Glycopegylated erythropoietin formulations

A pharmaceutical composition comprising about 0.1 mg/ml to about 1 mg/ml of an erythropoietin peptide and a buffer, the composition having a pH from 5.5 to 6.5, wherein the erythropoietin peptide comprises a glycosyl linking group attached to an amino acid residue or a glycosyl residue of said peptide, wherein the amino acid residue is selected from the group consisting of serine, threonine, and asparagine, said glycosyl linking group comprising a modified sialyl residue having the formula:

• wherein
• R2 is H, CH2OR7, COOR7, COO− or OR7
• wherein
• R7 represents H, substituted or unsubstituted alkyl or substituted or unsubstituted heteroalkyl;
• R3 and R4 are members independently selected from H, substituted or unsubstituted alkyl, OR8, NHC(O)R9
• wherein
• R8 and R9 are independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl or sialic acid;
• s is an integer from 1 to 20;
• f is an integer from 1 to 2500;
• and
• Q is a member selected from H and substituted or unsubstituted C1-C6 alkyl;
• and
• wherein the buffer comprises one or more members selected from the group consisting of acetate, carbonate, citrate, glycinate, histidine, lactate, maleate, phosphate, succinate, tartrate, and tris;
• and
• the pharmaceutical composition shows no detectable level of aggregation of the erythropoietin peptide as measured by SEC-HPLC after three months at a temperature of 5° C. or lower.