Somatostatin Analogs
Somatostatin Analogs
Key Points
- Primary agents: Octreotide, Lanreotide
- Synthetic analogs with longer half-life than native somatostatin
- Multiple therapeutic applications in endocrine disorders
- Available in short-acting and long-acting formulations
Overview
Somatostatin analogs are synthetic peptides that mimic the actions of endogenous somatostatin with enhanced pharmacological properties. These medications are essential in managing various pediatric endocrine conditions, particularly those involving excess hormone secretion.
Mechanism of Action
Physiological Basis
- Receptor Interaction
- Binds to somatostatin receptors (primarily SSTR2 and SSTR5)
- Inhibits hormone secretion from various endocrine cells
- Reduces cell proliferation in neuroendocrine tumors
- Affects gastrointestinal motility and secretion
- Hormonal Effects
- Suppression of growth hormone secretion
- Inhibition of insulin and glucagon release
- Reduction in various gut peptide hormones
- Anti-proliferative effects on tumor cells
Pharmacological Properties
- Octreotide
- Half-life: 1.5-2 hours (immediate release)
- 28-day duration (LAR formulation)
- High affinity for SSTR2
- Lanreotide
- Extended release formulation
- 28-day duration (Autogel)
- Similar receptor profile to octreotide
Clinical Indications
Primary Indications
- Growth Hormone Excess
- Gigantism
- Early-onset acromegaly
- Post-surgical adjuvant therapy
- Congenital Hyperinsulinism
- Medical management before surgery
- Long-term treatment in diffuse disease
- Bridge therapy in diagnostic workup
- Neuroendocrine Tumors
- Functioning pancreatic NETs
- Carcinoid syndromes
- Thyrotropin-secreting adenomas
Secondary Indications
- Chronic refractory diarrhea
- Pancreatic fistulas
- Chemotherapy-induced diarrhea
- Selected cases of dumping syndrome
Administration & Dosing
Octreotide Dosing
- Short-acting Formulation
- Initial: 1-2 μg/kg/dose SC every 6-12 hours
- Maximum: 40 μg/kg/day
- Titrate based on response
- Long-acting Release (LAR)
- Starting dose: 10-20 mg every 4 weeks
- Maximum: 40 mg every 4 weeks
- Requires overlap with short-acting form
Lanreotide Dosing
- Autogel Formulation
- Initial: 60 mg every 4 weeks
- Adjust to 90 or 120 mg based on response
- Deep subcutaneous administration
Special Considerations
- Rotate injection sites
- Store and handle according to specific requirements
- Consider patient/caregiver training for home administration
- Plan for bridging therapy when switching formulations
Monitoring & Safety
Initial Assessment
- Baseline Evaluation
- Growth hormone levels/IGF-1
- Glucose homeostasis
- Thyroid function
- Liver function tests
- Gallbladder ultrasound
- ECG in selected cases
Ongoing Monitoring
- Regular Assessments
- Growth and development
- Disease-specific markers
- Blood glucose levels
- Vitamin B12 levels annually
- Quality of life measures
- Imaging Studies
- Gallbladder ultrasound every 6-12 months
- Disease-specific imaging as needed
- Tumor monitoring in NETs
Side Effects and Management
- Common Side Effects
- Injection site reactions
- Gastrointestinal symptoms
- Cholelithiasis
- Growth deceleration
- Management Strategies
- Proper injection technique
- Dietary modifications
- Prophylactic medications as needed
- Regular monitoring of growth velocity
- Vitamin supplementation when indicated
