Compounding pharmacies are suing the Food and Drug Administration so they can keep making imitation versions of popular—and lucrative—tirzepatide drugs, namely knockoffs of Mounjaro for diabetes and Zepbound for weight loss. Generally, compounding pharmacies make customized formulations of drugs for patients with specific needs, like when a patient has an allergy to a filler ingredient or if a child needs a liquid version of a drug that normally comes as a capsule.