Amifampridine Phosphate

Class: Other Miscellaneous Therapeutic Agents
Chemical Name: phosphoric acid;pyridine-3,4-diamine
Molecular Formula: C₅H₁₀N₃O₄P
CAS Number: 446254-47-3
Brands: Firdapse

Medically reviewed by Drugs.com on Jun 28, 2021. Written by ASHP.

Introduction

Amifampridine phosphate is a broad spectrum potassium channel blocker.

Uses for Amifampridine Phosphate

Amifampridine phosphate has the following uses:

Amifampridine phosphate is a potassium channel blocker indicated for the treatment of Lambert-Eaton myasthenic syndrome (LEMS) in adults.

Amifampridine Phosphate Dosage and Administration

General

Amifampridine phosphate is available in the following dosage form(s) and strength(s):

• Tablets: 10 mg, functionally scored.

Clinicians should be aware that there are 2 different formulations of amifampridine: amifampridine phosphate (Firdapse) and amiframpidine (Ruzurgi). Both are available as scored tablets containing 10 mg of amifampridine and are labeled for use in the treatment of Lambert-Eaton myasthenic syndrome (LEMS). Amifampridine phosphate (Firdapse) is labeled for use in adults, and amiframpidine (Ruzurgi) is labeled for use in pediatric patients 6 to less than 17 years of age.

Dosage

It isessentialthat the manufacturer's labeling be consulted for more detailed information on dosage and administration of this drug. Dosage summary:

Adults

Dosage and Administration

• The usual recommended starting dosage is 15 mg to 30 mg daily taken orally in divided doses (3 to 4 times daily).

• The recommended starting dosage is 15 mg daily taken orally in 3 divided doses for patients with renal impairment (CLcr 15–90 mL/min), hepatic impairment, and in known N-acetyltransferase 2 (NAT2) poor metabolizers.

• Dosage can be increased by 5 mg daily every 3 to 4 days.

• Dosage is not to exceed a maximum of 80 mg daily.

• The maximum single dose is 20 mg.

Cautions for Amifampridine Phosphate

Contraindications

Amifampridine phosphate is contraindicated in patients with:

• A history of seizures.

• Hypersensitivity to amifampridine or another aminopyridine.

Warnings/Precautions

Seizures

Amifampridine phosphate can cause seizures. Seizures have been observed in patients without a history of seizures taking amifampridine phosphate at the recommended do...