What is your strategy to prevent and treat constipation in patients initiating or receiving opioids?

I am a radiation oncologist and palliative care physician.

I  teach: "the hand that writes the opioids, writes the laxatives - or else it does the disimpaction".

Opioid induced constipation is very common, can cause physical and psychological discomfort, and have a major impact on quality of life. It sometimes is a cause for hospital admission. Patients may not address it directly due to embarrassment.

Preventing more serious constipation (and the need for more invasive secondary treatments or admissions) is worth doing and I prescribe routine prophylactic laxatives in patients starting routine opioids. 

The major tools are stimulants (sennosides) and osmotic laxatives (lactulose or PEG flakes). I usually start patients without other issues on senna 2 tabs at night, with PEG flakes 17g daily PRN. I tell them that many patients require both types of laxatives and we have a handout with instructions on how to increase the senna and PEG over time, often needed. (Many people start patients on both drugs regularly immediately). Senna can be taken 2-3 times a day. 

Lactulose can certainly be used instead of PEG however, it tends to cause a bit more cramping and has an overly sweet taste, in my clinical practice. However, it may be covered by more drug plans.

If constipation continues then try rectal suppository (e.g., bisacodyl or glycerin) and if not effective then try enema - as described by other answers here. There is also the expensive but effective naloxegel or methylnatrexone (μ-opioid receptor antagonist) for opioid induced constipation that can hopefully be used as a step before manual disimpaction.

Stool softeners like docusate are not effective according to multiple guidelines and should not be used in our population.

In terms of other supportive interventions, I do encourage hydration and physical activity as tolerated. I avoid fiber diet/fiber supplements as often our patients can't take enough fluid in to work with it and it can have the opposite effect. Prunes are fine. Focus on dignified and private time for bowels can be important in our less mobile patients.

A medication review is also often valuable. Patients are often on constipating medications including ondansetron (think about metoclopramide or domperidone for nausea instead when appropriate as these can help with bowel motility).

There are symptom management guidelines including these from my province! https://bc-cpc.ca/publications/symptom-management-guidelines/

I'm going piggyback on the "mush no push" idea.

I put all opioid naive patients on a "Musher", a stool softener and a "pusher", a bowel stimulant.

Using both tackles the two causes of opioid induced constipation: Decreased peristalsis which increases colonic transit and water extraction in the colon. So you have decreased push and trying to push hard stool.

Pericolace has a stimulant (Sena) and a water retaining agent. This is my standard baseline rec 1-2 tabs bid and I give instructions to deescalate if diarrhea emerges. Using a laxative e.g miralax or colace alone without a stool softener for prevention just doesn't add up for me when opioids are involved. 

When I encounter patients already on opioids who are already way off baseline, 5-7 days deep with clinical signs of impaction, I use lactulose. My goal at that point is to simply "empty" the colon and then put them on a mush/push regimen once they've been flushed out. 30mls q6hrs until bowel movement. Most patients never make it to the third dose. 

If lactulose doesn't work, enemas come next. 

For patients on chronic opioids with chronic constipation e.g 2 weeks between bms, I usually involve GI or palliative care with Relistor use. 

I generally tell patients that my goal is for them to have a BM as per their baseline while on opioids. For most, this is once per day, but may be once every other day, or occasionally once every 3rd day, depending on the person. Going forward, I am assuming that the patient's baseline is once per day.

This is for a patient who is opioid naive - those who have been on chronic opioids generally have some system in place already that may just require some tweaking.

I ask about the consistency of their BMs. I do not routinely recommend stool softeners unless the patient has complaints of being too hard, causing pain, or inflaming hemorrhoids. In management of constipation, I am always reminded of what a colorectal surgeon told me once during my intern year: Colace is "all mush, no push". The bowels need a gentle 'push' to keep them flowing.

I tell the patient that if they have gone 2 days without a BM, to initiate laxatives until they have a BM. My preferences are either Miralax or Dulcolax orally, as instructed on the package, initially once a day, and then up to twice a day if no BM by day 3. 

If still no BM by day 4, we discuss Dulcolax suppositories and depending on their level of discomfort, potentially an enema. If no BM by day 5, then enema is recommended. I rarely consider Mag Citrate in a patient who is on day 4-5 but staunchly refuses an enema.

Depending on how long they went without a BM after initial usage of opioids, that reflects their recommendation on how frequently to have a BM - the goal for me is one every 1-2 days. Some can just take it PRN on day 2, some require Miralax once a day, and some require it twice a day.

Every patient is certainly unique in terms of how many days they can go without a BM while being on a scale from "nothing is wrong, everything is fine" to "patient in agony due to constipation requiring disimpaction".

I have been unfortunate enough to have manually disimpacted a patient in a Radiation Oncology clinic exactly once, so I am pro-active in asking about this in most patients (especially the elderly, who have surprised me by looking like 'nothing is wrong' even at day 7 of no BMs) during consult, OTV, etc. for patients on active narcotics. I counsel similarly for Zofran.

I do not routinely use a non-pharmacological intervention for avoidance of constipation (beyond the patient remaining as active as one can tolerate), but would be interested in what others do (and whether they feel it helps).