Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- Drug class
- Potassium Channel Blocker [EPC], Potassium Channel Antagonists [MoA]
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 897021
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Dalfampridine extended-release tablets are indicated as a treatment to improve walking in adult patients with multiple sclerosis (MS). This was demonstrated by an increase in walking speed [see Clinical Studies (14) ]. Dalfampridine is a potassium channel blocker indicated to improve walking in adult patients with multiple sclerosis (MS). This was demonstrated by an increase in walking speed ( 1 , 14 ).
About this medicine
Dalfampridine is a potassium channel blocker, available in a 10 mg tablet strength. Each tablet contains 10 mg dalfampridine, formulated as an extended-release tablet for twice-daily oral administration. Dalfampridine is also known by its chemical name, 4-aminopyridine, with the following structure: Dalfampridine extended-release tablets are available in a 10 mg strength and are white to off white, biconvex, oval shaped, beveled edge, film coated tablets, debossed “D 10” on one side and plain on other side, containing 10 mg of dalfampridine. Inactive ingredients consist of colloidal silicon dioxide, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, and titanium dioxide. Dalfampridine is a White to off white crystalline powder with a molecular weight of 94.1, CAS 504-24-5, and a molecular formula of C 5 H 6 N 2 . At ambient conditions, dalfampridine is soluble in water, methanol, acetone, isopropanol, acetonitrile and N,N-dimethylformamide. dalfampridine-struc
How it works
12.1 Mechanism of action The mechanism by which dalfampridine exerts its therapeutic effect has not been fully elucidated. Dalfampridine is a broad spectrum potassium channel blocker. In animal studies, dalfampridine has been shown to increase conduction of action potentials in demyelinated axons through inhibition of potassium channels.
Who should not take it
The use of dalfampridine extended-release tablets are contraindicated in the following conditions: History of seizure [see Warnings and Precautions (5.1)] Moderate or severe renal impairment (CrCl≤50 mL/min) [see Warnings and Precautions (5.2)] History of hypersensitivity to dalfampridine extended-release tablets or 4-aminopyridine; reactions have included anaphylaxis [see Warnings and Precautions (5.4)] History of seizure (4) Moderate or severe renal impairment (CrCl≤50 mL/min) (4) History of hypersensitivity to dalfampridine extended-release tablets or 4-aminopyridine (4)
Warnings and cautions
Dalfampridine extended-release tablets can cause seizures; the risk of seizures increases with increasing dalfampridine extended-release tablets doses; discontinue dalfampridine extended-release tablets and do not restart if a seizure occurs (5.1) Avoid concomitant use with other forms of 4-aminopyridine (4-AP, fampridine), since the active ingredient is the same ( 5.3 ) Dalfampridine extended-release tablets can cause anaphylaxis. Discontinue and do not restart dalfampridine extended-release tablets if this occurs (5.4) 5.1 Seizures Dalfampridine extended-release tablets can cause seizures. Increased incidence of seizures has been observed at 20 mg twice daily (2 times the maximum recommended dosage) in controlled clinical studies of 9 to 14 weeks duration with dalfampridine in patients with MS. In open-label extension trials in MS patients, the incidence of seizures during treatment with dalfampridine 15 mg twice daily (1.7/100PY) was over 4 times higher than the incidence during treatment with 10 mg twice daily (0.4/100PY). In the post-marketing period seizures have been reported. The majority of seizures occurred at the recommended dose and in patients without a history of seizures, and generally within days to weeks of starting therapy. Dalfampridine extended-release tablets has not been evaluated in patients with a history of seizures or with evidence of epileptiform activity on an EEG, as these patients were excluded from clinical trials. The risk of seizures in patients with epileptiform activity on an EEG is unknown, and could be substantially higher than that observed in dalfampridine extended-release tablets clinical studies. Permanently discontinue dalfampridine extended-release tablets in patients who have a seizure while on treatment. Dalfampridine extended-release tablets are contraindicated in patients with a history of seizures [see Contraindications (4)] . 5.2 Renal Impairment Dalfampridine extended-release tablets are eliminated through the kidneys primarily as unchanged drug [see Clinical Pharmacology (12.3)]. […]
Reported side effects
The following serious adverse reactions are described in more detail elsewhere in the labeling: •Seizures [see Warnings and Precautions ( 5.1 )] •Anaphylaxis [see Warnings and Precautions ( 5.4 )] The most common adverse events (incidence ≥2% and at a rate greater than the placebo rate) for dalfampridine extended-release tablets were urinary tract infection, insomnia, dizziness, headache, nausea, asthenia, back pain, balance disorder, multiple sclerosis relapse, paresthesia, nasopharyngitis, constipation, dyspepsia, and pharyngolaryngeal pain (6.1). To report SUSPECTED ADVERSE REACTIONS, contact Ascend Laboratories, LLC at 1-877-ASC-RX01 (877-272-7901) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. In three placebo-controlled clinical trials of up to 14 weeks duration, 4% (15/400) of patients treated with dalfampridine extended-release tablets 10 mg twice daily experienced one or more adverse reactions leading to discontinuation, compared to 2% (5/238) of placebo-treated patients. The adverse reactions leading to discontinuation of at least 2 patients treated with dalfampridine extended-release tablets and that led to discontinuation more frequently compared to placebo were headache (dalfampridine extended-release tablets 0.5%, placebo 0%), balance disorder (dalfampridine extended-release tablets 0.5%, placebo 0%), dizziness (dalfampridine extended-release tablets 0.5%, placebo 0%), and confusional state (dalfampridine extended-release tablets 0.3%, placebo 0%). Table 1 lists adverse reactions that occurred in ≥2% of patients treated with dalfampridine extended-release tablets 10 mg twice daily, and more frequently than in placebo-treated patients, in controlled clinical trials. […]
Interactions with other medicines
OCT2 Inhibitors: Concomitant use may cause an increased exposure and potential risk of seizures ( 7.1 ) 7.1 OCT2 Inhibitors Concurrent treatment with OCT2 inhibitors, such as cimetidine, may cause increased exposure to dalfampridine [see Clinical Pharmacology ( 12.3 )] . Elevated levels of dalfampridine increase the risk of seizures [see Warnings and Precautions ( 5.1 , 5.2 )]. The potential benefits of taking OCT2 inhibitors concurrently with dalfampridine extended-release tablets should be considered against the risk of seizures in these patients. 7.2 Baclofen No interaction was identified between dalfampridine and baclofen [see Clinical Pharmacology ( 12.3 )] .
Use in specific groups
Pregnancy: Based on animal data, may cause fetal harm (8.1) Geriatric use: Because elderly patients are more likely to have decreased renal function, it is particularly important to know the estimated CrCl in these patients before initiating dalfampridine extended-release tablets treatment ( 4 , 5.2 , 8.6 ) 8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with use of dalfampridine extended-release tablets in pregnant women. Administration of dalfampridine to animals during pregnancy and lactation resulted in decreased offspring viability and growth at clinically relevant doses [see Data]. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal Data Oral administration of dalfampridine to pregnant rats and rabbits throughout organogenesis resulted in no evidence of developmental toxicity in either species. The highest doses tested (10 mg/kg/day in rats, 5mg/kg/day in rabbits), which were associated with maternal toxicity, are approximately 5 times the MRHD on a body surface area (mg/m 2 ) basis. Oral administration of dalfampridine (0, 1, 3, and 9 to 6 mg/kg/day; high dose reduced during the second week of dosing) to female rats throughout pregnancy and lactation resulted in decreased offspring viability at the highest dose tested and decreased body weight in offspring at the mid and high doses. The no-effect dose for pre- and postnatal developmental toxicity in rats (1 mg/kg/day) is less than the MRHD on a mg/m 2 basis. 8.2 Lactation Risk Summary There are no data on the presence of dalfampridine in human milk, the effects of dalfampridine on the breastfed infant, or the effects on milk production. […]
If too much is taken
Three cases of overdose were reported in controlled clinical trials with dalfampridine extended-release tablets, involving two MS patients. The first patient took six times the currently recommended dose (60 mg) and was taken to the emergency room with altered mental state. The second patient took 40 mg doses on two separate occasions. In the first instance, she experienced a complex partial seizure and, in the second instance, a period of confusion. Both patients recovered by the following day without sequelae. Several cases of overdose are found in the scientific literature in which various formulations of dalfampridine were used, resulting in numerous adverse events including seizure, confusion, tremulousness, diaphoresis, and amnesia. In some instances, patients developed status epilepticus, requiring intensive supportive care and were responsive to standard therapy for seizures. In one published case report, an MS patient who ingested 300 mg of 4-aminopyridine (dalfampridine) developed a condition that resembled limbic encephalitis. This patient developed weakness, reduced awareness, memory loss, hypophonic speech, and temporal lobe hyperintensities on MRI. The patient’s speech and language and ambulation improved over time, and an MRI at 4 months after the overdose no longer showed signal abnormalities. At one year, the patient continued to have difficulty with short term memory and learning new tasks.
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This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 12 February 2024. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.