Prophylactic Bowel Regimen with Opioid Initiation
Start a combination of a stimulant laxative (such as senna) and a stool softener (such as docusate) immediately when initiating oxycodone, as constipation is the only opioid side effect that does not improve over time and requires prophylactic treatment. 1
Recommended Prophylactic Regimen
The National Comprehensive Cancer Network guidelines specify the following approach when starting opioids:
- Senna plus docusate: 2 tablets every morning (maximum 8-12 tablets per day) 1
- Increase the laxative dose when increasing opioid doses to maintain bowel function 1
- This prophylactic approach should be started simultaneously with opioid initiation, not after constipation develops 1
Why This Matters for Morbidity and Quality of Life
Unlike other opioid side effects (nausea, sedation, pruritus) that typically resolve within days to weeks, constipation persists throughout opioid therapy and worsens quality of life if not prevented 1. In cancer patients with metastatic disease, opioid-induced constipation can lead to:
- Severe abdominal pain and distention
- Bowel obstruction requiring hospitalization
- Premature discontinuation of adequate pain control 2
- Significantly impaired quality of life in patients already burdened by advanced cancer 3
Additional Supportive Measures
Beyond pharmacologic prophylaxis, counsel the patient on:
- Maintain adequate fluid intake 1
- Maintain adequate dietary fiber intake (though bulk-forming agents like Metamucil are unlikely to control opioid-induced constipation and are not recommended) 1
- Exercise if feasible given his spinal metastases 1
Goal of Bowel Management
The treatment goal is one non-forced bowel movement every 1-2 days 1. Monitor bowel function closely and titrate laxatives upward as needed to achieve this goal.
Common Pitfall to Avoid
Do not wait for constipation to develop before starting a bowel regimen. The evidence is clear that prophylactic treatment is essential because opioid-induced bowel dysfunction is mediated by direct effects on the enteric nervous system and does not resolve with tolerance 2. Waiting to treat constipation reactively leads to more severe symptoms, potential impaction, and inadequate pain control due to patient reluctance to take opioids 1.
If Constipation Develops Despite Prophylaxis
Should constipation occur despite the prophylactic regimen:
- First, rule out bowel obstruction (critical in patients with metastatic cancer) 1
- Check for fecal impaction 1
- Add osmotic laxatives such as polyethylene glycol, magnesium hydroxide (30-60 mL daily), or lactulose (30-60 mL daily) 1, 4
- Consider bisacodyl suppositories or enemas if oral agents fail 1
- For refractory cases in advanced illness, consider methylnaltrexone 0.15 mg/kg subcutaneously 1 or naldemedine 3