Octreotide for Malignant Bowel Obstruction
Octreotide should be initiated early at 150 mcg subcutaneously twice daily (or 300 mcg/day by continuous subcutaneous infusion) in patients with inoperable malignant bowel obstruction when gut function is no longer possible, to reduce gastrointestinal secretions and control nausea and vomiting. 1
Why Octreotide is Used
Octreotide is a somatostatin analogue that reduces gastrointestinal secretions in patients with malignant bowel obstruction who are not surgical candidates. 2 The NCCN guidelines specifically recommend its use when gut function is no longer considered possible, distinguishing it from situations where the goal is maintaining gut function (which would use opioids, antiemetics, and corticosteroids instead). 2
The mechanism works by decreasing intestinal secretions, which reduces the volume of fluid accumulating proximal to the obstruction, thereby controlling nausea and vomiting without requiring nasogastric tube drainage. 1
When to Use Octreotide
- Inoperable malignant bowel obstruction in patients with poor surgical candidacy (ascites, carcinomatosis, palpable intra-abdominal masses, multiple obstructions, previous abdominal radiation, advanced disease, poor performance status) 2
- When gut function is no longer possible (complete obstruction or failed attempts to maintain gut function) 2
- Early in the diagnosis due to its efficacy and tolerability 2, 1
- Patients with life expectancy of weeks to days where symptom control is the primary goal 1
How to Administer Octreotide
Initial Dosing
- Start with 150 mcg subcutaneously twice daily (total 300 mcg/day) 1
- Alternative: 300 mcg/day by continuous subcutaneous infusion 3, 4, 5, 6
- Can escalate up to 300 mcg BID if needed 1
Dose Escalation
- For severe diarrhea or refractory symptoms: 100-150 mcg subcutaneously three times daily, with escalation up to 500 mcg three times daily 2
- Intravenous option: 25-50 mcg/hour if dehydration is severe 2
Long-Acting Formulation
- If octreotide is helpful and life expectancy is at least 1 month, consider depot octreotide (LAR) 20 mg once optimal dose is established 2, 7
- This provides more convenient dosing and sustained drug exposure 7
Expected Outcomes
Symptom improvement typically occurs within 24-48 hours, with significant reductions in:
- Nausea and vomiting (improvement rates 44-93% across studies) 2, 3, 4, 5, 6
- Nasogastric tube secretions (reduction from median 890 ml to 480 ml) 3
- Ability to remove nasogastric tubes (66-100% of patients) 3, 4
- Resumption of oral intake (71% of patients) 4
The largest RCT showed significantly greater decreases in nausea, vomiting, fatigue, and anorexia compared to hyoscine (P < 0.05), though a more recent phase III trial failed to demonstrate significant effects on days free of vomiting. 2
Critical Pitfalls to Avoid
- Do NOT use metoclopramide or other prokinetic agents in complete obstruction - they worsen symptoms by increasing motility against a fixed obstruction 2, 1, 8
- Do NOT delay octreotide initiation - early use is recommended due to efficacy and tolerability 2, 1, 4
- Do NOT use octreotide when the goal is maintaining gut function - use opioids, antiemetics, and corticosteroids instead 2
Combination Therapy
Octreotide should be used alongside:
- Opioids for pain control and reducing intestinal secretions 1
- Anticholinergics (scopolamine or hyoscyamine) to decrease GI secretions and peristalsis 1
- Antiemetics (haloperidol, ondansetron, or olanzapine) for nausea control 1
- Parenteral hydration if evidence of dehydration exists 1
Safety Profile
Octreotide is well-tolerated with minimal adverse events. 3, 4, 5, 6 The most common side effects are mild nausea and agitation, with occasional transient elevation of liver enzymes that are not clinically significant. 3, 5