Introduction
Somatuline Depot (lanreotide) is a synthetic somatostatin analog formulated as an extended-release injection for intramuscular administration. It is manufactured by Ipsen Pharma and was first approved by the FDA in 2007. This long-acting somatostatin analog represents an important therapeutic option for managing neuroendocrine tumors and acromegaly.
Mechanism of Action
Lanreotide binds with high affinity to somatostatin receptors (particularly subtypes 2 and 5), inhibiting the secretion of various hormones including growth hormone, insulin, glucagon, and gastroenteropancreatic hormones. In acromegaly, it reduces growth hormone and insulin-like growth factor-1 (IGF-1) levels. For neuroendocrine tumors, it inhibits tumor secretion of serotonin and other bioactive compounds while also exerting antiproliferative effects through direct action on somatostatin receptors expressed on tumor cells.
Indications
- Treatment of acromegaly in patients who have had inadequate response to surgery and/or other treatments
- Long-term treatment of carcinoid syndrome to reduce the frequency of flushing episodes and diarrhea
- Treatment of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) to improve progression-free survival
Dosage and Administration
Standard dosing:- Acromegaly: 90 mg administered every 4 weeks by deep intramuscular injection
- Neuroendocrine tumors: 120 mg administered every 4 weeks
- Administer by healthcare professional only
- Intramuscular injection in the superior outer quadrant of the buttock
- Rotate injection sites between administrations
- Allow the drug to reach room temperature before administration
- Renal impairment: No dosage adjustment needed for mild to moderate impairment; use with caution in severe renal impairment
- Hepatic impairment: No dosage adjustment recommended
- Elderly: No specific dosage adjustment required
Pharmacokinetics
Absorption: Extended-release formulation provides sustained therapeutic levels over 4 weeks. Maximum plasma concentrations reached approximately 1.2 days post-injection. Distribution: Volume of distribution is approximately 0.7 L/kg. Plasma protein binding is 78-80%, primarily to albumin and lipoproteins. Metabolism: Undergoes minimal hepatic metabolism via proteolytic enzymes. Elimination: Primarily excreted unchanged in feces (44-49%) and urine (15-20%). Terminal half-life is approximately 23-29 days.Contraindications
- Hypersensitivity to lanreotide or any component of the formulation
- History of hypersensitivity reactions to other somatostatin analogs
Warnings and Precautions
Cardiovascular: May cause bradycardia, conduction abnormalities, and arrhythmias. Monitor patients with cardiac disease. Gallbladder: May cause gallstones and biliary sludge. Perform baseline and periodic gallbladder ultrasound monitoring. Glucose metabolism: May alter blood glucose levels. Monitor blood glucose regularly in diabetic patients. Thyroid function: May cause hypothyroidism. Monitor thyroid function periodically. Vitamin levels: May reduce vitamin B12 levels. Consider monitoring in long-term therapy.Drug Interactions
Cyclosporine: May decrease cyclosporine absorption; monitor cyclosporine levels closely. Bromocriptine: May increase bromocriptine availability; monitor for increased effects. Beta-blockers: May have additive effects on heart rate; monitor for excessive bradycardia. Insulin and oral hypoglycemics: May alter glucose metabolism; adjust antidiabetic medications as needed. CYP3A4 substrates: May affect metabolism of drugs metabolized by CYP3A4; monitor accordingly.Adverse Effects
Common (≥10%):- Injection site reactions (pain, induration)
- Diarrhea
- Abdominal pain
- Nausea
- Flatulence
- Cholelithiasis
- Hyperglycemia
- Headache
- Bradycardia and conduction abnormalities
- Pancreatitis
- Hepatic dysfunction
- Severe hypoglycemia or hyperglycemia
- Intestinal obstruction
- Anaphylactic reactions
Monitoring Parameters
- Growth hormone and IGF-1 levels (acromegaly)
- Symptom control (carcinoid syndrome)
- Blood glucose levels
- Thyroid function tests
- Gallbladder ultrasound (baseline and every 6-12 months)
- Vitamin B12 levels (periodically)
- Liver function tests
- Electrocardiogram for cardiac monitoring
- Injection site evaluation
Patient Education
- This medication requires administration by a healthcare professional every 4 weeks
- Report any signs of injection site reactions
- Monitor blood sugar regularly if diabetic
- Report symptoms of gallstones (right upper quadrant pain, nausea, vomiting)
- Inform all healthcare providers about Somatuline Depot use
- Notify your doctor if you experience irregular heartbeat, dizziness, or fainting
- Maintain regular follow-up appointments for monitoring
- Discuss any new medications with your healthcare provider before starting
References
1. FDA Prescribing Information: Somatuline Depot (lanreotide) Injection 2. Melmed S, et al. A consensus statement on acromegaly therapeutic outcomes. Nature Reviews Endocrinology. 2018 3. Caplin ME, et al. Lanreotide in metastatic enteropancreatic neuroendocrine tumors. New England Journal of Medicine. 2014 4. Wolin EM, et al. Phase III study of lanreotide autogel/depot in patients with carcinoid syndrome. Journal of Clinical Oncology. 2015 5. Clinical Pharmacology [Internet]. Tampa (FL): Gold Standard, Inc.; 2023 6. Lexicomp Online [Internet]. Hudson (OH): Wolters Kluwer Clinical Drug Information, Inc.; 2023