Compstatin

Compstatin, a 13-residue cyclic peptide, is a potent inhibitor of the complement system C3 with species specificity. Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans). Compstatin inhibits only the activation of primates’ complement system. Compstatin exhibits IC₅₀ values of 63 μM and 12 μM for classical and alterative complement pathway, respectively^[1][2][3][4]. In Vitro: Compstatin exhibits an in vitro half-life in human blood of about2 hr^[2].
In solution, compstatin forms a β-turn at residues Gln-5–Gly-8 with the disulfide bridge Cys-2–Cys12, residues Ile-1–Val-4, and Thr-13, forming a hydrophobic cluster^[3].
In Vivo: Compstatin (21 mg/kg) produces complete inhibition when given as a combination of bolus injection and infusion. Compstatin completely inhibits in vivo heparin/protamine-induced complement activation without adverse effects on heart rate or systemic arterial, central venous, and pulmonary arterial pressures^[1].
Compstatin is stable in baboon plasma for more than 24 h^[1].
Pig xenografts survival is significantly longer in the Compstatin perfused group than in the control group^[2].