Firdapse Dosage

Generic name: amifampridine phosphate 10mg
Dosage form: tablet
Drug class: Cholinergic muscle stimulants

Medically reviewed by Drugs.com. Last updated on Sep 8, 2023.

Dosage Information

The recommended dosage regimen of FIRDAPSE for adults and pediatric patients 6 years of age and older is included in Table 1. For pediatric patients, the recommended dosing regimen is dependent on body weight. Dosage should be increased every 3 to 4 days based on clinical response and tolerability. Titration increments should not exceed those shown in Table 1.

Table 1: Recommended Oral Dosage for the Treatment of LEMS in Adults and Pediatric Patients 6 Years of Age and Older
*See Dosage and Administration (2.5) for a method to achieve these doses
Age and Body Weight	Initial Daily Dosage*	Titration Regimen	Maximum Single Dose	Maximum Total Daily Maintenance Dosage
Adults (any weight) Pediatric patients weighing 45 kg or more	15 mg to 30 mg daily, in 3 to 4 divided doses	Increase total daily dosage by 5 mg every 3 or 4 days	20 mg	80 mg Given in divided doses
Pediatric patients weighing less than 45 kg	5 mg to 15 mg daily, in 3 to 4 divided doses	Increase total daily dosage by 2.5 mg every 3 or 4 days	10 mg	40 mg Given in divided doses

Missed Dose

If a dose is missed, patients should not take double or extra doses.

Patients with Renal Impairment

The recommended starting dosage of FIRDAPSE in patients with renal impairment [creatinine clearance (CLcr) 15 to 90 mL/min] is the lowest recommended initial daily dosage (i.e., 15 mg daily for pediatric patients weighing 45 kg or more and for adults, and 5 mg daily for pediatric patients weighing less than 45 kg) taken orally in divided doses. No dosage recommendation for FIRDAPSE can be made for patients with end-stage renal disease [see Dosage and Administration (2.1), Use in Specific Populations (8.6), and Clinical Pharmacology (12.3)].

Patients with Hepatic Impairment

The recommended starting dosage of FIRDAPSE in patients with any degree of hepatic impairment is the lowest recommended initial daily dosage (i.e., 15 mg daily for pediatric patients weighing 45 kg or more and for adults, and 5 mg daily for pediatric patients weighting less than 45 kg) taken orally in divided doses [see Dosage and Administration (2.1), Use in Specific Populations (8.7), and Clinical Pharmacology (12.3)].

Known N-acetyltransferase 2 (NAT2) Poor Metabolizers

The recommended starting dosage of FIRDAPSE in known N-acetyltransferase 2 (NAT2) poor metabolizers is the lowest recommended initial daily dosage (i.e., 15 mg daily for pediatric patients weighing 45 kg or more and for adults, and 5 mg daily for pediatric patients weighing less than 45 kg) taken orally in divided doses [see Dosage and Administration (2.1), Use in Specific Populations (8.8), and Clinical Pharmacology (12.5)].

Administration Instructions

FIRDAPSE can be taken without regard to food.

Preparation of a 1mg/mL Suspension (see the Instructions for Use for full instructions on how to prepare the 1mg/mL suspension)

When patients require a dosage in less than 5 mg increments, have difficulty swallowing tablets, or require feeding tubes, a 1 mg/mL suspension can be prepared (e.g., by placing the required number of tablets in a 50 to 100 mL container, adding 10 mL of sterile water for each tablet, waiting for 5 minutes, and shaking well for 30 seconds).

Crushing the tablets prior to making the suspension is not necessary. After preparation of the suspension, an oral syringe can be used to draw up and administer the correct dose by mouth or by feeding tube.

Storage of 1mg/mL Prepared Suspension
Refrigerate the suspension between doses and shake well before drawing up each dose. The suspension can be stored under refrigeration
[between 2°C and 8°C (36°F and 46°F)] for up to 24 hours. Discard any unused portion of the suspension after 24 hours.