According to the Ph. Eur. monograph, tacrolimus is defined as a mixture of several macrolide lactones, with the main component being (3S,4R,5S,8E,9S,10R,11S,12S,15S)-5,9,11,15-tetrahydroxy-3,7,12,16-tetramethyl-2-(1E,3E,5E,7E,9E,11E,13E,15E)-1,17-dihydroxy-4,6,8,10,14-pentaoxoheptadeca-1,3,5,7,9,11,13,15-octaen-2-ylmethyl-2-(2R)-2,6-dideoxy-3-O-methyl-α-D-ribo-hexopyranosyloxy]-3-(1R)-1-hydroxyethyl]oxolane-2-one.

European Pharmacopoeia Monograph: Tacrolimus**

The European Pharmacopoeia monograph for tacrolimus provides a comprehensive set of standards for the quality control and assurance of this critical medication. The monograph ensures that tacrolimus products available in Europe meet the required standards of quality, purity, and potency. By following the guidelines set out in the monograph, manufacturers can ensure that their products are safe and effective for use in patients.