Glatiramer Acetate

Chemical Identity

Property	Value
Molecular Weight	5,000-9,000 Da (average ~7,000 Da)
Composition	L-glutamic acid, L-lysine, L-alanine, L-tyrosine (random ratio)
CAS Number	147245-92-9
Route	SC injection

Structure

Glatiramer acetate (Copaxone) is a random copolymer of four amino acids: L-glutamic acid, L-lysine, L-alanine, and L-tyrosine in a fixed molar ratio (approximately 1.4:3.4:4.2:1.0). The random sequence creates a heterogeneous mixture of polypeptides that mimics the antigenic properties of myelin basic protein.

Mechanism of Action

Glatiramer acetate modulates the immune response in MS through multiple mechanisms: (1) competition with myelin antigens for MHC class II binding, (2) promotion of Th2 regulatory T-cell responses, (3) induction of neuroprotective factors, and (4) modulation of antigen-presenting cells. It shifts the immune balance from pro-inflammatory Th1 to anti-inflammatory Th2.

Clinical Applications

• Relapsing-remitting MS: Disease-modifying therapy (Copaxone)
• Clinically isolated syndrome: Delaying conversion to definite MS
• Generic versions: Glatopa (20 mg), authorized generics
• Pregnancy: Category B, considered relatively safe

Pharmacokinetics

• Half-life: Unknown (rapidly degraded at injection site)
• Bioavailability: Unknown (degraded by serum peptidases)
• Onset: Immune modulation within weeks
• Dosing: 20 mg SC daily or 40 mg SC 3x/week
• Route: SC injection

Safety and Side Effects

Injection site reactions (30-50%), immediate post-injection reaction (flushing, chest tightness, dyspnea - 10%), lipoatrophy, and rare anaphylaxis. No significant immunosuppression or laboratory monitoring required.

References

• Johnson, K.P., et al. (1995). Copolymer 1 for multiple sclerosis. Neurology, 45, 1268-1276.
• Comi, G., et al. (2001). European/Canadian glatiramer acetate trial. Lancet, 357, 1571-1577.