The present invention relates to an injectable pharmaceutical formulation comprising a compound of formula (I), said formulation being buffered to a pharmaceutically acceptable pH-value, especially a pH-value of from 2 to 6, in particular a pH value of from 3 to 5.5, preferred a pH-value of about 4 to 5, particularly preferred about 5. Compound (I) is lefamulin (BC-3781) which has antibiotic properties.
