Octreotide Injection: Dosage and Administration
For neuroendocrine tumors with carcinoid syndrome, initiate octreotide LAR at 20-30 mg intramuscularly every 4 weeks for chronic management, with short-acting octreotide 150-250 mcg subcutaneously three times daily for breakthrough symptoms or rapid relief. 1
FDA-Approved Indications and Standard Dosing
Carcinoid Tumors (Metastatic with Carcinoid Syndrome)
Initial therapy: Start with 100-600 mcg/day subcutaneously in 2-4 divided doses during the first 2 weeks (mean daily dosage 300 mcg). 2
Maintenance therapy: The median daily maintenance dosage is approximately 450 mcg, though clinical and biochemical benefits occur with as little as 50 mcg in some patients, while others require up to 1500 mcg/day. 2 Experience with doses above 750 mcg/day is limited. 2
Long-acting formulation (preferred for chronic management): Octreotide LAR 20-30 mg intramuscularly every 4 weeks is the standard dose, with dose and frequency increased as needed for symptom control. 1 Therapeutic levels are not achieved for 10-14 days after LAR injection. 1
Vasoactive Intestinal Peptide Tumors (VIPomas)
Initial therapy: 200-300 mcg/day subcutaneously in 2-4 divided doses during the first 2 weeks (range 150-750 mcg). 2
Maintenance therapy: Dosage may be adjusted individually to achieve therapeutic response, but doses above 450 mcg/day are usually not required. 2
Acromegaly
Initial therapy: 50 mcg subcutaneously three times daily. 2
Dose titration: Increase based on GH or IGF-1 levels, monitored every 2 weeks after initiation or dosage change. 2 The most common dosage is 100 mcg three times daily, but some patients require up to 500 mcg three times daily for maximum effectiveness. 2 Doses greater than 300 mcg/day seldom result in additional biochemical benefit. 2
Breakthrough Symptom Management
For breakthrough symptoms on LAR therapy: Add short-acting octreotide 150-250 mcg subcutaneously 3 times daily. 1 Alternatively, rescue doses of subcutaneous octreotide can be used 2-3 times per day up to a maximum daily dose of around 1 mg. 1
If breakthrough symptoms occur mainly during the week before the next LAR injection: Consider reducing administration intervals from 4 weeks to 3 weeks. 1
Emergency and Perioperative Use
Carcinoid crisis prevention: Administer short-acting octreotide by intravenous infusion, typically 50 mcg/hour, starting 12 hours before procedures, continuing during, and for 48 hours after procedures that may trigger a crisis. 3
Emergency situations (carcinoid crisis): May be given by rapid IV bolus. 2 Can also be diluted in 50-200 mL and infused intravenously over 15-30 minutes or administered by IV push over 3 minutes. 2
Administration Routes and Techniques
Subcutaneous administration: Pain may be reduced by using the smallest volume that delivers the desired dose. 2 Rotate injection sites systematically. 2
Intravenous administration: May be administered as IV push over 3 minutes, infused over 15-30 minutes, or by rapid bolus in emergencies. 2
Important incompatibility: Octreotide is not compatible in Total Parenteral Nutrition solutions due to formation of a glycosyl octreotide conjugate that may decrease efficacy. 2
Tumor Growth Control
For clinically significant tumor burden or progressive disease: Initiate octreotide or lanreotide to potentially control tumor growth if not already receiving it. 1 The PROMID study demonstrated median time to tumor progression of 14.3 months with octreotide LAR versus 6.0 months with placebo in metastatic midgut NETs. 1
Monitoring Requirements
Carcinoid tumors: Measure urinary 5-hydroxyindoleacetic acid, plasma serotonin, and plasma Substance P to monitor therapy progress. 2
VIPomas: Measure plasma vasoactive intestinal peptide (VIP) to monitor therapy progress. 2
Acromegaly: Monitor GH or IGF-1 every 2 weeks after initiating therapy or with dosage changes. 2 Goal is to achieve GH levels <5 ng/mL or IGF-1 levels within normal range. 2
Thyroid function: Assess total and/or free T4 levels at baseline and periodically during chronic therapy. 2
Cardiac monitoring: Required in patients receiving octreotide intravenously due to increased risk for higher degree atrioventricular blocks. 3
Common Pitfalls and Caveats
Insulinomas: Somatostatin analogues are often not effective in controlling hypoglycemia in patients without SSTR 2-positive insulinoma. 1 Diazoxide is the preferred treatment. 1
Gastrinomas: PPIs are the treatment of choice for gastric acid hypersecretion-associated symptoms. 1 Somatostatin analogues should only be used in refractory cases. 1
Nuclear medicine imaging: Withdraw short-acting somatostatin analogues for 24-48 hours before imaging. 1 For patients on long-acting analogues, schedule imaging toward the end of the dosing interval just before the next planned injection. 1
Common side effects: Include fat malabsorption, gallstones and gallbladder dysfunction, vitamin A and D malabsorption, headaches, diarrhea, dizziness, and hypo- and hyperglycemia. 3 Most adverse effects are mild, including injection site pain, abdominal cramps, nausea, bloating, and flatulence. 3
Above-Label Dosing in Clinical Practice
In clinical practice, approximately 30% of patients undergo at least one increase in dose or frequency above the standard label dose. 4 The most common maximum doses are 40 mg every 4 weeks, 60 mg every 4 weeks, or 30 mg every 3 weeks. 4 Of patients whose doses were increased for refractory carcinoid syndrome, 62% experienced improvement in diarrhea and 56% experienced improvement in flushing. 4