The present invention relates to pharmaceutically acceptable crystalline and amorphous salts of D-isoglutamyl-D-tryptophan as well as processes for their manufacture, pharmaceutical compositions comprising them, and their uses in the preparation of pharmaceutical compositions for the treatment of various conditions and/or diseases. In particular, the present invention relates to D-isoglutamyl-D-tryptophan potassium salt (1:1), D-isoglutamyl-D-tryptophan lithium salt (1:1), D-isoglutamyl-D-tryptophan calcium salt (2:1), D-isoglutamyl-D-tryptophan magnesium salt (2:1), and D-isoglutamyl-D-tryptophan organic ammonium salts(1:1).本發明係關於D－異麩胺醯基－D－色胺酸之藥學上可接受之結晶性與非晶質鹽，以及其製造方法，包含彼等之醫藥組合物，及其在製備醫藥組合物供治療各種症狀及/或疾病之用途。特定言之，本發明係關於D－異麩胺醯基－D－色胺酸鉀鹽(1：1)，D－異麩胺醯基－D－色胺酸鋰鹽(1：1)，D－異麩胺醯基－D－色胺酸鈣鹽(2：1)，D－異麩胺醯基－D－色胺酸鎂鹽(2：1)，及D－異麩胺醯基－D－色胺酸有機銨鹽(1：1)。
