Compounds comprising peptides capable of binding C3 protein and inhibiting complement activation are disclosed. The compounds comprise compstatin analogs in which the N-terminus contains an added or substituted component that improves (1) the peptide's binding affinity to C3 or its fragments, (2) the peptide's solubility in aqueous liquids, (3) the peptide's plasma stability, (4) the peptide's in vivo retention and/or (5) the peptide's bioavailability, as compared with an unmodified compstatin peptide under equivalent conditions. Pharmaceutical compositions and methods of using the compounds are also disclosed.
