Lilly Flags Safety Risk in Compounded Zepbound Mixed With Vitamin B12

Eli Lilly & Co. warned that the active ingredient in its weight-loss blockbuster Zepbound could pose a risk to patients when mixed with vitamin B12, a combination sold by US drug compounders.

Lilly tested compounded products and found “significant levels of an impurity” resulting from a chemical reaction between the vitamin and the active ingredient, tirzepatide, it said Thursday.