimantadine Hydrochloride Tablets (Final Concentration = 10 mg/mL)1

These directions are provided for use only during emergency situations, for patients who have difficulty swallowing tablets or where lower doses are needed. The pharmacist may compound a suspension (10 mg/mL) from rimantadine hydrochloride tablets, 100 mg using Ora-Sweet®.1 Other vehicles have not been studied.

To make an oral suspension (10 mg/mL) from 100 mg rimantadine hydrochloride tablets, you will need the following:

  • 100 mg tablets of rimantadine hydrochloride
  • Ora-Sweet® (a vehicle manufactured by Paddock Laboratories)
  • a graduated cylinder
  • a mortar and pestle
  • an Amber Glass or Polyethylene terephthalate plastic (PET) bottle
  • a funnel (optional)

1
Ora-Sweet® is a registered trademark of Paddock Laboratories

Compounding Procedures

A 100 mg tablet of rimantadine hydrochloride is required for each 10 mL of compounded oral suspension to make a concentration of 10 mg/mL.

A compounded oral suspension is stable for 14 days. Therefore, the maximum amount of oral suspension that can be dispensed to a patient should not exceed a 14 day supply.

Step A: Guidance for how to determine the Number of Tablets and Total Volume needed to compound a 10 mg/mL oral suspension for each patient

  1. Verify the prescribed dose is correct.
  2. Calculate the mg amount of rimantadine hydrochloride needed for the duration of therapy.
    (Daily Dose) × (Number of days) = (mg of rimantadine hydrochloride)
    For example, 75 mg/day × 10 days = 750 mg
  3. Round up the mg of rimantadine hydrochloride amount to the next 100 mg designation.
    For example, Round up 750 mg to 800 mg
  4. Calculate the Number of 100 mg tablets that are required for the compounded oral suspension.
    (Rounded mg of rimantadine hydrochloride) ÷ (100 mg/tablet) = (Number of tablets)
    For example, 800 mg ÷100 mg/tablet = 8 tablets
  5. Calculate the Total Volume of compounded oral suspension (10 mg/mL) (Rounded mg of rimantadine hydrochloride) ÷ (10 mg/mL) = (Total Volume)For example, 800 mg ÷ 10 mg/mL = 80 mL

Step B: Once the total Number of Tablets and Volume are determined then follow the procedures below for compounding the oral suspension (10 mg/mL) from rimantadine hydrochloride tablets 100 mg

Verify your calculations before you begin to compound an oral suspension.

A 100 mg tablet of rimantadine hydrochloride is required for each 10 mL’s of compounded oral suspension to make a concentration of 10 mg/mL.

  1. Place the required number of rimantadine hydrochloride 100 mg tablets into a clean mortar of sufficient size to contain the tablets and volume of vehicle, Ora-Sweet® used in Step 3.
  2. Grind the tablets and triturate to a fine powder using a pestle. Powder on the sides of the mortar or pestle should be removed using a spatula and incorporated into the trituration throughout the process.
  3. Slowly add approximately one-third (1/3) of the total volume of vehicle to the mortar while triturating until a uniform suspension is achieved.
  4. Transfer the suspension to an amber glass or a PET plastic bottle. Other types of bottles, such as non-PET plastic or uncolored bottles, have not been evaluated and should not be used. A funnel may be used to eliminate any spillage.
  5. Slowly add the second one-third (1/3) of the total volume of vehicle to the mortar, rinse the pestle and mortar by a triturating motion and transfer the contents into the bottle.
  6. Repeat the rinsing (Step 5) with the remaining one-third (1/3) of the vehicle, transferring the remaining contents to the fullest extent possible. Verify that the suspension is at the desired total volume or add additional vehicle if needed.
  7. Close the bottle using a child-resistant cap.
  8. Shake well to ensure homogeneous suspension. (Note: The active drug, rimantadine HCl readily dissolves in the specified vehicle. The suspension is caused by some of the inert ingredients of rimantadine hydrochloride tablets 100 mg which are insoluble in this vehicle.)

Labeling and Dispensing Information for the Compounded Oral Suspension

  1. Include an ancillary label on the bottle indicating “Shake Gently Before Use.” This compounded suspension should be gently shaken prior to administration to minimize the tendency for air entrapment with the Ora-Sweet® preparation. The need to shake the compounded oral suspension gently prior to administration should be reviewed with the parent or guardian when the suspension is dispensed.
  2. Provide an oral dosing device (a graduated oral syringe or spoon) that will measure the prescribed dose (in mL). If possible, mark or highlight the graduation corresponding to the appropriate dose on the oral syringe or spoon for each patient.
  3. Include an Expiration Date label according to storage condition (see below) and a “Discard any Unused Portion” label to the bottle. Instruct the parent or guardian that any remaining material following completion of therapy or after the expiration date on the label must be discarded.

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