GLP1R and obesity due to melanocortin 4 receptor deficiency: Based on these two important targets, Lilly developed tirzepatide (Zepbound®), the first marketed dual-target agonist (GIP/GLP-1) obesity treatment injection, which provides better weight control than semaglutide and dulaglutide (Fig. 8b).266 The drug has previously been approved as an adjunctive therapy to diet and exercise to improve glycemic control in T2DM.267,268 Tirzepatide consists of 39 amino acids, 37 of which are naturally occurring (or coded) and two are non-naturally occurring.