What it is
Octreotide is an eight-amino-acid peptide drug that copies somatostatin, the body's general-purpose "off switch" for hormones. Its structure is compact and deliberate:
- Eight amino acids closed into a ring by a disulfide bond between the cysteines at positions 2 and 7;
- Two mirror-image amino acids — D-phenylalanine at the start and D-tryptophan at position 4;
- A threoninol at the end instead of an ordinary amino acid.
The label chemical name spells that out; the free peptide weighs 1,019.3.
How it works
Octreotide acts on somatostatin receptors. The Sandostatin label calls it an even more potent inhibitor of growth hormone, glucagon and insulin than somatostatin itself, and lists a long run of other hormones it suppresses: serotonin, gastrin, vasoactive intestinal peptide (VIP), secretin, motilin and pancreatic polypeptide. It also blunts the pituitary's response to gonadotropin-releasing hormone and reduces blood flow to the gut.
That breadth is why one peptide treats diseases that look unrelated: they are all conditions in which a hormone is being over-produced.
What it is approved for
| Condition | What octreotide does, per the label |
|---|---|
| Acromegaly | Lowers growth hormone and IGF-1 when surgery, pituitary radiation and bromocriptine have been inadequate or are not possible |
| Metastatic carcinoid tumours | Suppresses the severe diarrhoea and flushing their hormones cause |
| VIPomas | Treats the profuse watery diarrhoea caused by VIP-secreting tumours |
The label carries an unusually plain limitation of use: trials did not show improvement in tumour size or growth rate, and "were not optimally designed to detect such effects." What octreotide is approved to control is the hormone and the symptom, not the tumour.
Four forms of one molecule
| Product | Route | First approved (Drugs@FDA) |
|---|---|---|
| Sandostatin | Injection under the skin or into a vein | 1988 |
| Sandostatin LAR Depot | Long-acting depot injection | 1998 |
| Mycapssa | Oral delayed-release capsule, 20 mg | 2020 |
| Bynfezia Pen | Pre-filled pen for injection | 2024 |
After an injection under the skin, octreotide is absorbed "rapidly and completely," reaching peak levels within about half an hour.
What swallowing it costs
Mycapssa is one of the few peptide drugs sold as a capsule, and its label puts a number on the price of the gut. A single 20 mg capsule gave about the same total exposure as a 0.1 mg injection under the skin — the capsule has to carry 200 times the mass to deliver the same amount to the blood — and its peak level was 33% lower and arrived later (about 1.7–2.5 hours instead of 0.5).
It is approved only for maintenance: in acromegaly patients who have already responded to and tolerated octreotide or lanreotide injections. The approving trial enrolled 56 patients for nine months against placebo (NCT03252353). For the other oral exception in this library, compare the vasopressin analogue desmopressin, whose tablet reaches the blood at about 0.16% of an intravenous dose.
Safety
The Sandostatin label's warnings are what a general hormone suppressor would predict: heart-rhythm effects (slow heart rate, conduction abnormalities, and an increased risk of higher-degree heart block when given intravenously), gallstones and their complications, high or low blood sugar — because it suppresses both insulin and glucagon — thyroid changes, and fatty stools from reduced fat absorption.
Where it stands
FDA application data list 17 octreotide applications on 2026-09-24: four brand products and 13 generics, the first approved in 2005. PubMed indexes 12,759 records, 541 tagged as randomised controlled trials.
Related reading
Octreotide works against the hormone that IGF-1 LR3 imitates: it lowers IGF-1 in acromegaly. VIP is one of the gut hormones it suppresses, and VIPomas are one of its three labelled uses. Growth-hormone releasers such as tesamorelin push in the opposite direction.