Somatuline

Uses

Somatuline is a somatostatin analog used for the treatment of unresectable, well- or moderately-differentiated, locally advanced or metastatic gastroenteropancreatic neuroendocrine tumors and acromegaly.

Somatuline is a somatostatin analog approved for treatment of neuroendocrine tumours and acromegaly.

Somatuline is also used to associated treatment for these conditions: Acromegaly, Unresectable, locally advanced enteropancreatic neuroendocrine tumors, Unresectable, locally advanced gastroenteropancreatic neuroendocrine tumors, Unresectable, metastatic enteropancreatic neuroendocrine tumors, Unresectable, metastatic gastroenteropancreatic neuroendocrine tumors

How Somatuline works

Somatuline is a somatostatin analogue (SSA) and has mainly inhibitory effects which are mediated via somatostatin receptors (SSTRs) 2 and 5 and include inhibition of growth hormone release in the brain. Tumor SSTR activation induces downstream cell cycle arrest and/or apoptosis, and also results in blunted production of substances that support tumor growth as well as tumor angiogenesis. This leads to the anti-proliferative effects of Somatuline.

Toxicity

The most common adverse events are GI related, occurring in 67-84% of patients, and are typically mild to moderate. GI related effects are often transient, improve with subsequent injections, and most frequently include diarrhea and abdominal pain. Other GI symptoms such as nausea, vomiting, and abdominal distension are less common. It is not clear whether or not GI effects are dose related. Adverse effects relating to site of injection occur in 43% of patients and are more common in patients who self-inject as opposed to those who had health-care professionals administer the injection. A small number of patients report newly impaired glucose tolerance, fasting glucose or diabetes mellitus. Patients being treated for diabetes mellitus may experience hypoglycemia. After 1 year, up to 30% of patients may experience gallstone formation and the presence of sludge within the gallbladder due to inhibition of gallbladder and GI motility. This may be influenced by previous exposure to somatostatin analogues. Other adverse effects include reduction in left ventricular end-diastolic and end-systolic volumes, bradycardia, nasopharyngitis, and alopecia. Somatuline is classified as Pregnancy Category C.

Food Interaction

[Moderate] MONITOR: Due to their gastrointestinal pharmacologic effects, somatostatin analogs (e.g., octreotide, lanreotide) may variously affect the absorption of dietary nutrients and concomitantly administered oral medications.

Somatostatin analogs have been shown to prolong gastrointestinal transit time and inhibit intestinal absorption of some nutrients such as fat.

Clinical data are limited, however.

In case reports, octreotide has been reported to reduce the relative bioavailability of cyclosporine.

Transplant rejection and significant reductions in cyclosporine levels, sometimes to undetectable levels, have been reported in association with the interaction.

Vitamin K absorption was not affected when concomitantly administered with lanreotide according to the manufacturer.

MANAGEMENT: Clinicians should be aware of the potential for altered absorption of concomitantly administered oral medications during treatment with somatostatin analogs.

Blood levels and clinical response should be monitored, particularly for drugs that have a narrow therapeutic index, and the dosages adjusted as necessary.

Somatuline Drug Interaction

Moderate: metoprololUnknown: zolpidem, docusate, prochlorperazine, omega-3 polyunsaturated fatty acids, arginine, levocarnitine, cysteine, atorvastatin, lithium, enoxaparin, acetaminophen / hydrocodone, valproic acid, thiamine, cyanocobalamin, pyridoxine, cholecalciferol, phytonadione, menaquinone, ondansetron

Somatuline Disease Interaction

Moderate: hepatic impairment, renal impairment, thyroid abnormalities, adrenal insufficiency, bradycardia, cholelithiasis, diabetes

Volume of Distribution

Estimated Volume of Distribution = 15.1 L

Elimination Route

Somatuline forms a drug depot at the site of injection; therefore, there are 2 phases that describe the absorption of Somatuline: 1. Initial rapid subcutaneous release during the first few days of treatment where drug that has not precipitated is rapidly absorbed.
2. Slow release of drug from the depot via passive diffusion. Absorption is independent of body weight, gender, and dosage.

Half Life

Half-life is approximately 22 days

Clearance

Estimated Clearance = 23.1 L/h

Elimination Route

<5% of lanreotide is excreted in urine, and less than 0.5% is excreted unchanged in the feces suggesting biliary excretion involvement.

Innovators Monograph

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