Glucagon receptor signaling — my results so far

This one has a reasonably settled answer, so here it is. The pharmacokinetics explain nearly every practical question asked here. Albumin binding above 99% slows clearance enough to make weekly dosing possible; a terminal half-life near a week means four to five weeks to steady state and therefore a four-week titration interval; subcutaneous bioavailability around 89% means injection site barely matters. Those three facts answer most timing questions before they are asked.

FDA_TrackerJim said:

The pharmacokinetics explain nearly every practical question asked here.

Agreed, and the adaptation point cuts both ways: tachyphylaxis to gastric emptying is why tolerability improves, and it is also why people who were relying on physical fullness feel the effect fade while the appetite effect is still working.

Happy to go further on any of that.

Dr.EndoIndy said:

Following the glucagon co-agonists mostly for the liver endpoints rather than the weight ones, which seems to be the opposite of how they get…

Same pattern here, and in the same order.

Adding the clinical framing, because it changes how the question reads.

Glucagon receptor pharmacology in triple agonists (retatrutide), relevant to the glucagon co-agonists: the glucagon component is the most controversial because glucagon traditionally raises blood glucose. So why include it in an anti-obesity drug?

Key insight: glucagon increases energy expenditure (thermogenesis), promotes hepatic lipid oxidation, and reduces appetite through distinct CNS mechanisms. The hyperglycemic effect is counterbalanced by the GLP-1 component's insulin secretagogue action.

Net result: more weight loss through increased expenditure (glucagon) + decreased intake (GLP-1/GIP), with neutral or improved glycemia. An elegant pharmacological balancing act[1].