Amifampridine is a voltage-gated potassium channel targeting regulator that specifically blocks Kv channels on neuronal membranes, inhibits potassium ion efflux, prolongs action potential repolarization, enhances presynaptic membrane calcium ion influx, and promotes acetylcholine vesicle release.

1、 Drug name

1. Common name: Amifampridine Tablets

2. Product Name: Firdapse ®

3. Other names: Amifampridine Phosphate

2、 Indications

Suitable for treating Lambert Eaton myasthenia gravis syndrome (LEMS) in adults and children aged 6 years and above.

3、 Specifications

Specification: 10mg per tablet.

4、 Main components

Active ingredient: Amifampridine

5、 Usage and dosage

1. Administration method: Oral. Can be taken with food or on an empty stomach.

2. Daily total dose: It should be taken in 3 to 5 doses within a day.

3. Recommended starting dose:

Adults (of any weight) and children weighing ≥ 45kg: 15mg to 30mg per day.

Children weighing less than 45kg: 5mg to 15mg per day.

4. Maximum dose limit:

Adults: The maximum single dose is 20mg, and the total daily dose does not exceed 100mg.

Children weighing less than 45kg: The maximum single dose is 10mg, and the total daily dose should not exceed 50mg.

6、 Dose adjustment

1. Omission treatment: If one dose is missed, please skip that dose and take the normal dose at the next scheduled medication time. Do not take double the dose at once.

2. Renal dysfunction:

Initial dose: Adopt the recommended minimum initial daily dose (15mg/day for adults/≥ 45kg for children; Children weighing less than 45kg: 5mg/day.

End stage renal disease (CLcr<15mL/min or dialysis): Dose recommendations cannot be provided.

Liver function injury: Patients with any degree of liver injury should use the lowest recommended initial daily dose.

NAT2 slow metabolism type: using the lowest recommended initial daily dose.

7、 Medication for special populations

1. Pregnancy: According to animal data, it may cause harm to the fetus.

2. Breastfeeding period: It is not yet clear whether it is secreted into human milk. It is necessary to weigh the benefits of breastfeeding against the potential risks of medication for infants.

3. Children: Safety and effectiveness have been determined for children aged 6 and above; Under 6 years old has not been determined yet.

4. Elderly: Clinical data shows no differences, it is recommended to start with low-end doses and consider liver, kidney, heart function decline and concomitant medication.

5. NAT2 slow metabolism type: significantly increased exposure (AUC increased by 5.6 to 9 times), requiring close monitoring starting from the lowest initial dose.

8、 Adverse reactions

1. Serious Warning:

Epilepsy: The incidence rate is about 2%, and it can occur even without a history of epilepsy. Individuals with a history of epilepsy are prohibited from using it.

Allergic reactions: Allergic symptoms, including rapid and severe allergic reactions, may occur.

2. Common adverse reactions (incidence>10%): sensory abnormalities (numbness/stabbing in the mouth and limbs), upper respiratory tract infections, abdominal pain, nausea, diarrhea, headache, elevated liver enzymes, back pain, hypertension, muscle spasms.

Children specific: Clinical significant weight loss may occur when the dose is ≥ 60mg/day.

9、 Contraindications

1. Patients with a history of epileptic seizures.

2. People who are allergic to amipyridine or other aminopyridine drugs.

10、 Drug interactions

1. Medications that lower the threshold of epilepsy: Co administration can increase the risk of epileptic seizures.

2. Drugs with cholinergic effects: Co administration can enhance cholinergic effects and increase the risk of adverse reactions.

3. Prohibition of combination use: other aminopyridine drugs (such as compound 3,4-diaminopyridine).

11、 Storage method

Tablets: Store at 20 ° C to 25 ° C (68 ° F to 77 ° F); allowable offset range is 15 ° C to 30 ° C (59 ° F to 86 ° F).

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