3,4-Diaminopyridine

freely soluble in water, and slightly soluble in solvents ethanol, methanol and acetic acid

12.2 [ug/mL] (The mean of the results at pH 7.4)

Breastfeeding; Lactation; Neuromuscular Agents; Potassium Channel Blockers;

FDA approved drugs -> Active ingredient

EMA approved medicines: Human medicine

Danger

H300 (94.2%): Fatal if swallowed [Danger Acute toxicity, oral]

P260, P261, P262, P264, P264+P265, P270, P271, P280, P284, P301+P316, P302+P352, P304+P340, P305+P351+P338, P316, P319, P320, P321, P330, P332+P317, P337+P317, P361+P364, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 52 reports by companies from 10 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Amifampridine has had limited clinical use, but adverse events have been largely neurologic and gastrointestinal. Serum ALT elevations were not reported in the prelicensure studies of amifampridine but were reported as occurring in a small proportion of patients in safety reviews by the Food and Drug Administration. Nevertheless, there have been no reports of clinically apparent liver injury associated with its use. Thus, liver injury from amifampridine must be rare if it occurs at all.

Drug Induced Liver Injury Rank (DILIrank 2.0)

Amifampridine

vNo-DILI-concern

0

No match

DOI:10.1016/j.drudis.2016.02.015

N - Nervous system

QN - Nervous system

Administration of amifampridine to patients with LES in clinical trials resulted in improvement of the compound muscle action potential (CMAP), muscle function, and quantitative myasthenia gravis (QMG) score. One case of a slight prolongation of the QTc interval in male patient with LEMS and euthyroid Hashimoto’s disease treated with 90 mg of amifampridine in combination with 100 mg azathioprine was reported. _In vitro_, amifampridine was shown to modulate cardiac conduction and induce phasic contractions in different arteries from several species. In addition, it stimulated potassium-evoked dopamine and noradrenaline release in rat hippocampal slices and upregulate acetylcholine release in the brain. It may also potentiate adrenergic and cholinergic neuromuscular transmission in the gatrointestinal tract. In a single pharmacokinetic study, no effect was observed of amifampridine phosphate on cardiac repolarization as assessed using the QTc interval. There were no changes in heart rate, atrioventricular conduction or cardiac depolarization as measured by the heart rate, PR and QRS interval durations.

Amifampridine is a symptomatic treatment that increases acetylcholine concentrations at the neuromuscular junction. It selectively blocks presynaptic fast voltage-gated potassium channels, thereby prolonging cell membrane depolarization and action potential, and augmenting calcium transport into the nerve endings. Increased intracellular calcium enhances the exocytosis of acetylcholine-containing vesicles and enhances impulse transmission at central, autonomic, and neuromuscular synapses. Amifampridine improves muscle strength and resting compound muscle action potential (CMAP) amplitudes with an overall weighted mean difference of 1.69 mV.

RU4S6E2G0J

AMIFAMPRIDINE

Established Pharmacologic Class [EPC] - Potassium Channel Blocker

Mechanisms of Action [MoA] - Potassium Channel Antagonists

Amifampridine is a Potassium Channel Blocker. The mechanism of action of amifampridine is as a Potassium Channel Antagonist.

Drugs used for their actions on skeletal muscle. Included are agents that act directly on skeletal muscle, those that alter neuromuscular transmission (NEUROMUSCULAR BLOCKING AGENTS), and drugs that act centrally as skeletal muscle relaxants (MUSCLE RELAXANTS, CENTRAL). Drugs used in the treatment of movement disorders are ANTI-DYSKINESIA AGENTS.

A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.

Orally-administered amifampridine is rapidly absorbed in humans to reach the peak plasma concentrations within by 0.6 to 1.3 hours. A single oral dose of 20 mg amifampridine in fasted individuals resulted in mean peak plasma concentrations (Cmax) ranging from 16 to 137 ng/mL. Bioavailability is approximately 93-100% based on recoveries of unmetabolised amifampridine and a major 3-N-acetylated amifampridine metabolite in urine. Food consumption decreases amifampridine absorption and exposure with a decrease in the time to reach maximum concentrations (Tmax). It is approximated that food consumption lowers the Cmax on average by ~44% and lowers AUC by ~20%. based on geometric mean ratios. Systemic exposure to amifampridine is affected by the overall metabolic acetylation activity of NAT enzymes and NAT2 genotype. The NAT enzymes are highly polymorphic that results in variable slow acetylator (SA) and rapid acetylator (RA) phenotypes. Slow acetylators are more prone to increased systemic exposure to amifampridine, and may require higher doses for therapeutic efficacy.

Following oral administration, more than 93% of total amifampridine is renally eliminated within 24 hours. About 19% of the total renally-excreted dose is in the parent drug form, and about 74-81.7% of the dose is in its metabolite form.

In healthy volunteers, the volume of distribution for plasma amifampridine indicated that RUZURGI is a drug with a moderate to a high volume of distribution. After a 2 mg/kg infusion in rats, the volume of distribution at steady-state was 2.8 ± 0.7 L/kg. Drug concentrations were highest in organs of excretion, including the liver, kidney, and the gastrointestinal tract, and some tissues of glandular function, such as lacrimal, salivary, mucous, pituitary, and thyroid glands. Concentrations in tissues are generally similar to or greater than concentrations in plasma.

Overall clearance of amifampridine is both metabolic and renal; it is primarily cleared from the plasma via metabolism by N-acetylation. Following oral administration of a single 20 or 30 mg dose of RUZURGI to healthy volunteers, amifampridine apparent oral clearance (CL/F) was 149 to 214 L/h.