Octreotide Research & Studies

An octreotide scan, also known as somatostatin receptor scintigraphy (SRS), is valuable for detecting carcinoid tumors and various neuroendocrine tumors (NETs). Neuroendocrine cells are found in multiple areas of the body, including the brain, thyroid, lungs, and gastrointestinal tract. The scan has a sensitivity ranging from 75% to 100% for detecting pancreatic NETs. Octreotide is a synthetic analog of somatostatin, an endogenous peptide released by neuroendocrine cells, activated immune cells, and various types of inflammatory cells. Octreotide is radiolabeled with Indium-111 (111In) for imaging purposes. This radiolabeled tracer binds to tumor cells that express somatostatin receptors (SSTRs). Somatostatin is secreted in 2 forms in the body, consisting of 14 and 28 amino acids, which result from differential proteolytic processing of a single precursor. Both forms can activate SSTRs at nanomolar concentrations, as they both contain the peptide region critical for receptor interaction. Cortistatins are another class of endogenously secreted neuropeptides that bind to SSTRs with high affinity. Somatostatin exerts its antiproliferative and antisecretory effects by binding to 1 of the 5 SSTR subtypes (SSTR1, SSTR2, SSTR3, SSTR4, and SSTR5), which are G-protein–coupled receptors (GPCRs). These receptors are widely distributed in the brain, pituitary gland, pancreas, thyroid, spleen, kidneys, gastrointestinal tract, blood vessels, peripheral nervous system, and immune cells. SSTRs are most abundantly expressed in well-differentiated NETs, with SSTR2 showing the highest expression, followed by SSTR1, SSTR5, SSTR3, and SSTR4. However, expression patterns can vary by tumor type. Tumors such as pituitary adenomas, gastrointestinal tract NETs, lung NETs, pheochromocytomas, and paragangliomas typically show predominant expression of SSTR2. In contrast, adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (SSTR5), insulinomas (SSTR1 and SSTR5), and medullary thyroid carcinomas predominantly express other SSTR subtypes. Both normal and tumor cells can exhibit varying patterns of SSTR subtype expression. The 2 types of imaging are based on these receptors. The first and most common is the octreotide scan, which uses 111In-DTPA (diethylenetriamine pentaacetate)-D-Phe-1-octreotide and primarily binds to SSTR2 and SSTR5. This scan provides a planar whole-body image, which, in modern medicine, is fused with single-photon emission computed tomography (SPECT) and computed tomography (CT). The specificity of the octreotide scan and the anatomic detail from SPECT/CT are thus combined. An octreotide scan has been shown to localize 86% of carcinoids, 89% of neuroblastomas, 86% of pheochromocytomas, 94% of paragangliomas, and 80% of primitive NETs. The effectiveness of the scan in detecting medullary thyroid carcinomas and pituitary tumors is comparatively lower. The second and more recent SSTR-based imaging technique uses the positron emitter gallium (Ga) to label somatostatin analogs such as Ga-DOTATOC (DOTA-Tyr3-octreotide), Ga-DOTANOC (1-Nal3-octreotide), and Ga-DOTATATE (DOTA-(Tyr)-octreotate). Uptake of these agents is measured by positron emission tomography (PET) imaging. Gamma cameras detect the gamma emissions from the radiolabeled tracer, enabling precise localization of SSTR-positive tumor sites.

Lung injury is one of the most important diseases, which is accompanied by hypoxemia, organ failure, and a high mortality rate. There are several symptoms and causes of lung injuries. In the past years, special attention has been given to investigating the pathophysiology and the treatment of this disease. Octreotide, as an anti-inflammatory, anti-secretory, tissue-repairing, and anti-fibrotic drug, has been considered and administered for the treatment of lung injury. This review article considered the pharmacological effects of octreotide on physiopathological conditions in patients or animal models that have direct or indirect lung injury.

Pharmaceutical peptide Octreotide is a somatostatin analog with targeting and therapeutic abilities. Over the last decades, Octreotide has been developed and approved to treat acromegaly and neuroendocrine tumours, and Octreotide-based radioactive conjugates have been leveraged clinically to detect small neuroendocrine tumour sites. Meanwhile, variety of Octreotide-derived delivery strategies have been proposed and explored for tumour targeted therapeutics or diagnostics in preclinical or clinical settings. In this review, we especially focus on the preclinical development and applications of Octreotide-derived drug delivery systems, diagnostic nanosystems, therapeutic nanosystems and multifunctional nanosystems, we also briefly discuss challenges and prospects of these Octreotide-derived delivery systems.

Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.

This article reviews the current literature concerning the role of somatostatin and its synthetic analogue, octreotide, in the treatment of chylothorax.

Because of deleterious hemodynamic effects of octreotide in a nonacromegalic patient with a pancreatic fistula, we conducted a MEDLINE search of English-language journal articles to extract information on this complication of octreotide or somatostatin therapy. Few data are available regarding patients with disease states other than acromegaly. We believe octreotide should be considered when determining the cause of bradycardia.

In a limited number of case reports in infants, octreotide raised the blood glucose concentrations and decreased glucose requirements sufficiently to avoid pancreatectomy. This response occurs in the presence of frequent feedings and diazoxide therapy, and lasts from 1 month to greater than 5 years. As expected, octreotide reduces growth indices such as growth factors and growth rate in short-term assessment. However, an insufficient sample size, a lack of follow-up, and poor study design provide inconclusive data. Among the few case reports in adults with benign or malignant insulinoma, octreotide can significantly raise blood glucose concentrations. In long-term follow-up, octreotide has alleviated or reduced the frequency of hypoglycemic episodes for periods of 5 months to 2.5 years. Octreotide was administered subcutaneously in regimens of 100-1500 micrograms in three to four divided doses or as a continuous infusion. Continuous subcutaneous infusion may be attempted in patients intolerant to intermittent administration. Octreotide may worsen existing hypoglycemia as result of suppressing glucagon and growth hormone in the presence of unresponsive pancreatic hyperinsulinism. While the long-term effects of growth remain undetermined, current findings suggest octreotide may provide a reasonable addition or alternative to diazoxide in controlling symptoms of congenital hyperinsulinism. Octreotide may be useful in management of hypoglycemic symptoms in adult patients requiring medical treatment for insulinoma who are refractory or intolerant of diazoxide. Additional long-term studies are needed to address the cost effectiveness of octreotide therapy, identify patients most likely to respond, and determine the impact of octreotide on height.

Bleeding from oesophageal varices has a high death rate. Injection sclerotherapy is the most appropriate treatment but facilities for this are not always available. Balloon tamponade and vasoactive therapy may be used as stop gap measures. Somatostatin and octreotide are therapeutic candidates for the treatment of variceal bleeding and there are several trials that have compared somatostatin and octreotide with other treatments for this condition. The results of these trials are summarised and discussed. A meta analysis of the group of trials of placebo or H2 antagonists v somatostatin or octreotide showed a significant advantage of somatostatin or octreotide in terms of efficacy, but no difference in mortality. The trials discussed seem to show that somatostatin and octreotide are at least as effective as other treatments, with the benefit of fewer adverse effects, and thus represent the best vasoactive agents. Additionally, they may have a role as adjuvant treatment to emergency sclerotherapy for active bleeders and this must be further investigated.