Dosing and uses of Ampyra (dalfampridine)
Adult dosage forms and strengths
tablet, extended-release
- 10mg
Multiple Sclerosis
Indicated to improve walking in patients with multiple sclerosis by increasing walking speed
10 mg PO bid with or without food; take doses 12 hr apart
Extended-release tablet; swallow tablet whole and do not chew, crush, divide, or dissolve tablets
Renal & Hepatic Impairment
Renal impairment
- Moderate-to-severe (CrCl ≤50 mL/min): Contraindicated due to increased risk of seizures
- Mild (CrCl 51-80 mL/min): Risk of seizure unknown, but plasma levels may be similar to levels of 15 mg PO bid, a dose that is possibly associated with increased seizure risk
Hepatic impairment
- Not studied, but not expected to change dosing recommendations (primarily renal excretion)
Pediatric dosage forms and strengths
<18 years: Safety and efficacy not established
Geriatric dosage forms and strengths
Multiple Sclerosis
It is important to know the estimated CrCl in the elderly prior to initiating therapy because the elderly are more likely to have decreased renal function
10 mg PO bid with or without food in normal renal function; take doses 12 hr apart
Extended-release tablet; swallow tablet whole and do not chew, crush, divide, or dissolve tablets
Renal & Hepatic Impairment
Mild renal impairment (CrCl 51-80 mL/min), Risk of seizure unknown, but plasma levels may be similar to levels of 15 mg PO bid, a dose that is possibly associated with increased seizure risk
Moderate or severe renal impairment (CrCl ≤50 mL/min): Contraindicated due to increased risk of seizures
Hepatic impairment: Not studied but not expected to change dosing recommendations (primarily renal excretion)
Ampyra (dalfampridine) adverse (side) effects
>10%
Urinary tract infection (12%)
1-10%
Insomnia
Dizziness
Headache
Nausea
Asthenia
Back pain
Balance disorder
Multiple sclerosis relapse
Paresthesia
Nasopharyngitis
Constipation
Dyspepsia
Pharyngolaryngeal pain
Dose-related increased risk of seizures
Postmarketing Reports
Seizures; 4.6 per 1000 patient-years of use, which is comparable to the rate of seizures seen in the overall MS population
Vomiting
Warnings
Contraindications
Hypersensitivity
Moderate or severe renal impairment (CrCl ≤50 mL/min)
History of seizure
Cautions
Discontinue if seizure occurs and do not restart; majority of seizures happened within days to weeks after starting the recommended dose and occurred in patients having no history of seizures
Age-related decreases in renal function, and mild renal impairment is common after age 50 yr, even when serum creatinine is normal; renal function should be assessed by estimating creatinine clearance
Do not take with other forms of 4-aminopyridine (4-AP, fampridine) to avoid adverse reaction due to the same active ingredient
Estimate CrCl before initiating (see Contraindications and Renal Impairment)
Do not double dose or take extra if dose missed
Anaphylaxis and severe allergic reactions; signs and symptoms have included respiratory compromise, urticaria, and angioedema of the throat and or tongue; discontinue immediately and do not restart (see Contraindications)
UTIs reported more frequently in clinical trials vs. placebo
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown if excreted in breast milk; discontinue drug or breast feeding
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Ampyra (dalfampridine)
Mechanism of action
Mechanism not completely understood, but in animal studies shown to block potassium channels, to delay repolarization and to increase duration of action potentials in demyelinated axons
Does not prolong QTc intervaL
Pharmacokinetics
Half-life elimination: 5-7 hr (prolonged up to 3 times longer in severe renal impairment)
Absorption: rapid and completely absorbed from GI tract; 96% relative bioavailability to aqueous oral solution; extended-release tablet
Vd: 2.6 L/kg
Peak Plasma Time: 3-4 hr
Peak Plasma Concentration: 17.3 ng/mL-21.6 ng/mL (slight increase with food, 12-17%)
Protein Bound: 1-3%
Metabolism: Minimal, 90.3% eliminated unchanged; 2 inactive metabolites (3-hydroxy-4-aminopyridine and 3-hydroxy-4-aminopyridine sulfate)
Excretion: feces (0.5%), urine (95.9%)
