BioMarin Seeking US Approval of LEMS Drug

A drug approved in Europe to treat Lambert-Eaton myasthenic syndrome is now being tested in the United States; clinical trial participants sought

Article Highlights:
  • BioMarin Pharmaceutical is conducting a trial of 3,4-diaminopyridine phosphate (3,4-DAP) in adults with Lambert-Eaton myasthenic syndrome (LEMS) at eight U.S. centers.
  • 3,4-DAP increases the release of the muscle-activating chemical acetylcholine.
  • The drug is approved in Europe for the treatment of LEMS. The company plans to seek approval for its version from the U.S. Food and Drug Administration.
  • Individuals with a confirmed LEMS diagnosis who are at least 18 years of age and meet other study criteria are being sought.
  • 3, 4-DAP is also available through expanded access programs, which are not part of the BioMarin trial.
by Margaret Wahl on November 18, 2011 - 6:00am

BioMarin Pharmaceutical of Novato, Calif., is conducting a multicenter study of 3,4-diaminopyridine phosphate (3,4-DAP), also known as amifampridine phosphate, in adults with Lambert-Eaton myasthenic syndrome (LEMS).

There are eight U.S. trial sites, with additional sites planned for France, Germany, Italy, Poland and Spain.

In December 2009, BioMarin received approval to market 3,4-DAP as Firdapse for LEMS in the European Union.

The company is planning to seek approval from the U.S. Food and Drug Administration (FDA) to market the drug for LEMS in the United States.

3,4-DAP increases acetylcholine release

3,4-DAP increases the release of acetylcholine, a chemical transmitter of signals from the nervous system that activates muscle fibers.

LEMS is caused by a misdirected attack of the immune system on nerve endings at the neuromuscular junction, the place where nerve and muscle fibers connect. The disorder causes muscle weakness and sometimes other symptoms, such as dry mouth or constipation.

In the United States, the disease is treated with medications that suppress the immune system and/or medications that slow the breakdown of acetylcholine (cholinesterase inhibitors).

Trial participants must meet study criteria

Prospective participants in the clinical trial must:

  • be at least 18 years old;
  • have a confirmed diagnosis of LEMS;
  • have normal respiratory and swallowing function;
  • if taking cholinesterase inhibitors, have been on a stable dose for at least seven days prior to study screening;
  • if taking immunosuppressant drugs, have been on a stable dose for at least 90 days prior to study screening;
  • have a normal electrocardiogram (EKG); and
  • meet other study criteria.

To participate in the BioMarin 3,4-DAP study

U.S. sites are in Birmingham, Ala.; Scottsdale, Ariz.; Little Rock, Ark.; Orange, Calif.; Jacksonville, Fla.; Kansas City, Kan.; New York City; and Philadelphia.

Contact Kenny Jones at BioMarin in California at or (415) 506-6700.

For details, see A Phase 3 study of Amifampridine Phosphate in Patients With Lambert-Eaton Myasthenic Syndrome (LEMS); or enter NCT01377922 into the search box at

Access to 3,4-DAP other than through the BioMarin study

Access to 3,4-DAP for treatment of LEMS and other conditions via an expanded access program exists at several sites. An expanded access program is a means by which manufacturers make investigational new drugs available under certain circumstances outside a formal clinical trial.

The drug is being supplied by Jacobus Pharmaceutical, based in Princeton, N.J., and possibly other companies, at medical centers in several U.S. cities.

For up-to-date information, go to, and enter 3,4-diaminopyridine in the search box.

Editor's note: This story was updated 1/6/12 to reflect the availability of 3,4-diaminopyridine through expanded access programs.


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