Amifampridine
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From MedlinePlus, U.S. National Library of Medicine
Dosing in kidney impairment
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, Use in Specific Populations, and Clinical Pharmacology].
Dosing in liver impairment
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, Use in Specific Populations, and Clinical Pharmacology].
Preparation and administration
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.
Drug interactions
Check amifampridine against a medication listLabel text (3 paragraphs)
Drugs that lower seizure threshold: Concomitant use may lead to an increased risk of seizures. ( 7.1 ) Drugs with cholinergic effects (e.g., direct or indirect cholinesterase inhibitors): Concomitant use may increase the cholinergic effects of FIRDAPSE and of those drugs and increase the risk of adverse reactions. ( 7.2 )
7.1 Drugs that Lower Seizure Threshold The concomitant use of FIRDAPSE and drugs that lower seizure threshold may lead to an increased risk of seizures [see Warnings and Precautions ( 5.1 )]. The decision to administer FIRDAPSE concomitantly with drugs that lower the seizure threshold should be carefully considered in light of the severity of the associated risks.
7.2 Drugs with Cholinergic Effects The concomitant use of FIRDAPSE and drugs with cholinergic effects (e.g., direct or indirect cholinesterase inhibitors) may increase the cholinergic effects of FIRDAPSE and of those drugs and increase the risk of adverse reactions.
Contraindications
4 CONTRAINDICATIONS FIRDAPSE is contraindicated in patients with: A history of seizures [see Warnings and Precautions ( 5.1 )] Hypersensitivity to amifampridine phosphate or another aminopyridine [see Warnings and Precautions ( 5.2 )] FIRDAPSE is contraindicated in patients with: A history of seizures ( 4 ) Hypersensitivity to amifampridine or another aminopyridine ( 4 )
Safety data
Reported adverse events (FAERS)
Liver injury (LiverTox)
ELikelihood score E: Unlikely cause of clinically apparent liver injury, but experience with its use is limited.
Amifampridine is an orally available potassium channel blocker that increases acetylcholine in synaptic clefts of peripheral nerve endings and is used to treat the Lambert-Eaton myasthenic syndrome. Amifampridine is associated with a low rate of transient serum enzyme elevations during therapy but has not been linked with instances of clinically apparent acute liver injury.
ABCDEA: well known cause; E: unlikely cause. [HD]: high doses only.
Pregnancy and lactation
Pregnancy
8.1 Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to FIRDAPSE during pregnancy. Physicians are encouraged to enroll pregnant patients, or pregnant women may register themselves in the registry by calling 855- 212-5856 (toll-free), using the Fax number 877-867-1874 (toll-free), by contacting the Pregnancy Coordinating Center at firdapsepregnancyregistry@ubc.com, or by visiting the study website www.firdapsepregnancystudy.com. Risk Summary There are no data on the developmental risk associated with the use of FIRDAPSE in pregnant women.
In animal studies, administration of amifampridine phosphate to rats during pregnancy and lactation resulted in developmental toxicity (increase in stillbirths and pup deaths, reduced pup weight, and delayed sexual development) at doses associated with maternal plasma drug levels lower than therapeutic drug levels (see Animal Data ). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.
Data Animal Data Oral administration of amifampridine phosphate (0, 7.5, 22.5, or 75 mg/kg/day) to female rats prior to and during mating and continuing throughout organogenesis produced no adverse effects on embryofetal development. The highest dose tested is approximately 4 times the maximum recommended human dose (MRHD) of amifampridine (100 mg/day) on a body surface area (mg/m 2 ) basis. Oral administration of amifampridine phosphate (0, 9, 30, or 57 mg/kg/day) to pregnant rabbits throughout organogenesis produced no adverse effects on embryofetal development. The highest dose tested is approximately 6 times the MRHD of amifampridine on a body surface area (mg/m 2 ) basis.
Oral administration of amifampridine phosphate (0, 7.5, 22.5, or 75 mg/kg/day) to female rats throughout pregnancy and lactation resulted in an increase in stillbirths and pup deaths, reduced pup weight, and delayed sexual development in female pups at the mid and high doses tested. The no-effect dose (7.5 mg/kg/day amifampridine phosphate) for adverse developmental effects is associated with a plasma amifampridine exposure (AUC) less than that in humans at the MRHD of amifampridine.
Breastfeeding (LactMed)
No information is available on the clinical use of amifampridine during breastfeeding on the presence of amifampridine or the 3-N-acetyl-amifampridine metabolite in breastmilk. If amifampridine is required by the mother, it is not a reason to discontinue breastfeeding, but the infant should be carefully monitored for excessive crying or fussiness, adequate weight gain, and developmental milestones.
Supply and cost
Drug shortage status
Recalls (last 24 months)
Therapeutic equivalence (Orange Book)
Price ladder
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