Dalfampridine Drug Information

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. 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.

Dosage Information

The maximum recommended dosage of dalfampridine extended-release tablet is one 10 mg tablet twice daily and should not be exceeded. Take doses approximately 12 hours apart. There is no evidence of additional benefit at doses greater than 10 mg twice daily.

Adverse reactions, including seizures, and discontinuations because of adverse reactions were more frequent at higher doses.

Administration Instructions Dalfampridine extended-release tablet can be taken with or without food.

Administer tablets whole; do not divide, crush, chew, or dissolve dalfampridine extended-release tablets. If a dose is missed, patients should not take double or extra doses.

Renal Monitoring

Prior to and During Treatment Estimated creatinine clearance (CrCl) should be known before initiating treatment with dalfampridine extended-release tablets, and monitored at least annually during treatment with dalfampridine extended-release tablets. CrCl can be estimated using the following equation (multiply by 0.85 for women): dalfampridine-equa

Dosage in Patients with Renal Impairment

In patients with mild renal impairment (CrCl 51 to 80 mL/min), dalfampridine extended-release tablet plasma levels may approach those seen at a dose of 15 mg twice daily, a dose that is 1.5 times the maximum recommended dose and may be associated with an increased risk of seizures. As mild renal impairment is common after age 50, estimating CrCl is particularly important in these patients. The potential benefits of dalfampridine extended-release tablet should be carefully considered against the risk of seizures in these patients.

Dalfampridine extended-release tablet is contraindicated in patients with moderate or severe renal impairment (CrCl≤50 mL/min).

• 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. Table 1: Adverse Reactions with an Incidence ≥2% of dalfampridine extended-release tablets-Treated Adult MS Patients and More Frequent with dalfampridine extended-release tablets Compared to Placebo in Controlled Clinical Trials Adverse Reaction Placebo (N=238) % Dalfampridine extended-release tablets 10 mg twice daily (N=400) % Urinary tract infection 8 12 Insomnia 4 9 Dizziness 4 7 Headache 4 7 Nausea 3 7 Asthenia 4 7 Back pain 2 5 Balance disorder 1 5 Multiple sclerosis relapse 3 4 Paresthesia 3 4 Nasopharyngitis 2 4 Constipation 2 3 Dyspepsia 1 2 Pharyngolaryngeal pain 1 2 Other Adverse Reactions Dalfampridine extended-release tablets has been evaluated in a total of 1,952 subjects, including 917 MS patients. A total of 741 patients have been treated with dalfampridine extended-release tablets for over six months, 501 for over one year and 352 for over two years. The experience in open-label clinical trials is consistent with the safety profile observed in the placebo-controlled clinical trials. As in controlled clinical trials, a dose-dependent increase in the incidence of seizures has been observed in open-label clinical trials with dalfampridine extended-release tablets in patients with MS as follows: dalfampridine extended-release tablets 10 mg twice daily 0.41 per 100 person-years (95% confidence interval 0.13 to 0.96); dalfampridine 15 mg twice daily 1.7 per 100 person-years (95% confidence interval 0.21 to 6.28). 6.2 Postmarketing Experience The following adverse reactions have been identified during post approval use with dalfampridine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure: vomiting, vertigo.

OCT2 Inhibitors Concurrent treatment with

OCT2 inhibitors, such as cimetidine, may cause increased exposure to dalfampridine . Elevated levels of dalfampridine increase the risk of seizures. The potential benefits of taking OCT2 inhibitors concurrently with dalfampridine extended-release tablets should be considered against the risk of seizures in these patients.

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. 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.

Pediatric Use Safety and effectiveness in patients younger than 18 years of age have not been established.

The use of dalfampridine extended-release tablets are contraindicated in the following conditions: History of seizure Moderate or severe renal impairment (CrCl≤50 mL/min) History of hypersensitivity to dalfampridine extended-release tablets or 4-aminopyridine; reactions have included anaphylaxis History of seizure Moderate or severe renal impairment (CrCl≤50 mL/min) History of hypersensitivity to dalfampridine extended-release tablets or 4-aminopyridine

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.