Hydroxyethlamino Sulfonamide Derivatives

A compound of Formula I:

• or a pharmaceutically acceptable salt thereof, wherein:
• each Y is independently selected from hydrogen and deuterium;
• at least one of Y4, Y5a, Y5b, Y6a and Y6b is deuterium;
• R1 is hydrogen or —(CR3R4—O)n—R5;
• R2 is an isobutyl group having 0-9 deuterium;
• R3 and R4 are independently selected from H and C1-C4 alkyl;
• R5 is selected from an α-amino acid, —C(O)R6, —P(O)—(OM)2 and —S(O)—OM;
• R6 is hydrogen or an optionally substituted C1-C7 alkyl;
• each M is H, or a cation independently selected from Li+, Na+, K+, Mg2+, Ca2+, Ba2+, and NH4+;
• and
• n is 0 or 1.