Glatiramer acetate

Glatiramer Acetate or glatiramer (GA; trademark Copaxone® by Teva Pharmaceutical Industries, Ltd.) is licensed in much of the world for relapsing-remitting multiple sclerosis (MS). In early trials of the drug, it was known as Copolymer-1 and Cop-1.

Glatiramer reduces the average relapse rate in people with the relapsing-remitting (RRMS) form MS. The formation of new MS-related lesions in the central nervous system and rate of brain atrophy are also reduced.

Licensing

Glatiramer was licensed for the treatment of RRMS in the USA by the Food and Drug Administration (FDA) in December 1996. It has been approved in Britain, Canada, Australia and most of Europe by the national drug regulation organisations.

Structure

Glatiramer is a random chain polymer of amino acids - glutamic acid, lysine, alanine and tyrosine (hence GLATiramer). It is synthesized in solution from a molar ratio of alanine to lysine to glutamic acid to tyrosine of approximately 5 : 3 : 1.5 : 1 : 1. The amino acids in the reaction mixture and presented in the carboxyamino acid anhydride form.

Mechanism of action

Originally glatiramer was designed to mimic myelin basic protein, a component of myelin, with the intention of inducing EAE (an animal disease used as a scientific model for MS). Unexpectedly, it was found to suppress the disease and as a result came to be trialed in human MS. For this reason, it was originally believed to act as a decoy by drawing the immune system's attack away from myelin.

Currently, the precise mechanism of action of glatiramer is considered unknown. The is some evidence that it converts the body's immune response from a Th1 type to a Th2 one, promotes suppressor T cells or acts as an altered peptide ligand.

Administration

The drug is self-administered by daily sub-cutaneous injections of 20 mg.

Adverse effects

It is generally well tolerated. The most common problem that users experience are injection site reactions which include itching and inflammation. These reactions can be mitigated against by revolving the injection site, preparing it with ice and ensuring that the drug is at room temperature before injecting. Some users experience flushing, chest and joint pains, weakness, nausea, anxiety and muscle stiffness. These tend to resolve after about a quarter of an hour without special treatment.

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