Liraglutide

Same molecule (liraglutide), different approved dose and indication. Victoza is approved for type 2 diabetes and titrated to a maximum of 1.8mg daily. Saxenda is approved for chronic weight management and titrated higher, to 3.0mg daily. The pens and 6mg/mL concentration are identical; only the ceiling dose and label differ.

Both are GLP-1 agonists from the same Novo Nordisk lineage, but semaglutide is dosed once weekly and produces roughly double the weight loss. In the STEP 8 head-to-head, semaglutide 2.4mg weekly gave ~15.8% reduction at 68 weeks versus ~6.4% for liraglutide 3.0mg daily. Liraglutide's advantages are a longer real-world track record and once-daily flexibility rather than magnitude of effect.

Both versions start at 0.6mg daily and step up by 0.6mg each week to limit nausea. Victoza usually stops at 1.2 or 1.8mg; Saxenda continues to 2.4mg then 3.0mg. It is injected subcutaneously in the abdomen, thigh, or upper arm at roughly the same time each day, with or without food.

Mostly gastrointestinal: nausea, diarrhea, constipation, and vomiting, typically worst during dose escalation and easing over a few weeks. Liraglutide carries a boxed warning for thyroid C-cell tumors based on rodent data and is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. Use caution with pancreatitis and gallbladder disease.

Its half-life is only about 13 hours. Liraglutide binds albumin through a C16 fatty acid chain, which slows clearance enough for daily dosing but not weekly. Semaglutide's C18 diacid chain and additional structural changes push its half-life to roughly 7 days, enabling once-weekly injection.

It is an FDA-approved prescription medication (Victoza approved 2010, Saxenda 2014), not a research-grade vial. It ships as a sterile, ready-to-use prefilled pen at pharmaceutical grade, with the purity, dosing accuracy, and labeling of a finished drug product. Generic liraglutide became available in 2024.