I went looking for why the dosing schedule is what it is and found that almost every practical question on this board has a pharmacokinetic answer nobody states.
What would genuinely help is knowing which effects tachyphylax and which persist, because the answer explains why tolerability improves while the appetite effect keeps working.
Practical detail welcome, however dull — the duller the better.
tommy_boulder said:I went looking for why the dosing schedule is what it is and found that almost every practical question on this board has a pharmacokinetic answer…
Pharmacist here. I want to add the drug interaction perspective on the pharmacology.
Key points from a pharmacokinetic standpoint:
- GLP-1 agonists delay gastric emptying, which can affect Tmax of co-administered oral medications
- Monitor patients on warfarin (INR), levothyroxine (TSH), and oral contraceptives during dose titration
- The albumin-binding mechanism of semaglutide (C-18 fatty acid linker) gives it the ~168-hour half-life that enables weekly dosing
- Steady state is reached at approximately 4-5 weeks after dose initiation or adjustment
Re: the pharmacology specifically — the pharmacology here is well-characterized and the clinical implications are straightforward.
kate.chem said:I want to add the drug interaction perspective on the pharmacology.
kate.chem has the substance of this right. The condition it depends on is worth stating. The mechanism is more central than most summaries suggest. Receptor agonism in the arcuate nucleus activates POMC neurons and inhibits AgRP/NPY signalling, and the downstream MC4R pathway is the same one disrupted in monogenic obesity — convergent genetic evidence that the target is the right one. Peripherally there is glucose-dependent insulin secretion, glucagon suppression and delayed gastric emptying, but the gastric component largely adapts over months while the central effect persists, which is why the durable effect is appetite rather than fullness.
Happy to go further on any of that.
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Browse GL Biochemtommy_boulder said:I went looking for why the dosing schedule is what it is and found that almost every practical question on this board has a pharmacokinetic answer…
Can confirm. Same sequence, different timescale. The detail I would add is minor and it is already implied above.
Clinical perspective, offered as context rather than as advice.
Amycretin (AMY/GLP-1 dual agonist) emerging data relevant to the pharmacology: Phase 1 showed -13.1% body weight at only 12 weeks, the fastest trajectory ever seen for an anti-obesity agent[1].
Amylin receptor agonism enhances satiety signaling through the area postrema and reduces glucagon secretion. Combined with GLP-1R agonism, this dual mechanism may produce even greater efficacy than current agents.
Early-stage data — interpret with caution. But the trajectory is extraordinary.
[1] Novo Nordisk investor presentation, September 2023.