Amifampidine (Dosage)

Amifampridine is a drug that acts on the nervous system and is used for the symptomatic treatment of Lambert-Eaton myasthenic syndrome.

MECHANISM OF ACTION

Amifampridine blocks voltage-gated potassium channels by prolonging the depolarization of the presynaptic cell membrane, thus favoring the entry of calcium into the nerve ending. The consequent intracellular increase in calcium concentrations facilitates the exocytosis of vesicles containing acetylcholine, which in turn increases neuromuscular transmission. The result is an increase in muscle strength and in the amplitudes of the muscle action potential at rest.

CONTRAINDICATIONS

Hypersensitivity to amifampridine, epileptic patients; patients with uncontrolled asthma; patients with congenital cardiac QT interval syndromes.

Amifampridine is contraindicated in concomitance with sultopride, with drugs that can prolong QTc and with drugs with narrow therapeutic margin.

Do not use amifampridine during pregnancy. It should not be used during lactation since it is not known if amifampridine is excreted in human breast milk.

CAUTIONS

Cautions should be exercised when prescribing amifampridine in patients with hepatic or renal impairment. Caution in patients at risk of epileptic seizures: if a seizure occurs, stop amifampridine treatment immediately. Clinical and electrocardiographic monitoring should always be performed at the start of treatment and then once a year. Amifampridine is not recommended to treat children under 18 years old as there are no safety and efficacy data.

SIDE EFFECTS

Peripheral and perioral paresthesias; epigastric pain, diarrhea, nausea, abdominal pain; sleep disorders; convulsions, anxiety, dizziness, weakness, fatigue, headache, chorea, myoclonus; blurry vision; disturbances of the heart rhythm, palpitations; Raynaud's syndrome, cold extremities; cough, bronchial hypersecretion, asthma crisis in asthmatics patients or in those with a history of asthma; elevation of transaminases.

PHARMACOLOGIC INTERACTIONS

Amifampridine increases the risk of seizures with: antidepressants (tricyclics, selective inhibitors of serotonin reuptake), neuroleptics (phenothiazines and butyrophenones), mefloquine, bupropion, tramadol. Amifampridine increases the effect of direct or indirect inhibitors of cholinesterase, and decreases the effect of both inhibitors if amifampridine is taken in concomitance with: mivacurium, pipercurium, suxamethonium. Extreme precautions when administered concomitantly with drugs that are eliminated by metabolism or active secretion.

BRAND NAME

• Firdapse®