Amifampridines are Safe and Effective for Managing LEMS Symptoms, Review Suggests

Amifampridines are Safe and Effective for Managing LEMS Symptoms, Review Suggests

Amifampridine-based medications are the most effective and safest options for managing symptoms of Lambert-Eaton myasthenic syndrome (LEMS), and should be chosen as the first-line management therapy for the rare autoimmune disorder, a review proposes.

The study, “Amifampridine for the treatment of Lambert-Eaton myasthenic syndrome,” was published in the Expert Review of Clinical Immunology.

The mainstay for symptomatic treatment of LEMS is 3,4-diaminopyridine (3,4-DAP). Due to issues with variability and reliability, 3,4-DAP was modified into a salt formulation called Firdapse (amifampridine phosphate).

Firdapse, developed by Catalyst Pharmaceuticals, is an oral prescription therapy for patients ages 17 and older for the symptomatic treatment of LEMS. It was approved by the U.S. Food and Drug Administration (FDA) less than a year ago in November 2018. The treatment restores the communication between muscle cells, improving patients’ muscle function.

In May, the FDA approved Ruzurgi (amifampridine) for the treatment of children ages 6–17 with LEMS, making it the only approved therapy for children with this condition.

Shin J. Oh, MD, an expert from the University of Alabama at Birmingham, reviewed all relevant literature on LEMS treatment, namely with aminopyridine and amifampridine.

The therapeutic role of amifampridines, including 3,4-DAP and Firdapse, has been extensively studied in neuromuscular diseases such as LEMS and myasthenia gravis.

In several randomized and non-randomized clinical trials, amifampridines have been shown to be well tolerated, safe, and the most effective medication for the management of LEMS symptoms. “Because of short-acting drug effects, it should be given three or four times a day,” Oh writes.

Amifampridine-based treatment has been associated with an increased risk of seizures, but doses below 80 mg a day shouldn’t be problematic, according to Oh. The most common side effects of 3,4-DAP and Firdapse are gastrointestinal discomfort and digital and perioral numbness or tingling sensation (paresthesia).

In LEMS, the communication between muscle cells can be so compromised that patients may sometimes experience a worsening of symptoms to the point of myasthenic crises, where an extreme episode of weakness leads to respiratory failure. This episode is known as a LEMS crisis. Amifampridines have been proven to be the medication of choice and to save lives in a LEMS crisis scenario.

Amifampridines can also be safely used for long periods of time and supplemented with Mestinon (pyridostigmine) to further ease LEMS symptoms without troublesome adverse events.

Available evidence indicates amifampridines are safe and the most effective therapy for the management of LEMS symptoms. As such, “AFPs [amifampridines] should be the drug of choice for the symptomatic treatment in LEMS,” Oh concludes.

With over three years of experience in the medical communications business, Catarina holds a BSc. in Biomedical Sciences and a MSc. in Neurosciences. Apart from writing, she has been involved in patient-oriented translational and clinical research.
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Margarida graduated with a BS in Health Sciences from the University of Lisbon and a MSc in Biotechnology from Instituto Superior Técnico (IST-UL). She worked as a molecular biologist research associate at a Cambridge UK-based biotech company that discovers and develops therapeutic, fully human monoclonal antibodies.
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With over three years of experience in the medical communications business, Catarina holds a BSc. in Biomedical Sciences and a MSc. in Neurosciences. Apart from writing, she has been involved in patient-oriented translational and clinical research.
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  • diagnosis, LEMS
  • amifampridine review study
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5 comments

  1. K White says:

    The variability of the 3.4 DAP is completely inaccurate. There were never any issues with the stability of the 3,4 DAP made by Jacobus Pharmaceutical.

    The very opposite of what has been written here is true. The phosphate salt version, Firdapse, has caused widespread and grave problems for numerous LEMS patients in the US. The main complaint is that it does not control their symptoms and there are now many US LEMS patients switching to Ruzurgi (their former 3,4 DAP) which is available to adults under off label guidelines.

  2. Vickie Moored says:

    I am a LEMS patient that has taken firdapse and 3,4 DAP. For many people the 3,4 DAP (now renamed Ruzurgi) is much more effective than firdapse. Personally for myself firdapse is about 1/3 of the efficacy of 3,4 DAP. There are a lot of side effects like firdapse takes 1-2 hours before it gets into your system but only lasts a few hours. DAP takes 20 minutes. On firdapse I have thigh pain and in general weaker. I feel like I have weights on my legs. I also get blurred vision on firdapse especially at night. It is hard walking up steps while on firdapse. When I get to the top I have to sit down to rest. I am also unbalanced when walking. When I was on DAP for 4 years I had none of the problems described above. I would go back to Ruzurgi in a minute. These medicines for me are like night and day.

  3. Jacque says:

    As a LEMS patient I can attest to the fact that this article is an absolute lie regarding the third paragraph.’3,4 Dap was very effective with no side effects. Firdapse is 90 percent ineffective with terrible side affects. I know. I am forced to take Firdapse currently. The phosphate salts may be to blame. Who knows. I am appalled at your apparent lack of true knowledge regarding this topic. I can only imagine who hired you to write this propaganda to help promote their expensive ineffective “alternative “ to DAP.

  4. LM says:

    Just reading paragraph four proves that the author has no knowledge of Lems. “The treatment restores the communication between muscle cells.” This is NOT the problem in patients with Lems.
    3,4 Dap (diaminopyrine) has no effect whatever on communication between muscle cells. It allows additional release of acetylcholine that has been compromised at the neuromuscular junction, allowing communication between nerves and muscles.

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