Semaglutide — GLP-1 receptor agonist (weekly, acylated)

Semaglutide represents the most significant advance in obesity pharmacotherapy in decades. The SELECT trial's cardiovascular outcome data (2023) elevated semaglutide from a weight loss drug to a cardiovascular medicine — the 20% MACE reduction in non-diabetic obese patients is comparable to statin benefit. Key prescribing nuance: the titration protocol is critical — rushing the dose escalation dramatically increases GI intolerance and discontinuation. Muscle loss during rapid weight loss is a genuine concern — high protein intake (1.2-1.6g/kg/day) and resistance training are strongly recommended adjuncts. The 'Ozempic face' (facial volume loss) is a cosmetic concern from rapid weight loss, not a direct drug effect. Supply shortages have led to widespread compounding pharmacy use — compounded semaglutide safety/potency is unregulated.

Overview

This page is part of Hormonaly's evidence-graded compound library. All clinical claims are linked to peer-reviewed sources via our dual-layer citation verification pipeline.

Compound Class

GLP-1 receptor agonist (weekly, acylated)

Mechanism of Action

Human GLP-1 analog with 94% amino acid sequence homology to native GLP-1. Modified at position 8 (Aib substitution — DPP-4 resistance) and lysine 26 (C18 fatty diacid chain via linker — albumin binding enabling once-weekly dosing; t½ ~7 days). Mechanism: (1) GLP-1R agonism in pancreatic β-cells → glucose-dependent insulin secretion; (2) Suppresses glucagon (α-cells); (3) Hypothalamic GLP-1R activation → satiety, reduced appetite, decreased caloric intake; (4) Delays gastric emptying; (5) Direct cardiovascular effects via GLP-1R in cardiac tissue — reduces inflammation, improves endothelial function. The SUSTAIN-6 and SELECT trials demonstrated CV mortality reduction. STEP trials: Wegovy (2.4mg weekly) achieves 15-17% mean body weight loss at 68 weeks vs ~2.4% placebo.

Regulatory Status

FDA approved — Ozempic (SC, T2DM) 2017; Rybelsus (oral, T2DM) 2019; Wegovy (SC 2.4mg, obesity) 2021; semaglutide CVI (Ozempic, CV risk reduction) 2023

Evidence Level

High — Multiple FDA-approved indications with Phase 3 SUSTAIN (T2DM), STEP (obesity), and SELECT (CV outcomes) trial programs. SELECT (2023, n=17,604) showed 20% reduction in major adverse cardiovascular events in obese/overweight adults without diabetes — first weight loss drug with proven CV mortality benefit.