Octreotide, lanreotide, and pasireotide are all FDA-approved synthetic peptides built on the same natural hormone, somatostatin, and they overlap significantly in what they treat. But they're not interchangeable, and the differences matter for how they're used in practice.
The Shared Mechanism
All three drugs are somatostatin analogs: synthetic peptides engineered to mimic and extend the action of somatostatin, a natural hormone that suppresses the release of growth hormone and several other hormones throughout the body. Each is used to treat acromegaly, a condition caused by excess growth hormone, and certain neuroendocrine tumors, including the diarrhea and flushing caused by carcinoid syndrome. Full individual guides to octreotide, lanreotide, and pasireotide are available elsewhere on this site.
Receptor Targeting: Where Pasireotide Differs
Octreotide and lanreotide both bind predominantly to somatostatin receptor subtype 2 (SST2). Pasireotide binds a broader set of receptors, with its highest affinity at subtype 5 (SST5), plus meaningful activity at subtypes 1, 2, and 3. This is the single biggest mechanistic difference between the group, and it's why pasireotide has a distinct approved use (Cushing's disease) that the other two don't, and why it's positioned as a second-line acromegaly option when SST2-focused drugs aren't working well enough.
Approved Uses and Overlap
Octreotide, the oldest of the three, is approved for acromegaly, carcinoid syndrome symptoms, and diarrhea associated with certain other tumors. Lanreotide is approved for acromegaly and gastroenteropancreatic neuroendocrine tumors. Pasireotide is approved for acromegaly (as Signifor LAR, specifically for patients with an inadequate response to surgery, octreotide, or lanreotide) and for Cushing's disease (as Signifor), a use the other two do not share.
Dosing and Administration
Octreotide is available in both a short-acting subcutaneous injection, dosed multiple times daily, and a long-acting depot injection (Sandostatin LAR) given once monthly. Lanreotide (Somatuline Depot) is a single long-acting formulation given as a deep subcutaneous injection once monthly. Pasireotide comes in a short-acting subcutaneous form (Signifor), typically dosed twice daily, and a long-acting intramuscular depot (Signifor LAR) given once monthly. In practice, patients on long-term treatment are usually transitioned to one of the monthly depot forms once their dose is stabilized.
Side Effect Profiles Compared
All three share a baseline side-effect profile typical of somatostatin analogs: gastrointestinal upset, injection site reactions, and an increased risk of gallstones with long-term use. Where they diverge is blood sugar: pasireotide carries a notably higher risk of hyperglycemia and new-onset diabetes than octreotide or lanreotide, to the point that glucose monitoring is a standard part of its prescribing guidance. Pasireotide also carries a specific risk of slowed heart rate and QT interval prolongation that warrants baseline cardiac monitoring. Anyone switching between these drugs, or starting one for the first time, should discuss their personal risk factors, including diabetes history and cardiac history, with their doctor.
The Bottom Line
Think of octreotide and lanreotide as close cousins with nearly the same mechanism and a similar side-effect profile, differing mainly in dosing convenience, and pasireotide as the broader-spectrum option reserved for patients who need something the other two can't provide, at the cost of a more demanding monitoring routine. None of these drugs is interchangeable without a doctor's guidance, and switching between them is a clinical decision, not a convenience choice.