The present invention relates to alkylglycoside-containing compositions and methods for increasing the stability, reducing the aggregation and immunogenicity, increasing the biological activity, and reducing or preventing fibrillar formation of a peptide, polypeptide, or variant thereof, for example parathyroid hormone (PTH) or PTH analogs, amylin, a monoclonal antibody, insulin, Peptide T or analog thereof, gastrin, gastrin releasing peptides, gastrin releasing peptide-like (GRP) proteins, epidermal growth factor or analog thereof.